Non-Idiopathic Spine Deformities in Young Children

Non-Idiopathic Spine Deformities in Young Children

 

Muharrem Yazici Editor

Non-Idiopathic Spine Deformities in Young Children

Editor Muharrem Yazici, MD Department of Orthopedics Hacettepe University   Faculty of Medicine  Sihhiye, Ankara 06100 Turkey [email protected]

ISBN  978-3-642-19416-0     e-ISBN  978-3-642-19417-7 DOI  10.1007/978-3-642-19417-7 Springer Heidelberg Dordrecht London New York Library of Congress Control Number: 2011929934 © EFORT 2011 This work is subject to copyright. All rights are reserved, whether the whole or part of the ­m aterial is ­concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilm or in any other way, and storage in data banks. Duplication of this publication or parts thereof is permitted only under the provisions of the German Copyright Law of September 9, 1965, in its current version, and permission for use must always be obtained from Springer. Violations are liable to prosecution under the German Copyright Law. The use of general descriptive names, registered names, trademarks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant ­protective laws and regulations and therefore free for general use. Product liability: The publishers cannot guarantee the accuracy of any information about dosage and application contained in this book. In every individual case the user must check such information by consulting the relevant literature. Cover design: eStudioCalamar, Figueres/Berlin Printed on acid-free paper Springer is part of Springer Science+Business Media (www.springer.com)

To my mentors, Marc A. Asher, Yucel Tumer, Adil Surat and A. Mumtaz Alpaslan For teaching me that the process of learning is endless…

 

Preface

The term axis defines a straight line interconnecting the two poles of a spherical object. In biology, it denotes the imaginary central line of the body, or more specifically the vertebral column. The bones of the skull and the vertebral column together make up the portion of the skeletal system that is known as the axial skeleton. The vertebral column does not just geographically reside in the center of the body; it occupies such a position physiologically and functionally as well. Just as it is impossible for an object with a deviated axis to fulfill its predetermined function or structure, any deviation of the vertebral column from the normal will invariably affect the appearance and function of the whole body. An anomaly such as this appearing during the period of growth does not just exist in a limited period of time and constitute problems with a static nature, but changes with the passage of time and becomes a dynamic pathology. Spinal disorders in small children have become one of the most heatedly discussed subjects of spinal surgery in the past few years. Impressive progress in corrective deformity surgery has paved the way for procedures usually reserved for adults and adolescents to be modified to be used for the treatment of spinal deformities in much younger children. However, the ability of perfectly correcting deformities in all three planes in skeletally mature patients has only solved part of the problem. It has also given rise to additional concerns, especially those regarding the loss of motion in the vertebral column. Minor or major loss of function in the short term and adjacent segment disease in the long term are inevitable results of these procedures. Yet, when the cosmetic and functional problems caused by the deformity at that moment and the potential complications associated with fusion in an undeterminable time in the future are weighed, usually the latter problem is preferred as applied in advanced deformities and corrective surgery. In younger children, however, a much graver problem arises that dwarfs in the aforementioned ones in scope: the loss of the growth potential of the spinal column. The inability of the axial skeleton to grow does not just mean the inability of the axis to grow. It affects the growth potential of the whole body. A spine not permitted to grow will result in a short trunk and an ­underdeveloped thorax. The complications that follow a thorax unable to develop are so huge as to not even be compared with those caused by a vertebral column that is short, immobile or a candidate for adjacent segment degeneration. Thoracic insufficiency is a life-threatening, or in the very least, profoundly quality-of-life altering complication. The last decade of pediatric spinal surgery has been about trying to understand the causes and results of early onset scoliosis, identify coexisting problems, foreseeing new ones and solving them all. I sincerely hope that this book will be a contribution to this vii

viii

Preface

struggle, however small it may be. The information contained in this book is derived from the valuable experiences of those spinal surgeons that are involved with the management of young children with spinal deformities in their day-to-day practice, and will, hopefully, assist the practice of every other surgeon interested in this subject while stimulating up and coming research into the field. An important portion of the content of this book was covered during the pre-meeting course of the 28th EPOS Meeting in 2009 in Lisbon. Although they did not participate as speakers in this course at that time, Carol Hasler, Ilkka Helenius, Dror Ovadia and Thanos Tsirikos have kindly agreed to share their knowledge and experience for the creation of this book. Also, without the belief in and support of EFORT Secretary General and Lisbon EPOS Meeting host Manuel Cassiano Neves, the publication of this book would not be possible. We are able to have a book such as this because EFORT, one of the leading teaching organizations in orthopaedic surgery in the world, believed in the significance of this undertaking and never withheld its generous support. I am proud to have been chosen to lead this project and would, once more, like to thank everybody involved for their contributions.  Ankara, Turkey Muharrem Yazici

Contents

Part I  Growth   1  Normal and Abnormal Growth of Spine......................................................... Ilkka J. Helenius

3

Part II  Evaluation   2  Clinical Evaluation............................................................................................ Dror Ovadia

17

  3  Radiologic Evaluation of Non-Idiopathic Early Onset Spine Deformities.......... Jorge Mineiro

25

Part III  Deformities   4  Congenital Deformities of the Spine................................................................. Athanasios I. Tsirikos

45

  5  Neuromuscular Spine Deformities................................................................... Carol-Claudius Hasler

73

  6  Cerebral Palsy.................................................................................................... Freeman Miller

77

  7  Duchenne’s Muscular Dystrophy and Spinal Muscular Atrophy................. Dietrich Schlenzka

87

  8  Other Neuromuscular Disorders with Scoliosis.............................................. Carol-Claudius Hasler

97

Part IV  Management   9  Delaying Tactics: Traction, Casting, and Bracing.......................................... 109 Charles E. Johnston II ix

x

Contents

10  Indications for Non-fusion Operative   Techniques in Non-Idiopathic Scoliosis........................................................... 121 Charles E. Johnston II 11  Growth Modulation Techniques for Non-Idiopathic   Early Onset Scoliosis......................................................................................... 133 Eric J. Wall and Donita I. Bylski-Austrow 12  Instrumentation in the Childhood Spinal Deformities:   Challenges, Problems, Limitations, and Solutions.......................................... 145 Muharrem Yazici and Z. Deniz Olgun 13  Fusionless Instrumentation for Non-Idiopathic Spine Deformities   of Young Children: The Growing Rod Technique.......................................... 157 Muharrem Yazici and Z. Deniz Olgun 14  VEPTR Instrumentation in Early Onset Scoliosis.......................................... 167 Fritz Hefti, Arne Mehrkens, and Carol-Claudius Hasler Index............................................................................................................................ 173

Part I Growth

 

Normal and Abnormal Growth of Spine

1

Ilkka J. Helenius

1.1  Introduction Height will increase by 350% and weight 20-fold from birth to adulthood (Dimeglio and Bonnel 1990; Dimeglio 1992, 2006). The spine, femur, and tibia will triple in length. In addition to two-dimensional growth, also volumetric growth occurs: at birth the volume of thorax is 6.7% of the final volume and the volume of lumbar vertebrae will be multiplied by six from the age of 5 years to skeletal maturity. The growth of spine, thoracic cage, and lungs are closely associated with each other (Dimeglio and Bonnel 1990; Dimeglio 1992, 2006). Disturbance within spinal or thoracic cage growth will adversely affect growth of lungs. Disturbance of growth may be due to dietary conditions (lack of energy, vitamin D, calcium, etc), skeletal dysplasia, spinal deformity, spinal fusion at an early age, and localized factors (after skeletal infections, trauma, etc.). In this chapter, focus will be on normal growth of spine, but also some disturbances of growth will be reviewed.

1.2  Spinal Ossification and Remodeling During Growth Most vertebrae have at least three growth zones, and therefore the end morphology will be the result of 100 growth plates (Dimeglio and Bonnel 1990; Dimeglio 1992, 2006). The pattern of posterior arch growth is linked to the presence of neural stem and differs from vertebral body growth, which more or less resembles growth of long bones. Ossification of

I.J. Helenius Turku Children’s Hospital, Turku University Central Hospital, Kiinamyllynkatu 4-8, Turku FIN-20521, Finland e-mail: [email protected] M. Yazici (ed.), Non-Idiopathic Spine Deformities in Young Children, DOI: 10.1007/978-3-642-19417-7_1, © 2011 EFORT

3

4

1



I.J. Helenius

the vertebral bodies starts at the third month of intrauterine life. Three primary ossification centers are present within each vertebra, except for C1, C2, and sacrum. Ossification first appears in the lower thoracic and upper lumbar spine and radiates from there to both cranial and caudal direction (Ganey and Ogden 2001). Within the cervical spine, the primary ossification centers of the vertebral bodies appear sequentially after the primary centers appear in the vertebral arches. Vertebral body ossification begins in the lower cervical spine (C6 and 7). Posterior osseous defects, in which the ossification centers of the neural arch fail to fuse, are quite common: incidence of spina bifida occulta is estimated to be as high as 20%. The role of posterior element deficits in the development of conditions like spondylolisthesis is controversial. The atlas (C1) centrum has one primary center of ossification, and each of the two neural arches has their own (Ganey and Ogden 2001). The two posterior centers are present prenatally, while the anterior center may not appear until several months postnatally, which is good to know when evaluating this area in newborn and infants. The axis (C2) develops five primary and two secondary centers of ossification. The centrum and neural arches form in the conventional manner, and the odontoid process forms two laterally situated centers, which fuse almost always in the perinatal period. At birth, lumbar vertebrae are relatively smaller than cervical and thoracic vertebrae (Dimeglio and Bonnel 1990; Dimeglio 1992). During growth, lumbar vertebrae and discs increase in size about 2 mm per year, while in the thoracic spine, the average increase is only 1 mm per year. The discs account for approximately 35% of the height of the spinal segment at birth, while at maturity this proportion is 22% in the cervical spine, 18% in the thoracic spine, and 35% of the lumbar spine (Dimeglio and Bonnel 1990; Dimeglio 1992). The anterior and posterior portions of the vertebrae do not grow in a similar fashion: in the thoracic spine, the posterior components grow at a faster manner than the anterior part, which results in the development of thoracic kyphosis. The reverse occurs in the lumbar spine. The anatomic shape of the vertebral bodies change during growth: the facet joint orientation is more horizontal in early childhood, increasing the risk of fracture dislocation of the spine in younger patients (Puisto et al. 2010).

1.3  Height, Sitting Height, and Length of Spine Skeleton has two rapid growth periods from birth to 5  years and during puberty (Dimeglio and Bonnel 1990; Dimeglio 1992, 2006). At birth, the standing height of the neonate is about 30% of final height. The spine makes up to 60% of the sitting height, whereas the head represents 20% and pelvis the remaining 20%. At birth, the sitting height averages 34 cm, at 5 years 62 cm, while at maturity 88 cm for women and 92 cm for men (Dimeglio 1992). The length of spine will nearly triple between birth and adulthood. At birth, the vertebral column (C1-Sacrum) is approximately 24  cm long. At maturity the average adult spine is approximately 70  cm long in men and 65  cm in women. The cervical spine length averages 12 cm, ­thoracic spine 28 cm, lumbar spine 18 cm, and sacrum 12 cm.

5

1  Normal and Abnormal Growth of Spine

1.4  Cervical Spine Growth At birth, the cervical spine measures 3.7 cm, growing about 9 cm to reach the adult length of 12–13 cm (Dimeglio 2006). The length of the cervical spine will double by the age of 6. The cervical spine represents 22% of the C1–S1 segment and about 15% of the sitting height. The diameter of spinal canal typically decreases from C1 to C7. In the adult, the normal transverse diameter of C3 is 27 mm and the average sagittal diameter is 19 mm.

1.5  T1–S1 Growth The T1–S1 segment measures about 19 cm at birth, 28 cm at the age of 5, and 45 cm at skeletal maturity (Fig. 1.1). This segment represents 49% of the sitting height and 64% of the length of spine. During the first 5 years of life, its rate of growth is >2 cm per year, 0.9 cm between the ages of 5 and 10 years, and 1.8 cm during puberty (Dimeglio 1992). Thoracic spine (T1–T12) is about 11 cm long at birth, 18 cm at 5 years of age, and will

Males

T1

Adult

Females

10 years Boys Girls T1

Boys Newborn Boys Girls

28 cm

5 years Girls

T1

22 cm

22 cm

T1

T12

18 cm 11 cm

L5 Sacrum

18 cm

T12 L1

7.5 cm

L1 T12 L1

11 cm

T12 L1

7.5 cm

26.5 cm

10.5 cm

12.5 cm

16 cm

15.5 cm

12.5 cm

10.5 cm

L5 L5

L5 Sacrum

Sacrum

Sacrum

Fig. 1.1  Growth of the T1–L5 segment of spine (Dimeglio and Bonnel 1990; Dimeglio 1992)

6



I.J. Helenius

1

Newborn

5 years

10 years

15 years

Fig. 1.2  Growth of spinal canal. At the age of 5 years, spinal canal has achieved 95% of its adult size (Dimeglio and Bonnel 1990; Dimeglio 1992, 2006)

reach a length of 28 cm in boys and 26 cm in girls at maturity. The thoracic segment has a rapid growth period from birth to 5 years of age (7 cm), a slower phase from 5 to 10 (4 cm), and a rapid growth through puberty (7  cm). The thoracic spinal canal is narrower than cervical or lumbar, thus producing risk for spinal cord in the case of traumatic injury or a process occupying space at this level. At the end of 5 years, the spinal canal growth to 95% of its definitive size (Fig. 1.2). The average transverse and sagittal diameters at T7 is about 15 mm. The L1–L5 segment is about 7 cm at birth and will increase to about 16 cm in men and 15.5  cm in women (Dimeglio 1992). In a similar fashion to thoracic spine, the growth velocity varies with age, being 3 cm from 0 to 5 years, 2 cm from 5 to 10 years, and more rapid through puberty (gain about 3 cm from 10 to 18). At birth, the spinal cord ends at L3, and at maturity it ends between L1 and L2. The sagittal curves develop under the influence of neurologic maturation (Dimeglio 1992). The cervical lordosis appears when the child can hold his head straight (3 months). Thoracic kyphosis appears when the child can keep his trunk upright (6 months), and lumbar lordosis appears when he can stand, at the age of 14–16 months.

1.6  Thoracic Cage Growth Dimeglio has termed the growth of the thorax or thoracic growth “the fourth dimension” of growth of spine (Dimeglio and Bonnel 1990; Dimeglio 1992, 2006). From birth to age of 5, thoracic volume increases fivefold (Dimeglio 1992) (Fig. 1.3). On the other hand, by the age of 5 years, almost 60% of the sitting height is achieved, while only about 30% of thoracic volume has been achieved (Fig.  1.4). At the end of growth, the thorax has an anteroposterior diameter of about 21 cm in boys and 17 cm in girls, representing a growth of 9 cm since birth. The transverse diameter is 28 cm in boys and 24 cm in girls at the end of growth, meaning an increase of 14 cm since birth. The thoracic volume makes up to 6% at birth, 30% at the age of 5 years, and 50% at 10 years (Fig. 1.3). In experimental models, rib elongation experiments produced scoliosis by ­pushing spine toward normal side (Sevastik et al. 1990). Rib resection (shortening) will produce

7

1  Normal and Abnormal Growth of Spine 100% 50% 30% 6%

Newborn

5 years

10 years

15 years

Fig. 1.3  Volumetric growth of thoracic cage (Dimeglio and Bonnel 1990; Dimeglio 1992, 2006) T1

69%

T12 L1

31%

L5 Sacrum

26% Weight

Thoracic volume

T1-S1 height

Fig. 1.4  Comparison of weight, thoracic cage volume, and T1–S1 length at the age of 5  years. Almost 70% of spinal height has been achieved, in contrast to 30% of thoracic volume at this age (Dimeglio 1992)

scoliosis toward resection side (Langenskiöld and Michelsson 1961). This resulting scoliosis can be partly corrected by elongation of convex ribs. Thus, the integrity of thoracic cage seems to be needed for normal spinal growth based on experimental data. Thoracotomy in early childhood may result in rib fusions and pleural scarring (Gilsanz et al. 1983). Sistonen et al. (2009) evaluated 100 patients operated for esophageal atresia

8

1



I.J. Helenius

during neonatal period. Of these 18% had developed scoliosis and rib fusions when ­followed up to adulthood. Congenital scoliosis associated with rib fusions may cause restrictive lung disease by producing segmental hypoplasia of the hemithorax (Campbell et al. 2003). An extreme form of spinal and thoracic cage growth disturbance is spondylothoracic dysplasia (Ramirez et al. 2007). Extreme extrinsic restrictive lung disease will develop as a result of posterior rib fusion and severe shortening of the thoracic spine due to block vertebrae. Ramirez et al. (2007) evaluated the natural history of 19 patients prospectively from neonatal care and nine retrospectively. Mortality in early neonatal period was high (42%, 8/19). In the remaining patients, the average thoracic spinal segment was 5.1 cm, representing 24% of normal values. The average height of the patients was 1.15 m representing the 1.15 percentile. The average anteroposterior diameter of the chest was significantly reduced and the vital capacity was 28% of the predicted values estimated using arm span.

1.7  Lung Growth Growth of lung occurs by volume expansion and tissue hypertophy (Sponseller et al. 2007; Davies and Reid 1970; Thurlbeck 1982). From birth to maturity, the functional residual capacity increases from 80 to 3,000 mL, and the lung weight increases from 60 to 750 g. Up to 85% of alveoli develop after birth (Davies and Reid 1970). Alveoli are added by multi­ plication after birth until the age of 8 years, although the most rapid phase occurs from birth until the age of 3 years (Davies and Reid 1970; Thurlbeck 1982). In later childhood, lung volumes increase mostly by an increase in the size of alveoli. In normal children, the ratio of residual volume per total lung capacity increases with age due to increased stiffness of chest wall that is greater than respiratory muscle strength increment that occurs with age. Severe scoliosis in early childhood increases mortality in early adulthood (Pehrsson et al. 1992; Boffa et al. 1984). In an autopsy study, Davies and Reid (1971) were able to demonstrate hypoplasia of the lung with decreased number of alveoli in early onset scoliosis resulting to death. Lung volumes and pulmonary arteries were smaller and the latter also decreased in number. In addition, alveoli were reduced more in number than expected, suggesting a compensatory increase in size of each alveolus. In a long-term follow-up study, Pehrsson et al. (1991) were able to show that scoliosis patients with vital capacity below 45% of predicted or scoliosis of 110° are at a significant risk for respiratory failure.

1.8  Growth of Fused Spine with or without Instrumentation Experimental high thoracic spinal fusion in young rabbits produces hypoplasia of the entire upper thorax including ribs, sternum, and lung volume (Canavese et al. 2007). In addition, asymmetric high thoracic tether at Th1-3 produced larger scoliosis than midthoracic tether in growing rabbits (Carpintero et al. 1997).

1  Normal and Abnormal Growth of Spine

9

The loss of growth after circumferential spinal growth can be estimated using the formula by Winter (1977): 0.07 × number of fused vertebrae × years of growth remaining. Using this formula it can be estimated that on a 5-year-old girl, circumferential spinal fusion from T7 to T12 results in 4.2 cm loss of spinal growth (0.07 × 6 vertebrae × 10 years growth). Dimeglio (1992, 2006) has proposed a more detailed formula based on sitting height and bone age. Using similar case as above (assuming that skeletal age is in this setting similar to bone age), the loss of growth can be calculated as follows: The remaining sitting height is about 26 cm for a 5-year-old girl. The thoracic spine makes up to 30% of the sitting height. The remaining growth of the thoracic spine is therefore at the age of 5 years: 26 cm × 30/100 = 7.8 cm. The deficit of growth/sitting height due to six vertebral arthrodesis is 6/12 × 7.8 cm = 3.9 cm. Immature vertebral bodies continue to grow after solid posterior spinal fusion (Hallock et  al. 1957), which was later named as the Crankshaft phenomenon by Dubousset et al. (1989). Crankshaft has been defined as a curve progression of >10° following posterior fusion. Bending of the posterior fusion mass is thought to occur because of growth potential in the vertebral bodies of the fused segment. In the differential diagnosis, adding on (curve progression above or below operated area) and pseudoarthrosis should be excluded. The ability of an anterior and posterior fusion to stop the spinal growth and crankshaft phenomenon is an accepted principle (Shufflebarger and Clark 1991) but remains to be proven by prospective high-level follow-up study (Sponseller et al. 2007). In patients with infantile or juvenile idiopathic scoliosis, studies support the hypothesis that curve progression after posterior spinal fusion is proportional to the number of unfused growth centers and number of years of growth remaining (Sponseller et al. 2007; Dubousset et al. 1989). Growth areas of the spine in congenital scoliosis patients have varied growth potential as many vertebrae are malformed with failures of formation and segmentation. Therefore, the risk of crankshaft has been expected to be lower in congenital scoliosis patients. Hefti and McMaster (1983) followed 24 infantile and juvenile idiopathic scoliosis patients for a mean of 4.5 years. They were operated using the Harrington instrumentation and posterior spinal fusion at the age of 10 years, ranging from 8.5 to 11 years. The length of spine remained almost the same with only 0.4 cm growth. The height of the vertebral bodies in the fusion area increased by 0.067 cm, while the intervertebral disc spaces narrowed initially thus accommodating this growth. At the end of follow-up, the vertebral bodies bulged laterally toward the convexity and pivoted on the posterior fusion, giving rise to loss of correction (9°), increasing vertebral rotation and recurrence of the rib hump. Winter and Moe (1982) evaluated 32 congenital scoliosis patients operated before the age of 5 using posterior spinal fusion with abundant bone graft material with a mean follow-up of 9.5 years. Nine patients were followed up to maturity. A bending of solid spinal fusion ³10° occurred in 6 (19%) of all patients. Of the nine patients followed up to skeletal maturity, the sitting height was less than third percentile of normal population in six patients. One of these nine patients developed lordosis of the whole spine (kyphosis of −73°). On the other hand, in patients with congenital kyphosis, posterior arthrodesis alone was highly effective and gave better correction of kyphosis than combined anteroposterior approach (16° vs. 4°).

10

1



I.J. Helenius

Winter et al. (1984) also evaluated outcomes of posterior spinal fusion in 290 congenital scoliosis patients aged 5 or more at the time of surgery. Roughly half of the patients were operated without and half with Harrington instrumentation. Bending of solid spinal fusion ³10° occurred in 19% of these patients during follow-up. High thoracic spinal fusions above sixth thoracic vertebrae resulted in short thoracic spine and worse pulmonary function tests than mid-thoracic spinal fusions (Karol et al. 2008). A critical length of thoracic spine needed for sufficient lung volume development appeared to be 18 cm. Pedicle screws in young children cross the neurocentral synchondrosis. In experimental models, asymmetric neurocentral synchondrosis closure will result in short and small pedicle on the concavity of scoliosis (Zhang and Sucato 2008). Recently, Ruf et  al. (2009) reviewed 30 children operated for congenital scoliosis caused by a fully segmented hemivertebra using posterolateral technique and bilateral pedicle screws at the age of 1 and 2 years. Follow-up time was more than 5 years in 14 children and more than 10 years in 5 children. None of these children showed evidence of neurologic compromise and MRI and CT scans showed no evidence of spinal stenosis. Despite transpedicular fixation, the vertebral bodies demonstrated growth in longitudinal as well as vertical direction. However, the posterior instrumentation acted like tether leading to less kyphosis or increasing lordosis (Ruf et al. 2009). Three cases with multisegmental instrumentation developed thoracic hypokyphosis with growth. After rod removal, the thoracic spine regained kyphosis.

1.9  Fusionless Instrumentation Dual growing rod constructs represent the current golden standard surgical treatment option for progressive early onset scoliosis patients, in whom a long section of the spine is involved in the deformity or if fusion of a long section is required to achieve curve control (Yazici and Emans 2009). In a multicenter study, Akbarnia et  al. (2005) evaluated 23 patients (7 idiopathic, 3 congenital, 13 secondary) with a minimum 2-year follow-up. All patients underwent lengthening of the implants every 6 months. The average number of lengthening was 6.6 and this resulted in growth of 4.6 cm or 1.2 cm/year. Patients with congenital scoliosis received significantly less length during initial procedure while lengthening produced similar growth. Distraction of the spine with growing rods may stimulate growth of spine, since growth of 1.2 cm per year exceeds that of normal spine. Recently, growing spine study group (Sankar et al. 2009) evaluated the received T1–S1 gain over following surgical lengthening. A decrease of T1–S1 gain from 10 mm at first lengthening to 6 mm at seventh lengthening occurred, but still some gain occurred even after multiple lengthening. VEPTR implant has been designed primarily for the treatment of congenital scoliosis associated with fused ribs (Campbell et al. 2004a). Campbell et al. (2004b) evaluated the outcomes of 27 patients with congenital scoliosis associated with fused ribs, who underwent an opening wedge thoracostomy and VEPTR ­implantation at the age of 3.2 years with a mean 5.7-year follow-up. Twenty-five patients had at least one hemivertebra on the convexity and a unilateral bar on the concavity (mean length 4.2 vertebrae). The mean

1  Normal and Abnormal Growth of Spine

11

length of thoracic spine was 11.7  cm preoperatively, 12.3  cm immediately after index procedure, and 15.7 cm at final follow-up, representing an increase of thoracic height a mean of 0.7 cm per year (range 0.2–1.37 cm per year). These findings of continued thoracic spinal growth have been confirmed by Emans et al. (2005). On the other hand, ribbased instrumentation may increase the compliance of rib cage, thus decreasing functional lung volumes while increasing residual volume (Mayer and Redding 2009). The most recent tool for correcting early onset scoliosis is the Shilla technique (Lenke and Dobbs 2007; McCarthy et al. 2008). It is a pedicle screw construct, with fixed apical pedicle screws and sliding pedicle screws on top and bottom of the construct with extralong rods allowing growth along them. Recently, McCarthy (2008) has reported that trunk length has increased by 12% during 2-year follow-up in patients operated using the Shilla technique, but this growth includes also the immediate trunk lengthening due to scoliosis correction. Longer follow-up is needed to see whether local apical bony fusion or at the top or bottom fusion areas will diminish the remaining growth of spine. This kind of construct might be most suitable for syndromic early onset scoliosis patients, in whom repeated surgical procedures for lengthening purpose are a clear risk.

1.10  Conclusions Spinal and thoracic cage growth is critical for lung growth and function as well as reasonable life. Spinal length will almost triple from birth to maturity. About 60% of the sitting height has been achieved by the age of 5 years, while only 30% of thoracic volume exists at this time (Fig. 1.4). The critical length of thoracic spine needed for satisfactory pulmonary function appears to be about 18 cm, which is the length of normal thoracic spine at the age of 5 years. The estimated loss of growth due to circumferential spinal fusion can be calculated by Dimeglio’s formula (Dimeglio 1992, 2006) including sitting height, skeletal age, and number of fused vertebral bodies.

References Akbarnia, B.A., Marks, D.S., Boachie-Adjei, O., et al.: Dual growing rod technique for the treatment of progressive early-onset scoliosis. A multicenter study. Spine 30, S46–S57 (2005) Boffa, P., Stovin, P., Shneerson, J.: Lung developmental abnormalities in severe scoliosis. Thorax 39, 681–682 (1984) Campbell, R.M., Fallon, M.C., Moore, D.P., et al.: The characteristics of thoracic insufficiency syndrome associated with fused ribs and congenital scoliosis. J. Bone Joint Surg. Am. 85-A, 399–408 (2003) Campbell Jr., R.M., Smith, M.D., Hell-Vocke, A.K.: Expansion thoracoplasty: the surgical technique of opening wedge thoracostomy. J. Bone Joint Surg. Am. 86-A(Suppl 1), 51–64 (2004a) Campbell Jr., R.M., Smith, M.D., Mayes, T.C., et al.: The effect of opening wedge thoracostomy on thoracic insufficiency syndrome associated with fuse ribs and congenital scoliosis. J. Bone Joint Surg. Am. 86-A, 1659–1674 (2004b) Canavese, F., Dimeglio, A., Volpatti, D., et al.: Dorsal arthrodesis of thoracic spine and effects on thorax growth in prepubertal New Zealand white rabbits. Spine 32, E443–E450 (2007)

12

1



I.J. Helenius

Carpintero, P., Mesa, M., Garcia, J., Carpintero, A.: Scoliosis induced by asymmetric lordosis and rotation: an experimental study. Spine 22, 2202–2206 (1997) Davies, G., Reid, L.: Growth of the alveoli and pulmonary arteries in childhood. Thorax 25, 669–681 (1970) Davies, G., Reid, L.: Effect of scoliosis on growth of alveoli and pulmonary arteries and on right ventricle. Arch. Dis. Child. 46, 623–632 (1971) Dimeglio, A.: Growth of the spine before the age 5 years. J. Pediatr. Orthop. B 1, 102–107 (1992) Dimeglio, A.: Growth in pediatric orthopedics. In: Morrissy, R.T., Weinstein, S.L. (eds.) Lovell and Winter’s Pediatric Orthopaedics, 6th edn, pp. 35–65. Lippincott Williams & Wilkins, Philadelphia (2006) Dimeglio, A., Bonnel, F.: Le rachis en croissance (The Spinal Column in Growth). Springer, Paris (1990) Dubousset, J., Herring, J.A., Shufflebarger, H.: The crankshaft phenomenon. J. Pediatr. Orthop. 9, 541–550 (1989) Emans, J.B., Caubet, J.F., Ordonez, C.L., et al.: The treatment of spine and chest wall deformities with fused ribs by expansion thoracostomy and insertion of vertical expandable prosthetic titanium rib. Spine 30, S58–S68 (2005) Ganey, T.M., Ogden, J.A.: Development and maturation of the axial skeleton. In: Weinstein, S.L. (ed.) The Pediatric Spine. Principles and Practice, 2nd edn, pp. 3–54. Lippincott Williams & Wilkins, Philadelphia (2001) Gilsanz, V., Boechat, I.M., Birnberg, F.A., et al.: Scoliosis after thoracotomy for esophageal atresia. AJR Am. J. Roentgenol. 141, 457–460 (1983) Hallock, H., Francis, K.C., Jones, J.B.: Spine fusion in young children: a long-term end-result study with particular reference to growth effects. J. Bone Joint Surg. Am. 39, 481–491 (1957) Hefti, F.L., McMaster, M.J.: The effect of the adolescent growth spurt on early posterior spinal fusion in infantile and juvenile idiopathic scoliosis. J. Bone Joint Surg. Br. 65-B, 247–254 (1983) Karol, L.A., Johnston, C., Mladenov, K.: Pulmonary function following early thoracic fusion in non-neuromuscular scoliosis. J. Bone Joint Surg. Am. 90-A, 1272–1281 (2008) Langenskiöld, A., Michelsson, J.E.: Experimental progressive scoliosis in the rabbit. J. Bone Joint Surg. Br. 43-B, 116–120 (1961) Lenke, L.G., Dobbs, M.G.: Management of juvenile idiopathic scoliosis. J. Bone Joint Surg. Am. 89-A, 55–63 (2007) Mayer, O.H., Redding, G.: Early changes in pulmonary function after vertical expandable prosthetic titanium rib insertion in children with thoracic insufficiency syndrome. J. Pediatr. Orthop. 29, 35–38 (2009) McCarthy, R.E., Cullogh, F.L., Luhmann, S.J., Lenke, L.G.: Shilla growth enhancing system for the treatment of scoliosis in children: greater than two year follow-up. Scoliosis research society 43rd annual meeting, Salt Lake (2008) p. 107 Pehrsson, K., Bake, B., Larsson, S., Nachemsson, A.: Lung function in adult idiopathic scoliosis: a 20 year follow up. Thorax 46, 474–478 (1991) Pehrsson, K., Larsson, S., Oden, A., Nachemsson, A.: Long-term follow-up of patients with untreated scoliosis. A study of mortality, causes of death, and symptoms. Spine 17, 1091–1096 (1992) Puisto, V., Kääriäinen, S., Impinen, A., et al.: Incidence of spinal and spinal cord injuries and their surgical treatment in children and adolescents. A population based study. Spine 35, 104–107 (2010) Ramirez, N., Cornier, A.S., Campbell, R.M., Carlo, S., Arroyo, S., Romeu, J.: Natural history of thoracic insufficiency syndrome: a spondylothoracic dysplasia perspective. J. Bone Joint Surg. Am. 89, 2663–2675 (2007)

1  Normal and Abnormal Growth of Spine

13

Ruf, M., Jensen, R., Letko, L., Harms, J.: Hemivertebra resection and osteotomies in congenital spine deformity. Spine 34, 1791–1799 (2009) Sankar, W., Skaggs, D., Yacizi, M., et al.: Lengthening of dual growing rods: is there a law of diminishing returns? Paper #15 presented at 3rd international congress on early onset scoliosis and growing spine, Istanbul, Turkey, 20–21 Nov 2009 Sevastik, J., Agadir, M., Sevastik, B.: Effect of rib elongation on the spine. Spine 15, 822–829 (1990) Shufflebarger, H.L., Clark, C.E.: Prevention of the crankshaft phenomenon. Spine 16(Suppl 8), S409–S411 (1991) Sistonen, S., Helenius, I., Peltonen, J., et  al.: Natural history of spinal anomalies and scoliosis assosiated with esophageal atresia. Pediatrics 124, 1198–1204 (2009) Sponseller, P.D., Yazici, M., Demetracopoulos, C., Emans, J.B.: Evidence basis for management of spine and chest wall deformities in children. Spine 32, S81–S90 (2007) Thurlbeck, W.M.: Postnatal human lung growth. Thorax 37, 564–571 (1982) Winter, R.B.: Scoliosis and growth. Orthop. Rev. 6, 17–20 (1977) Winter, R.B., Moe, J.H.: The results of spinal arthrodesis for congenital spinal deformity in patients younger than five years old. J. Bone Joint Surg. Am. 64-A, 419–432 (1982) Winter, R.B., Moe, J.H., Lonstein, J.E.: Posterior spinal arthrodesis for congenital scoliosis. J. Bone Joint Surg. Am. 66-A, 1188–1197 (1984) Yazici, M., Emans, J.: Fusionless instrumentation system for congenital scoliosis. Expandable spinal rods and vertical expandable prosthetic titanium rib in the management of congenital spine deformities in the growing child. Spine 34, 1800–1807 (2009) Zhang, H., Sucato, D.J.: Unilateral pedicle screw epiphysiodesis of the neurocentral synchondrosis. Production of idiopathic-like scoliosis in an immature animal model. J. Bone Joint Surg. Am. 90-A, 2460–2469 (2008)

 

Part II Evaluation

 

Clinical Evaluation

2

Dror Ovadia

2.1  Medical History Evaluation of a child with scoliosis should begin with a comprehensive and complete history followed by physical examination. The history should begin with prenatal information taken from the parents including health problems, previous pregnancies, medications taken during the pregnancy, and if any sonographic surveillance was performed, whether there were abnormal findings. Inquiries regarding length of gestation, type of delivery, child’s presentation at birth, birth weight, and complications during birth, if any, should also be made (Akbarnia 2007). It is important to have information regarding other medical problems especially of the genitourinary, cardiac, and nervous systems, and also of other musculoskeletal disorders such as DDH, club foot, and brachial plexus injuries (Winter 1983). General information regarding previous operations or illnesses may help to reveal disorders in other organ systems (McCarthy 2001). It is important to ask about developmental milestones and the presence of cognitive delay, difficulties in learning, gait abnormalities, etc. (Wynne-Davies 1975).

2.2  Physical Examination The purpose of the physical examination is both to access the spinal deformity, and to try and eliminate other associated disorders. At this young age group, the child should be examined fully undressed except for underpants. Examination starts with the inspection of

D. Ovadia Department of Pediatric Orthopaedic Surgery, Dana Children’s Hospital, Tel Aviv Sourasky Medical Center, Sackler Faculty of Medicine, Tel Aviv University, 6 Weizman Street, 64239 Tel Aviv, Israel e-mail: [email protected]

M. Yazici (ed.), Non-Idiopathic Spine Deformities in Young Children, DOI: 10.1007/978-3-642-19417-7_2, © 2011 EFORT

17

18

2



D. Ovadia

Fig. 2.1  Port-wine hemangioma is seen around the lower lumbar spine that is indicating an occult spinal dysraphism

the global body balance, the child’s posture and body habitus, symmetry of the limbs, arm spans, and chest or flank asymmetry as well as inspection of the skin for any pigment changes such as café-au-lait spots, axillary or groin freckles as seen in neurofibromatosis (NF), hairy patches, hemangiomas or sinuses along the back midline indicating spinal dysraphism (Fig. 2.1). The clinical plumb-line should be accessed in both coronal and sagittal planes by using a plumb bob. The bob is dropped from the C7 spinous process down and beyond the gluteal crease (Fig. 2.2). In the normal spine it will fall within 1–2 cm of the midline. Global pelvic balance should be examined by palpating both iliac crests and if obliquity and leglength discrepancy (LLD) are suspected, repeating the examination with small wooden blocks underneath the short extremity will allow elimination of the LLD contribution to the pelvic obliquity (Fig. 2.3a, b). The next step should be the evaluation of the range of motion of the spine, the flexibility of the curve, and the amount of rotation as measured by the angle of trunk rotation (ATR) using the scoliometer while the child is positioned in the Adam’s forward-bending test (Fig. 2.4) (Bunnell 1984). The test should be performed twice, once when the examiner is standing directly behind the child, and a second time when looking down from the head toward the buttocks. This can be sometimes difficult in very young children with early

2  Clinical Evaluation

19

Fig. 2.2  Shoulder height inequality, waist asymmetry, and loss of coronal balance are some of the physical features that can be observed during the physical examination of a child with early onset scoliosis

onset scoliosis (EOS) and can be simulated by laying the child in a prone position over the examiner’s knee. Accessing curve flexibility can be evaluated in a similar way by placing the child in a lateral position. Chest excursion should be examined by placing both hands over the child’s chest from behind, and asking the child to take a deep breath (Fig. 2.5a, b). Limitation in chest excursion may indicate syndromic scoliosis or thoracic insufficiency syndrome (Campbell et al. 2003). Next, the child is asked to walk in the room. First in a regular way followed by walking on tip toes and then, walking on heels. This will allow testing most of the muscle function of the lower limbs. The child is then placed supine on an examination table. Limb range of motion is examined to detect either contractures around any of the joints or generalized hyperlaxity (Fig. 2.6a–c). Leg length should be accessed by measuring the distance between the anterior superior iliac spine and the medial malleolus of each leg, and then by repeated measuring of the distance between the umbilicus and the medial malleolus. Differences in both these measurements will detect true LLD, while by measuring of the different lengths between these types of evaluation; a component of pelvic obliquity should be suspected and further investigated.

20

2



Fig. 2.3  Limb-length inequality may be a cause of scoliosis. (a) Scoliosis in this patient was caused due to an overgrowth of the right leg, which was treated with epiphysiodesis of the distal femoral and proximal tibial growth plates. (b) Upon correction of limb-length discrepancy, the scoliotic deformity has also markedly regressed with no other treatment

D. Ovadia

a

b

21

2  Clinical Evaluation Fig. 2.4  A rib hump, thoracic in this figure, will become more prominent with the Adams forward-bending test, as explained in the test

a

b

Fig. 2.5  Thumb excursion test: at rest (a) and inhale (b). During inhalation, while right thumb moves laterally away from the spine, left one stays at the same position because of chest hypokinesia secondary to rib fusion

22

2



D. Ovadia

Fig. 2.6  (a) Hyperlaxity may be associated with scoliosis and its diagnosis depends on several findings. Thumb hyperlaxity is demonstrated in this figure. The patient’s thumb can be painlessly brought to contact the dorsal aspect of the forearm. (b) Another finding of hyperlaxity is the ability to bring the fingers to a position that is parallel to the forearm. (c) Flexible pes planus may be another indicator of generalized hyperlaxity

Finally, the neurologic examination is completed by performing clonus and Babinski testing of the feet, tendon reflex testing on both upper and lower extremities, followed by abdominal reflexes. Absence of this latter reflex may be indicative of underlying neurologic problems (Zadeh et al. 1995). After completing a full physical examination, a radiological evaluation of the child should be carried out (Dobbs 2001, Schwend 1995). The plain radiograph evaluation is discussed in a separate chapter.

2  Clinical Evaluation

23

2.3  Pulmonary Evaluation The pulmonary system can be significantly affected by the structural changes brought about scoliosis and this is one of the reasons for increased morbidity and even mortality in children with EOS. This is due to both intrinsic (amount of alveoli) and extrinsic (thoracic volume) factors. Some of these children with severe deformities might even suffer from thoracic insufficiency syndrome (TIS), defined as the inability of the thorax to support normal respiration & lung growth (Campbell and Smith 2007). The most common respiratory defect in scoliosis is restrictive, with a decrease in vital capacity (VC) and forced expiratory volume in 1 s (FEV1) in correlation with the severity of the deformity. Therefore, it is advisable that all children with EOS should undergo pulmonary evaluation prior to any surgical treatment. Pulmonary function tests are the best means to perform preoperative assessment, yet some of these children are too young to collaborate and successfully perform these tests. In such cases a multispecialty evaluation should be performed separately by the pediatric orthopedist, pediatric pulmonologist, and pediatric anesthesiologist.

2.4  Cardiac Evaluation In patients with congenital anomalies, preexisting morbidities, and those with severe scoliosis curves, the cardiac system might be affected. There can either be primary additional congenital cardiac anomalies or secondary impairment related to the severity of the deformity possibly leading to cor pulmonale. In such cases it is advisable to refer the child to a pediatric cardiologist for examination and to perform investigations including ECG and echocardiogram.

References Akbarnia, B.A.: Management themes in early onset scoliosis. J. Bone Joint Surg. Am. 89, 42–54 (2007) Bunnell, W.: An objective criterion for scoliosis screening. J. Bone Joint Surg. Am. 66, 1381–1387 (1984) Campbell, R.M., Smith, M.D.: Thoracic insufficiency syndrome and exotic scoliosis. J. Bone Joint Surg. Am. 89, 108–122 (2007) Campbell, R.M., Smith, M.D., Mayes, T.C., et  al.: The characteristics of thoracic insufficiency syndrome associated with fused ribs and congenital scoliosis. J. Bone Joint Surg. Am. 85, 399–408 (2003) McCarthy, R.E.: Evaluation of the Patient with Deformity: The Pediatric Spine, 2nd edn. Lippincott Williams & Wilkins, Philadelphia (2001) Winter, R.: Congenital Deformities of the Spine. Thieme-Stratton, New York (1983)

24

2



D. Ovadia

Wynne-Davies, R.: Infantile idiopathic scoliosis. Causative factors, particularly in the first six months of life. J. Bone Joint Surg. Br. 57, 138–141 (1975) Zadeh, H.G., Sakka, S.A., Powell, M.P., Mehta, M.H.: Absent superficial abdominal reflexes in children with scoliosis. An early indicator of syringomyelia. J. Bone Joint Surg. Br. 77, 762–767 (1995)

Radiologic Evaluation of Non-Idiopathic Early Onset Spine Deformities

3

Jorge Mineiro

Very often the diagnosis of an early onset spinal deformity can be diagnosed at birth or very early on in life. The radiological assessment of an early onset spinal deformity will be based either on direct or indirect signs from the clinical observations no matter what the likely diagnosis is – idiopathic or non-idiopathic. However, not all spinal deformities are obvious on clinical examination in very young children. In these cases the physician should be aware of the most common syndromes associated with spinal deformities in order to request the appropriate studies to rule out the presence of such a deformity. In the infantile and juvenile age group with scoliosis several authors have pointed out the high incidence of neural axis abnormalities, despite low frequency of findings on physical observation or clinical history (Lewonowski et al. 1992; Charry et al. 1994; Evans et al. 1996). Scoliosis may occasionally be the first sign of underlying neural axis abnormality in this age group (Gupta et al. 1998). On a routine setup when we see a young child with a spinal deformity we will have to screen the patient carefully in order to be able to identify a cause for a deformity that is not common in this age group. On occasion, the diagnosis may be obvious either from the curvature itself (i.e., congenital scoliosis) or from the underlying condition known to be associated with scoliosis/kyphosis (i.e., VATER syndrome, Rett syndrome, Duchenne muscular dystrophy…). Scoliosis is usually first detected during a standard physical examination by a pediatrician, noticed by a child’s parents, or during a full workup for the child’s underlying condition (i.e., neuromuscular disease). The workup of these children’s scoliosis should follow the same steps as for an idiopathic case, but curve progression in these children is not only dependent on the maturity parameters. Many other factors, related to the underlying condition, play a relevant role in curve aggravation and contribute to a prognosis that is somehow unpredictable.

J. Mineiro Hospital CUF Descobertas, Rua Mario Botas-parque das Nacoes, 1998-018 Lisbon, Portugal e-mail: [email protected]

M. Yazici (ed.), Non-Idiopathic Spine Deformities in Young Children, DOI: 10.1007/978-3-642-19417-7_3, © 2011 EFORT

25

26

3



J. Mineiro

The choice of imaging modality is determined by age and clinical presentation of the child as will be discussed.

3.1  Skeletal Maturity Markers Skeletal maturity is an important issue in order to assess the remaining growth to establish the risk of progression of a spinal deformity. It has indeed several components as chronological age, height and weight changes, and skeletal and sexual maturation. It would be ideal for the physician to have a maturity measurement that would be simple, readily available, and that would correlate with scoliosis progression. The most rapid growth phase corresponds to the accelerating phase of the pubertal growth spurt which is characterized by a gradual increase in the spinal growth rate (Dimeglio 2001). However, we do need to have a more accurate idea on the skeletal bone age and growth remaining for the child that presents in the clinic with spinal deformity – this can be estimated by several techniques that will be subsequently described, with radiographs from different bones in the skeleton. However, when we talk about curve progression in non-idiopathic scoliosis, we have to take into account not only the maturity parameters (and skeletal markers) but also many other issues that are related to the underlying condition (i.e., neuromuscular scoliosis). In these cases the natural history of curve progression in the sagittal plane is even less well defined and predictable than scoliosis. The rate of scoliotic curve progression does vary among the different conditions and although aggravation is common in both cerebral palsy (CP) and Duchenne muscular dystrophy, in some of the CP children curves may develop very early on (before 8 years) and may require treatment between 4 and 6 years of age. In children with severe spinal muscular atrophy, scoliosis may become fixed by 6–8 years of age and when we look at paralytic curves, most of them remain flexible and do not progress beyond 90° until the adolescent growth spurt. The behavior of curve progression in non-idiopathic scoliosis is difficult to predict as each case has its own particularities that are related to the underlying condition and also to the child’s age. Physicians looking after these patients need to be aware of skeletal markers in order to help treating of these unfortunate children.

3.1.1 Risser Sign Determination of skeletal age is an important issue for the planning of surgical/conservative treatment as well as for establishing the prognosis of spinal deformities in young children. Skeletal age relies on the fact that bones grow and physes mature in an orderly sequence. The most used skeletal marker for patients with scoliosis is the iliac apophysis. However, many other regions of the skeleton can be used for the same purpose like the pelvis, the hand, the knee, and the elbow. The Risser sign is based on the radiographic excursion of the iliac crest apophyseal ossification. It starts at the antero-superior iliac spine and progresses ­posteriorly to the

3  Radiologic Evaluation of Non-Idiopathic Early Onset Spine Deformities

27

postero-superior iliac spine. Risser sign has been modified to distinguish phases of maturation of the iliac apophysis by dividing the crest into four quarters on the antero-posterior radiograph of the pelvis. As the ossification progresses to grade IV, a cap covers the whole crest and in grade V the apophysis is completely fused to the iliac crest and is a sign of complete maturity. However, during the last phase of growth the Risser sign remains grade 0 for a large period of time. Risser grade I only appears by 13.5 years of skeletal age in girls and 15.5 years in boys (Dimeglio 2001). The iliac apophysis does not begin to show ossification until on average 18 months after the curve acceleration phase, meaning that most curve progression has occurred well before Risser I grade is evident on radiographs (Sanders et al. 2007). Taken into account these facts, the iliac apophysis as skeletal marker does not help spine surgeons to distinguish maturity levels prior to Risser grade I. Regarding imaging the Risser sign, Isumi (1995) pointed out the discrepancy of the radiographs used to assess the iliac apophyses – postero-anterior or antero-­posterior – due to the radiographic parallax of the x-ray beam with the pelvic brim. Although the Risser sign is a simple, easily available method for assessing skeletal maturity, it should be used cautiously when more accurate skeletal maturity determination is required (Fig. 3.1).

Fig. 3.1  Risser sign (difficult accurate assessment and large field radiation exposure)

28



J. Mineiro

3

Fig. 3.2  (a – c) Triradiate cartilage closure during Risser 0

3.1.2  Triradiate Cartilage The closure of the triradiate cartilage can split approximately the Risser grade 0 in two halves as it occurs around the skeletal age of 12 years in girls and 14 years in boys (Dimeglio 2001). Triradiate cartilage closure (Fig. 3.2) has been used for the purpose of assessing the risk for crankshaft phenomenon after posterior spinal fusion in young patients with immature spines (Sanders et al. 1995; Shufflebarger and Clark 1991; Sanders et al. 1997; Roberto et al. 1997).

3.1.3  The Sauvegrain Method (Olecranon Method) The Sauvegrain method for the assessment of skeletal age has been used in France for the past decades (Sauvegrain et al. 1962). It uses lateral radiographs of the elbow during the accelerating phase of pubertal growth spurt from the skeletal age of 11–13 in girls and from

29

3  Radiologic Evaluation of Non-Idiopathic Early Onset Spine Deformities 7 Points 6.5 Points 6 Points 5 Points 3 Points

Risser I Triradiate cartilage closure

11

11.5

12

12.5

13

Girls

18 years

13

13.5

14

14.5

15

Boys

18 years

Fig. 3.3  Sauvegrain method (Olecranon method) (Courtesy of A. Dimeglio)

13 to 15 in boys. Complete ossification of the elbow ossification centers coincides with the end of the accelerated growth velocity and marks the commencement of the decelerating growth phase (Dimeglio et al. 2005) (Fig. 3.3). Dimeglio et al. (2005) have simplified the Sauvegrain method in order to allow skeletal age to be evaluated by simple assessment of this apophysis at regular intervals of 6 months. Skeletal age can be assessed by grading of the olecranon apophysis from the ages of 11 to 13 in girls and from 13 to 15 in boys at 6-month intervals. These five different phases start at 11  years of age with the two ossification centers that progress to form a rectangular ossification center in shape by the age of 12 in girls and goes on to fuse to the ulna shaft by the age of 13 in girls (15 in boys). As in children with juvenile idiopathic scoliosis, the spinal deformity may develop prior to the pubertal growth spurt during Risser 0, which is the phase where 90% of the surgically treated curves do increase (Charles et al. 2006). During the long Risser 0 phase, the olecranon ossification center may help to identify immature patients with scoliosis who are at risk of developing crankshaft phenomenon (the two early phases with two ossification centers or a half moon–shaped nucleus of the olecranon on the lateral radiograph) (Sanders et  al. 1995; Sanders et  al. 1997; Shufflebarger and Clark 1991; Roberto et  al. 1997; Hefti and McMaster 1983; Dubousset et al. 1989).

3.1.4  Digital Skeletal Age (DSA) Sanders et al. (2007) pointed out that although all four methods for determining skeletal maturation (the Tanner-Whitehouse-III RUS method, the Greulich and Pyle method, the Oxford method, and the Risser Sign) correlated significantly with the curve ­acceleration

30



J. Mineiro

3

f (covered) g (capped) Tanner-Whitehouse III Stages

Fig. 3.4  Tanner-Whitehouse III maturation stages – proximal middle phalanx changes

phase (CAP), the weakest of all was the Risser Sign. In all his patients, the CAP began during the Risser phase 0. From the individual bone ­components of the RUS method, the radius and ulna had the lowest correlation to the curve acceleration phase. They tested the RUS method without the radius and ulna, using the phalanx and termed the method Digital Skeletal Age (DSA). Radiographically, the timing of the curve acceleration phase corresponded to the change from a covered to a capped phalangeal epiphysis (TannerWhitehouse-III stage F to stage G) (Tanner 1959) (Fig.  3.4). In this method the carpal scores reached maturity at the time of the curve acceleration phase (Sanders et al. 2007). Although the Sanders study was performed in girls, it is likely that the stage of skeletal maturity will also be a strong predictor of curve progression in boys (Sanders et al. 2007). Although a significant correlation between the Tanner-Whitehouse-III method and curve acceleration phase was shown, DSA score in particular appears to provide a more predictive maturity determination, identifying the period of maximum curve deterioration risk (Sanders et al. 2007).

3  Radiologic Evaluation of Non-Idiopathic Early Onset Spine Deformities

31

3.2  Conventional Radiography 3.2.1  Plain Radiographs The initial evaluation of a child with a suspected spinal deformity should consist of postero-anterior and lateral radiograph of the entire spine, including the cervical spine and the pelvis. Measurement of a scoliosis curvature is by the Cobb technique (Cobb 1948), as has been the rule for past decades. For those children that are not yet able to stand, the radiographs should be taken with the child lying supine, insuring that the upper cervical and lumbosacral areas are included in the images. When children start walking, the spinal radiologic assessment should be preferably in the standing position, or taken sitting if they are not able to stand independently. Standing postero-anterior and lateral spine radiographs should be requested in order to document the curve size, to rule out congenital abnormalities, and to serve as a baseline for monitoring future progression. Lateral views of the spine standing should be done with the arms raised forward 45° as pointed out by Stagnara in order not to modify the lordosis or kyphosis (Stagnara et al. 1982) or with the fingertips on the clavicles as protocol in many centers (BrAIST). In the past, con ed-down oblique views of the apex of the curve were routinely obtained to give a good antero-posterior view of the rotated vertebra and would help detecting hidden skeletal abnormalities. Today these views have been replaced by Computed Tomography (CT) reconstruction that gives the surgeon a two-dimensional reformatting or a three-dimensional reconstruction image that can be manipulated to give the treating physician more information about the deformity. In most cases of early onset scoliosis, the chest dimensions and mechanics must be taken into consideration. With aggravation of the scoliosis, the thoracic asymmetry deteriorates, decreasing the height of the thoracic spine (defining the height of the thorax) and the height of the concave hemithorax will be more affected. Although aggravation of the scoliosis can be assessed on a plain radiograph by an increase in the Cobb angle and rotation of the vertebral bodies in the curvature, it will not give the spatial dimension of the deformity and its effect on the thoracic function compromise. In these cases, it is important to assess the space available for the lungs; this estimate can be given by measuring the ratio (in percentage) of the height of the concave hemithorax compared with that of the convex hemithorax (Campbell et al. 2003). With modern imaging techniques the asymmetry between hemithoraces, as part of the thoracic deformity, can be assessed more accurately through CT. CT should therefore be considered part of the workup in the radiologic evaluation of these children with early onset spine deformities independent of its etiology as discussed later.

32

3



J. Mineiro

3.2.2  Flexibility/Instability Testing 3.2.2.1  Bending/Traction Films Once the decision has been made for the surgical management of scoliosis, the next step will be to determine which area of the spine needs to be incorporated into the fusion area. Although we realize that the vertebrae in the scoliotic curve need to be fused, should it be from end-to-end vertebra (Bute 1938), from neutral-to-neutral vertebra (Moe 1972; Golstein 1964) or should the fusion stop at the stable zone (Harrington 1972; King et al. 1983)? These criteria were developed prior to the introduction of modern segmental fixation systems which can be used anteriorly or posteriorly. Despite controversy and different opinions, all criteria are based on the flexibility of the scoliotic curvature. This can be assessed either by bending or traction films. These films will provide not only information on the rigidity of the curves but also on the amount of correction that can be achieved safely and whether or not a secondary curve should be included in the initial fusion. Side-bending films can be done either standing or supine. A bending film is usually done with maximal active side bending in the supine position and separate films should be obtained for each side (left and right bending) (Fig. 3.5). Occasionally, forceful bending may be used for special cases such as in neuromuscular scoliosis. The controversy on sidebending films being done standing or supine was answered by several studies in the early 1990s showing supine films to be better in demonstrating curve flexibility (Shufflebarger 1992; Transfeld et al. 1992).

Fig. 3.5  Supine side bending films

3  Radiologic Evaluation of Non-Idiopathic Early Onset Spine Deformities

33

Fig. 3.6  Traction films on the x-ray table in CP patient

More recently, traction films have replaced the use of the side-bending films according to several authors. These can either be done on a Risser table, x-ray table (Fig. 3.6) or in certain cases on the operating table under general anesthetics for severely handicapped children that cannot cooperate with this maneuvre (i.e., patients with neuromuscular scoliosis or mental retardation) (Hamzaoglu et al. 2005). As was pointed out by Vaughan (1996), supine sidebending films proved to be more effective for selection of fusion levels than Risser table traction films in the case of scoliotic curvatures with a Cobb angle <60°. Traction was more effective for those curvatures with a Cobb angle greater than 60°. However side-bending films are obviously effort dependent and to make sure they are properly done, these films should be supervised when taken but even so, it does require patient cooperation. Fulcrum-bending films performed with a wedge under the curve convexity with patients lying on the side is another method of assessing curve rigidity and can be more predictive of the degree of flexibility and correctability than ­side-bending films according to Cheung (1997) and Luk (2008). However, not all children with scoliosis or kyphosis are able to withstand this position on their own. Fulcrum-bending films do require patient’s cooperation (used in adolescent idiopathic scoliosis) and may not be suitable for most young children with early onset scoliosis or any other less cooperative youngster.

34

3



J. Mineiro

3.3  Spinal Deformity Measurement 3.3.1  Cobb Angle Measurement of scoliosis curvature through the Cobb technique (1948) is used not only for the initial evaluation but also for monitoring of spinal curve progression in the future. According to the technique, the Cobb angle is measured between the endplates of the two end vertebrae (superior and inferior) on a single plane AP spine radiograph. As a single plane radiograph measurement it fails to account for vertebral rotation as it may not accurately demonstrate the severity of three-dimensional spinal deformity. The preselection of the end vertebrae using the same measuring tools for all radiographs may help reduce measurement error and therefore should be a rule to adopt whenever we have a case of early onset spinal deformity. At present, a great number of hospitals have digital radiographs that allow us a computerized measurement that may also help to reduce the measurement error induced by a pencil or marker. However, it is the magnitude of the curvature measured by the Cobb angle that is the basis for decision making in the management of the spinal deformity. Despite the interobserver and intraobserver variability reported (from 2.6 to 8.8), it is undoubtedly an important method for the assessment of any of these early onset spinal conditions. Measurement variability in adolescent idiopathic scoliosis (Carman et  al. 1990; Desmet et  al. 1982; Morrissy et al. 1990; Ylikoski and Tallroth 1990) and congenital scoliosis (Facanha-Filho et al. 2001; Loder et al, 1995) have already been reported, but in children younger than 10 years of age with noncongenital scoliosis, Loder et  al. (2004) pointed out that there must be a change of at least ±7° to demonstrate significant progression. Regarding the frequency of follow-up radiographs in these young children with spinal deformities there is no strict rule but it would be reasonable if the child has a rapidly progressive curve, to repeat the radiographs in periods of 4–6 months. But if on the contrary, the curve is only minimally progressive, then repeat radiographs every 6 months or longer would be acceptable (Morrissy et  al. 1990; Ylikoski and Tallroth 1990; Carman et  al. 1990; Desmet et al. 1982). However, 4-month intervals are very short periods and radiographic changes are often not accurate enough for the physician to base his or her decisions. As far as radiation is concerned, we need to be aware that a 4-month interval would also mean that these children would have a greater number of radiographs and radiation exposure until the final procedure.

3.3.2  Spinal Penetration Index (SPI) In 2003, Dubousset et al. (2003) reported on a deformity – vertebral body protrusion – that although part of three-dimensional scoliotic deformity could not be understood in terms of the more common Cobb angle measurement of scoliosis. This type of deformity has been

3  Radiologic Evaluation of Non-Idiopathic Early Onset Spine Deformities

35

the cause of airway compression by vertebral bodies in the very severe thoracic scoliosis. Although apical lordosis of the thoracic spine is a constant finding in lordoscoliosis with the thoracic spine protruding into the chest cavity, the relevance of the antero-posterior diameter of the thorax relies on the indirect compromise of the vital capacity as has been stressed by Geyer (1998). Based on these findings, the SPI has been developed as a morphologic measurement that quantifies the penetration of the vertebral bodies and surrounding structures in relation to the theoretical thoracic room calculated from a tangent to the right and left posterior ribs (Dubousset et al. 2003). The SPI can be divided in two patterns – Spinal Penetration Index Surface (SPIS) which is a two-dimensional measurement, and a Spinal Penetration Index Volume (SPIV) which is three-dimensional, both measuring the penetration of the spine and other accompanying structures inside the rib cage (Dubousset et al, 2003). In a normal chest, SPIV can vary between 7% and 10% but in a severe lordoscoliosis it can increase to values of 18%, 26%, or more and in the case of SPIS it may reach 50% or even more. Both SPIS and SPIV should be used to compare the results between the preand postoperative period. Despite a good postoperative correction of the scoliosis curvature seen on the x-rays, when we think at the three-dimensional scale the results are very often not as obvious and the improvement in the SPIV is also less evident. Dubousset et al. also defined the concept of two types of humps in thoracic ­scoliosis – the visible, cosmetic rib hump and the hidden or functional vertebral hump (Dubousset et al. 2003). The visible or cosmetic rib hump which is the result of displacement of the rib and the spine due to the axial rotation of the scoliotic thoracic spine can be measured by tangential radiographs and surface three-dimensional topography. The technique for assessment of this deformity, determining the volume in excess on the convex side of the curve (exothoracic rib hump) (Fig. 3.7a) and the volume deficit on the concave side of the curve (exothoracic missing hump) (Fig.  3.7b), and the values would be determined by comparing it with the ideal normal transverse plane contour (Fig. 3.7). These findings can be used on clinical grounds helping out the surgeon on the decision to add any other procedure for the “hump” management. For a common adolescent idiopathic scoliosis with a moderate exothoracic convex rib hump with a 10°–12° smooth slope on an inclinometer, no particular treatment is needed for the hump but only for the spine and this can either be

Fig. 3.7  Spinal penetration index (Courtesy of J. Dubousset)

36

3



J. Mineiro

through the front or back. Good correction of the spine rotation can improve the cosmesis generally by 50% or more. For the more severe thoracic scoliosis with an inclinometer of 15°–20° and a significant exothoracic concave missing hump, a classical convex thoracoplasty in addition to posterior spinal instrumentation and fusion (either with or without an anterior release for prevention of the crankshaft phenomenon) should be done. In the most severe cases, with severe exothoracic rib humps, thoracoplasty on the concave side may be used to lift up the ribs and a rod can be placed in front of the ribs as was pointed out by Stagnara (1985). For the cases with a significant endothoracic vertebral hump and compression of the airway, it is required to perform an osteotomy with anterior resection of part of the vertebral bodies together with a posterior spinal instrumentation and fusion for decompression of the bronchi. In these patients hyperlordosis should be diagnosed early in order to prevent airway compromise and in the very young an anterior ­epiphysiodesis should be considered (Dubousset et al. 2003) to prevent aggravation of the vertebral body protrusion.

3.4  Computed Tomography (CT) For some complex early onset deformities, in particular congenital scoliosis (Fig. 3.8b), after removal of a spinal cord tumour (Fig 3.8a) or syndromic cases (Fig 3.8c and d), the CT provides a more detailed view of the deformity with an increased accuracy in defining the bony deformity as compared to the plain radiographs. With the modern CT equipment, at the expense of an increased radiation exposure, it is possible to obtain three-dimensional reconstruction images. These films help a great deal to understand complex deformities and are also extremely helpful in establishing the surgical strategy for the preoperative planning for correction of these curves. In the more complex type of congenital spinal malformation, these abnormalities had been classified as formation failures according to conventional classification (Winter 1983; Winter et  al. 1968) based on plain radiographs, but three-dimensional analysis demonstrated many other conventionally unknown structures, suggesting a new malformation concept for this condition. This computerized analysis demonstrated posterior components of the malformed vertebrae which differed from the malformed anterior vertebrae and none of these abnormalities could be seen on the single plane radiology (Nakajima et al. 2007) (Fig. 3.8a). Advanced CT imaging (three-dimensional and curved/standard multiplanar reformatted images) allows a better understanding of some of these complex congenital spinal anomalies. In more than 50% of cases it has shown other components of these malformations that had not been identified before, either on plain radiology or on axial two-dimensional CT (Newton et al. 2002). Another use of CT in the study of these early onset scoliosis is determining the extent of the chest wall deformities associated with these spinal deformities and in estimating the of preoperative lung volumes, particularly in the very young. In the case of posterior chest wall deformities, the use of the three-dimensional reconstruction helps to understand its relation to the spinal deformity.

3  Radiologic Evaluation of Non-Idiopathic Early Onset Spine Deformities

37

Fig. 3.8  Spinal and Chest Computed Tomography (CT) in scoliosis of different aetiologies

Certain congenital scoliosis with severe spinal angulation and rotation may compromise thoracic function and growth as has been pointed out by Campbell (2003). However, the rotational component of the spinal deformity associated to another congenital abnormality of the chest wall, fused ribs, may induce severe distortion of the rib cage that requires a three-dimensional thoracic investigation. Three-dimensional loss of thoracic symmetry is difficult to assess on conventional radiographs and, therefore, can be measured by CT. When evaluating these sick children in the clinic it may not be difficult to assess deterioration of the spinal deformity but it may be more troublesome to estimate the worsening thoracic asymmetry. Measuring deterioration of the thoracic rotation by the

38

3



J. Mineiro

increase in the angular relationship of the sternum to the sagittal plane of the spine may be one of the techniques to use in the clinic. Another method that has been described earlier (Dubousset et al. 2003) is the SPI assessing the reduced sagittal depth of the thorax and subsequent loss of thoracic volume and symmetry (Fig. 3.8c). With advanced CT imaging studies such as three-dimensional reconstructions and transverse cut, images provide (Fig.  3.8a), an additional complement to the plain chest radiographs and give the treating surgeon the three-dimensional thoracic deformity.

3.5  Magnetic Resonance Imaging The association between idiopathic scoliosis and craniovertebral abnormalities is well recognized. With the development of Magnetic Resonance Imaging (MRI), neural axis abnormalities, syringomyelia, and Chiari malformations are increasingly identified in children with scoliosis (even in idiopathic scoliosis). Although scoliosis can sometimes be the presenting sign in some of these conditions, very often the neurologic examination does not identify any abnormality (Park et al. 1997). Charry (1994) reported on 25 young patients with scoliosis with neural axis abnormalities but of these, 40% had very mild neurologic findings and the rest of them were asymptomatic. On the other hand, the risk of neurologic complications in scoliosis surgery increases if these children are not screened appropriately (Nordeen et al. 1994). Although neurologically intact children with scoliosis may not need preoperative MRI, there are indeed certain patients at risk for which we should be aware. Children with juvenile-onset scoliosis (younger than 11 years at first visit), male gender, thoracic kyphosis >30°, leftsided curves (thoracic or thoracolumbar), presence of pain, neurologic deficit including absent or asymmetrical abdominal reflexes, absent gag reflex (Inoue et al. 2004), rapidly progressive curves, and severe curvatures in ­skeletally immature patients (Morcuende et  al. 2003; Barnes et  al. 1993) are a matter of concern and should be screened carefully and an MRI scan should be considered. According to Morcuende et al. (2003), the risk of neural axis abnormality increases if several of these features are presented together in the same patient. Dobbs et  al. in a large multicentered study (Dobbs et  al. 2002) have shown a 21.7% prevalence of neural axis abnormalities in otherwise asymptomatic children with infantile scoliosis and there was no correlation between the MR images, gender, curve magnitude, curve location or curve direction. When evaluating young children with spinal deformities, the orthopedic/pediatric surgeon should be aware of the high risk of neural axis abnormalities that some of these patients have, in order to do the appropriate investigations needed before embarking on a more aggressive form of treatment for the scoliosis. It is a matter of concern the fact that >50% of children with idiopathic scoliosis and abnormalities on the MRI, will need a neurosurgical intervention between birth and the age of 10 years (Lewonowski et al. 1992; Charry et al. 1994; Gupta et al. 1998); therefore, within the same period of time progressive scoliosis may need surgical treatment, reinforcing the need for a proper screening of any atypical scoliosis.

3  Radiologic Evaluation of Non-Idiopathic Early Onset Spine Deformities

39

Fig. 3.9  Magnetic Ressonance Imaging of the Lumbar Spine

MRI should also be an essential part of the evaluation in congenital spinal deformity and special attention should be paid to those cases with segmentation defects, mixed defects, and kyphosis (Basu et al. 2002) in order to rule out associated neural axis abnormalities (Fig. 3.9). For these patients with early onset spinal deformities and indication for an MRI scan, a T1- and T2-weighted sagittal screening images of the cervical, thoracic, and lumbosacral spine together with an additional sagittal and axial screening images of the craniocervical junction, cervicothoracic junction, thoracolumbar junction, ­lumbosacral junction, and the area of major deformity should be performed. Children with scoliosis and suspected spinal dysraphism should undergo routinely axial T1-weighted images through the conus and filum terminal in order to detect lipomas of the filum terminal (Fig. 3.9b and c), spinal cord tethering (Fig.3.9a), that could otherwise be missed on the saggital imaging (Saunders et al. 2007).

References Barnes, P., Brody, J., Jaramillo, D., Akbar, J., Emans, J.: Atypical idiopathic scoliosis: MR imaging evaluation. Radiology 186, 247–253 (1993) Basu, P., Elsebaie, H., Nordeen, M.: Congenital spinal deformity. Spine 27(20), 2255–2259 (2002) BrAIST: Bracing in adolescent idiopathic scoliosis trial. Clinical trials.gov identifier NCT00448448 (2011) Bute, F.L.: Scoliosis treated by the wedging jacket: selection of the area to be fused. J. Bone Joint Surg. 20, 1–22 (1938) Campbell, R., Smith, M., Mayes, T., Mangos, J., Willey-Courand, D., Kose, N., Pinero, R., Alder, R., Duong, H., Surber, J.: The characteristics of thoracic insufficiency syndrome associated with fused ribs and congenital scoliosis. J. Bone Joint Surg. 85A, 399–408 (2003a)

40

3



J. Mineiro

Campbell, R., Smith, M., Mayes, T., Mangos, J., Kose, N., Pinero, R., Alder, M., Duong, H., Surber, J.: The characteristics of thoracic insufficiency syndrome associated with fused ribs and congenital scoliosis. J. Bone Joint Surg. 85A, 399–408 (2003b) Carman, D., Browne, R., Birch, J.: Measurement of scoliosis and kyphosis radiographs, interobserver and interobserver variations. J. Bone Joint Surg. 72A, 328–333 (1990) Charles, Y., Daures, J., de Rosa, V., Dimeglio, A.: Progression risk of idiopathic juvenile sclosiosis during pubertal growth. Spine 31, 1933–1942 (2006) Charry, O., Koop, S., Winter, R., Lonstein, J., Denis, F., Bailey, W.: Syringomyelia and scoliosis: a review of twenty five pediatric patients. J. Pediatr. Orthop. 14, 309–317 (1994) Cheung, K., Luk, K.: Prediction of correction of scoliosis use of fulcrum bending radiograph. J. Bone Joint Surg. 79A, 1144–1150 (1997) Cobb, J.R.: Outline for the study of scoliosis. Instr. Course Lect. 5, 261–275 (1948) Desmet, A., Goin, J., Asher, M.: A clinical study of the difference between the scoliotic angles measured on the posteroanterior and anteroposterior radiographs. J. Bone Joint Surg. 64A, 489–493 (1982) Dimeglio, A.: Growth of pediatric orthopaedics. J. Pediatr. Orthop. 21, 549.55 (2001) Dimeglio, A., Charles, Y., Daures, J., de Rosa, V., Kaboré, B.: Accuracy of the Sauvegrain method in determining skeletal age during puberty. J. Bone Joint Surg. 87A, 1689–1696 (2005) Dobbs, M., Lenke, L., Szymanski, D., Morcuende, J., Weinstein, S., Bridwell, K., Sponseller, P.: Prevalence of neural axis abnormalities in patients with infantile idiopathic scoliosis. J. Bone Joint Surg. 84A, 2230–2234 (2002) Dubousset, J., Herring, J., Shufflebarger, H.: The crankshaft phenomenon. J. Pediatr. Orthop. 9, 541–550 (1989) Dubousset, J., Wicart, P., Pomero, V., Barois, A., Estournet, B.: Spinal penetration index: new three-dimensional quantified reference for lordoscoliosis and other spinal deformities. J. Orthop. Sci. 8, 41–49 (2003) Evans, S., Edgar, M., Hall-Craggs, M., Powell, M., Taylor, B., Noorden, H.: MRI of “idiopathic” juvenile scoliosis. J. Bone Joint Surg. 78B, 314–317 (1996) Facanha-Filho, F.M., Winter, R., Lonstein, J., Koop, S., Novacheck, T., L’Heureux, E., Cheryl, N.: Measurement accuracy in congenital scoliosis. J. Bone Joint Surg. 83A, 42–45 (2001) Geyers B., Lemerrer Y – Le thorax scoliotique: les contraintes horizontal – la scoliose 20 ans de recherche et d’experimentation. Monpellier GKTS Sauramps Medical (1998) Golstein, L.A.: The surgical management of scoliosis. Clin. Orthop. Relat. Res. 35, 95–115 (1964) Gupta, P., Lenke, L., Bridwell, K.: Incidence of neural axis abnormalities in infantile and juvenile spinal deformities. Spine 23(2), 206–210 (1998) Hamzaoglu, A., Talu, U., Tezer, M., Mirzanl, C., Domanic, U., Goksan, S.: Assessment of curve flexibility in adolescent idiopathic scoliosis. Spine 30(14), 1637–1642 (2005) Harrington, P.R.: Technical details in relation to the successful use of instrumentation in scoliosis. Orthop. Clin. North Am. 3, 49–67 (1972) Hefti, F., McMaster, M.: The effect of the adolescent growth on early posterior spinal fusion in infantile and juvenile idiopathic scoliosis. J. Bone Joint Surg. 65A, 247–254 (1983) Inoue, M., Minami, S., Nakatama, Y., Otsuka, Y., Takaso, M., Kitahara, H., Tokunaga, M., Isobe, K., Moriya, H.: Preoperative MRI analysis of patients with idiopathic scoliosis. Spine 30(1), 108–114 (2004) Isumi, Y.: The accuracy of Risser staging. Spine 20, 1868–1870 (1995) King, H., Moe, J., Bradford, D., Winter, R.: Selection of fusion levels in thoracic idiopathic scoliosis. J. Bone Joint Surg. 65A, 1302–1313 (1983) Lewonowski, K., King, J., Nelson, M.: Routine use of magnetic resonance imaging in idiopathic scoliosis patients less than eleven years of age. Spine 17(6 Suppl), 109–116 (1992)

3  Radiologic Evaluation of Non-Idiopathic Early Onset Spine Deformities

41

Loder, R., Urquhart, A., Graziano, S., Hensinger, R., Schlesinger, A., Schork, M., Shyr, Y.: Variability in Cobb angle measurement in children with congenital scoliosis. J. Bone Joint Surg. 77B, 736–738 (1995) Loder, R., Spiegel, D., Gutknetch, S., Kleist, K., Ly, T., Mehbod, A.: The Assessment of interobserver and intraobserver error in the measurement of noncongenital scoliosis in children £ 10 years of age. Spine 29(22), 2548–2553 (2004) Luk, K., Don, A., Chong, C., Wong, Y., Cheung, K.: Selection of fusion levels in fulcrum in adolescent idiopathic scoliosis using fulcrum bending prediction. Spine 33(20), 2192–2198 (2008) Moe, J.H.: Methods of correction and surgical technique in scoliosis. Orthop. Clin. North Am. 3, 17–48 (1972) Morcuende, J., Dolan, L., Vasquez, J., Jirasiraku, A., Weinstein, S.: A prognostic model for the presence of neurologic lesions in atypical idiopathic scoliosis. Spine 29(1), 51–58 (2003) Morrissy, R., Goldsmith, G., Hall, E.: Measurement of Cobb angle on radiographs of patients who have scoliosis: intrinsic error. J. Bone Joint Surg. 72A, 320–327 (1990) Nakajima, A., Kawakami, N., Imajana, S., Tsuji, T., et al.: Three dimensional analysis of formation failure in congenital scoliosis. Spine 32(5), 562–567 (2007) Newton, P., Hahn, G., Fricka, K., Wenger, D.: Utility of three dimensional and multiplanar reformatted computed tomography for evaluation of pediatric spine abnormalities. Spine 27(8), 844–850 (2002) Nordeen, M., Taylor, Edgar B – Syringomyelia: a potential risk factor in scoliosis surgery. Spine 19(12), 1406–1409 (1994) Park, J., Gleason, P., Madson, J.: Presentation and management of Chiari I malformation in children. Pediatr. Neurosurg. 26, 190–196 (1997) Roberto, R., Lonstein, J., Winter, R., Denis, F.: Curve progression in Risser stage 0 or 1 patients after posterior spinal fusion for idiopathic scoliosis. J. Pediatr. Orthop. 17, 718–725 (1997) Sanders, J., Herring, J., Browne, R.: Posterior arthrodesis and instrumentation in immature (Risser grade 0) spine in idiopathic scoliosis. J. Bone Joint Surg. 77A, 39–45 (1995) Sanders, J., Little, D., Richards, B.: Prediction of the crankshaft phenomenon by peak height velocity. Spine 22, 1352–1357 (1997) Sanders, J., Browne, R., Connell, S., Margraf, S., Cooney, T., Finegold, D.: Maturity assessment and curve progression in girls with idiopathic scoliosis. J. Bone Joint Surg. 89A, 64–73 (2007) Saunders, D., Thompson, C., Gunny, R., Jones, R., Cox, T., Chong, W.: Magnetic resonance imaging protocols for paediatric neuroradiology. Pediatr. Radiol. 37, 789–797 (2007) Sauvegrain, J., Nahum, H., Bronstein, H.: Etude de la maturation osseuse du coude. Ann Radiol (Paris) 5, 542–550 (1962) Shufflebarger, H., Clark, C.: Prevention of the crankshaft phenomenon. Spine 16(8 Suppl), S409–S411 (1991) Shufflebarger, H.: Comparison of erect vs. supine bending radiographs for correction of coronal and axial deformity in idiopathic scoliosis. In: Proceeding of the 1st International Symposium on 3-D Scoliotic Deformities, Gustav Verlag, Stuttgart, 1992 Stagnara, P.: Les deformations du rachis. Masson, Paris (1985) Stagnara, P., De Mauroy, J., Dran, G., Gonon, G., Costanzo, G., Dimmet, J., Pasquet, A.: Reciprocal angulation of vertebral bodies in a saggital plane: an approach to references for the evaluation of kyhosis and lordosis. Spine 7, 335–342 (1982) Tanner, J.M.: Assessment of Skeletal Maturity and Prediction of Adult Height. TW3 Method, 3rd edn. Stanford University, London (1959) Transfeld, E.E., Winter, R.B.: Comparison of supine and standing bending films in idiopathic scoliosis to determine curve flexibility. In: Scoliosis Research Society, 26th annual meeting Proceedings. Kansas, 23–26 Sept 1992

42

3



J. Mineiro

Vaughan, J., Winter, R., Lonstein, J.: Comparison of the use of supine bending and traction radiographs in the selection of the fusion area in adolescent idiopathic scoliosis. Spine 21(21), 2469–2473 (1996) Winter, R., Moe, J., Eilers, V.: Congenital scoliosis: a study of 234 treated and untreated. J. Bone Joint Surg. 50A, 1–47 (1968) Winter, R., Lonstein, J.E., Leonard, A.: Congenital Deformities of the Spine, pp. 1–17. ThiemeStratton, New York (1983) Ylikoski, M., Tallroth, K.: Measurement variation in scoliotic angle, vertebral rotation, vertebral body height and intervertebral disc space height. J. Spinal Disord. 3, 387–391 (1990)

Part III Deformities

 

Congenital Deformities of the Spine

4

Athanasios I. Tsirikos

4.1  Introduction Congenital deformities of the spine constitute a gradually blending spectrum of deformities, ranging from a congenital scoliosis through kyphoscoliosis to a pure kyphosis. They are due to an asymmetrical failure of development of one or more vertebrae resulting in a localized imbalance in the longitudinal growth of the spine and an increasing spinal curvature affecting the coronal and/or the sagittal plane, which continues to progress until skeletal maturity (McMaster and Ohtsuka 1982; McMaster and Singh 1999; Winter et al. 1968, 1973). The unbalanced development of the spine across the levels of the congenital vertebral abnormalities can create a benign curve with slow or no progression during growth which may not require treatment other than observation. In contrast, certain types of congenital anomalies affecting the vertebral column may produce a relentlessly aggressive deformity which can result in cosmetic, functional, respiratory, and neurological complications and which necessitates early treatment. Understanding the nature and pathological anatomy of these abnormalities will allow the clinician to determine prognosis in terms of likelihood and rate of deformity progression and this will permit early instigation of appropriate treatment. Congenital scoliosis is the most common type of deformity with a prevalence of 80% among 800 patients with congenital deformities of the spine included in the Scottish Spinal Deformity Registry. Congenital kyphoscoliosis is the second most common type of deformity affecting 14% of patients with congenital kyphosis being rarer and only occurring in 6% of our patients.

A.I. Tsirikos Consultant Orthopaedic and Spine Surgeon, Honorary Clinical Senior Lecturer-University of Edinburgh Clinical Lead, Scottish National Spine Deformity Center, Royal Hospital for Sick Children, Sciennes Road, Edinburgh, EH9 1LF, UK e-mail: [email protected] M. Yazici (ed.), Non-Idiopathic Spine Deformities in Young Children, DOI: 10.1007/978-3-642-19417-7_4, © 2011 EFORT

45

46

4



A.I. Tsirikos

4.2  Embryological Development of the Spine, Ribs, and Scapula The embryological development of the spine and ribs are very closely associated and the complete anatomical pattern is formed in mesenchyme during the first 6 weeks of intrauterine life. Developmental abnormalities of the spine and ribs may occur during this period and once the mesenchymal mold is established, the cartilaginous and bony stages follow that pattern. Vertebral anomalies occurring during the mesenchymal stage may be due to either a unilateral defect of formation or segmentation of the primitive vertebrae and can result in a unilateral imbalance in the longitudinal growth of the spine producing a congenital scoliosis (Tsou 1977; Tsou et al. 1980). Vertebral anomalies may also occur during the subsequent chondrification stage and are thought to be due to a localized failure of vascularization of the developing cartilaginous centrum. This results in varying degrees of failure of formation of the vertebral body producing a congenital kyphosis or kyphoscoliosis (Tsou 1977; Tsou et al. 1980). In the late chondrification and ossification stages, bony metaplasia may occur in the anterior part of the annulus fibrosus and ring apophysis producing an anterior or anterolateral unsegmented bar which can also result in a congenital kyphosis or kyphoscoliosis (Morin et al. 1985). The ribs form from costal processes, which are small lateral mesenchymal condensations of the developing thoracic somites and contribute cells to all parts of the developing ribs (Christ and Wilting 1992; Evans 2003; Huang et al. 1994, 1996, 2000). The distal tips of the costal processes elongate to form ribs only in the thoracic region of the spine. Rib anomalies probably occur during the process of segmentation and re-segmentation of the developing somites, after which the ribs come to articulate between the definitive thoracic vertebrae. The ribs develop into cartilaginous precursors that ossify during the fetal period. The scapula develops embryologically along with the arm. The arm bud appears in the 3rd week of embryonic life as a small swelling opposite the vertebral segments from the 5th cervical to the 1st thoracic vertebrae. The scapula appears in mesenchyme during the 5th week and gradually migrates caudally. By the end of the 3rd fetal month, the scapula reaches its final anatomical position located lateral to the spine and extending from the 2nd to the 7th or 8th thoracic vertebrae. Occasionally, the scapula may fail to fully descend to its normal location and remains in a permanently elevated position commonly known as Sprengel’s deformity.

4.3  Classification Congenital deformities of the spine are classified by their anatomical location, as well as the pathological anatomy of the vertebral anomaly or anomalies. Congenital vertebral defects causing a scoliosis, kyphosis, or kyphoscoliosis can be mainly due to failures of

47

4  Congenital Deformities of the Spine Congenital scoliosis

a

Failures of formation a

b

c

Failures of segmentation

d

e

f

g

h

Congenital kyphosis and kyphoscoliosis

b a

Failures of segmentation

Failures of formation b

c

d

Mixed anomalies e

f

Fig.  4.1  Classification of congenital scoliosis, kyphosis, and kyphoscoliosis. (A) Congenital scoliosis can be due to either failures of vertebral formation including (a) fully segmented hemivertebra, (b) semi-segmented hemivertebra, (c) incarcerated hemivertebra, (d) unsegmented hemivertebra, (e) wedge vertebra, or failures of vertebral segmentation including (f) unilateral unsegmented bar, (g) unilateral unsegmented bar with contralateral hemivertebra at the same level, (h) block vertebra. (B) Congenital kyphosis can be due to either failures of vertebral formation ((a) posterior hemivertebra) or failures of vertebral segmentation ((d) anterior unsegmented bar). Congenital kyphoscoliosis can be due to either failures of vertebral formation ((b) asymmetrical butterfly vertebra, (c) posterolateral quadrant vertebra), or mixed anomalies ((e, f) anterolateral unsegmented bar with contralateral quadrant vertebra)

vertebral formation or failures of vertebral segmentation (Fig. 4.1). Less commonly, there may be mixed anomalies which are often unclassifiable and difficult to define at birth because at that stage the spine is only 30% ossified. Failures of vertebral formation can be complete or incomplete. Complete failures include different types of hemivertebrae where one half of the vertebral body has failed to form. There are four types of hemivertebra including fully segmented, semi-segmented, unsegmented, and incarcerated. A fully segmented hemivertebra has disc spaces and end plates both above and below, which separate the hemivertebra from the adjacent vertebral bodies. A semi-segmented hemivertebra is congenitally fused to one vertebra cephalad or caudal and separated from the other by a disc space. An unsegmented hemivertebra is

48

4

a

d



A.I. Tsirikos

b

c

e

f

Fig. 4.2  Preoperative radiographs and MRI scans (a–d) of a patient aged 4 years and 7 months with a left posterolateral quadrant vertebra at L2 (black and white arrows on MRI) producing a lumbar kyphoscoliosis. Posteroanterior and lateral radiographs of the spine (e, f) 2.5 years after posterior resection of the hemivertebra followed by segmental stabilization and fusion show normal coronal and sagittal balance of the spine

fused to both the body above and below and has no growth potential. An incarcerated hemivertebra is a small ovoid vertebral segment, which is sitting in a niche formed between the proximal and distal vertebral bodies with limited ability to grow. The presence of a hemivertebra with normal growth plates (fully segmented or semi-segmented) creates an asymmetrical growth of the spine due to the additional growth plates, which are missing on the contralateral side, and results in the development of a scoliosis. Incomplete failures of vertebral formation include a wedge vertebra, which produces asymmetrical growth due to deficient development on the concave side. Varying degrees of failures of vertebral formation can also cause a congenital kyphosis or kyphoscoliosis with the most common type including a posterolateral quadrant vertebra that is due to anterior and unilateral aplasia of one vertebra (Fig.  4.2). A posterior

4  Congenital Deformities of the Spine

49

hemivertebra, which is due to anterior aplasia of the affected vertebra, creates a pure kyphosis, whereas an asymmetrical butterfly vertebra (sagittal cleft vertebra due to anterior and median aplasia) or a wedge vertebra (due to anterolateral hypoplasia) can produce a congenital kyphoscoliosis. Failures of vertebral segmentation include a unilateral unsegmented bar with or without contralateral hemivertebrae at the same level. The bar forms a lateral tether of spinal growth on the concavity of the scoliosis and can extend across two or more vertebral segments. Scoliosis develops due to the combination of growth inhibition by the unsegmented bar, as well as preservation of contralateral growth, which is more accelerated in the presence of one or more hemivertebrae at the same levels. In the presence of bilateral segmentation failure, a block vertebral segment is produced which does not have growth potential and does not carry risk of developing significant deformity. An anterior unsegmented bar can produce a congenital kyphosis with potential for slow progression and little risk for severe deformity. An anterolateral unsegmented bar with or without contralateral hemivertebra at the same level can cause significant growth imbalance and a congenital kyphoscoliosis with high risk of progression. Mixed anomalies can be extensive, affecting large segments and different regions of the spine, and constitute a combination of failures of formation and segmentation; these are commonly associated with rib and chest wall abnormalities tethering the growth of both the spine as well as the thoracic cage. Congenital kyphosis can be also classified according to the alignment of the spinal canal into aligned which can be due to either defects of vertebral formation, segmentation,

Fig.  4.3  Lateral radiographs of the spine showing a congenital kyphosis due to an anterior unsegmented bar (a) and a posterior hemivertebra (b) with a well-aligned spine. Lateral radiograph of the spine on a patient with a congenital kyphosis due to a posterior hemivertebra and a subluxed spine at the T12-L1 level (c)

50

4



A.I. Tsirikos

or mixed anomalies and displaced where there is a step-off deformity with an unstable, subluxed, or dislocated segment above the level of an anomalous hypoplastic vertebra and this results often in a highly progressive deformity with significant risk of neurological complications (Fig. 4.3). Attempts have been made recently to include the posterior element anatomy in the classification systems of congenital spinal deformities by assessing the 3-dimensional images produced by computed tomography scanning (3D CT) (Kawakami et al. 2009; Nakajima et  al. 2007). The posterior vertebral elements may be intact or abnormally formed. This includes bifid areas with open access to the spinal canal or laminae that are partially or fully fused often on the contralateral side between the vertebrae above and below a hemivertebra. A variable preservation or absence of the posterior elements including the pedicles bilaterally can also be noted with failures of vertebral formation. Knowing the detailed anatomy of the posterior vertebral arch is essential when surgical treatment is anticipated. Preoperative CT with 3D reconstruction of the images can provide useful information, assist surgical planning, and reduce the risk of neurological damage.

4.4  Natural History The type, number, and location of congenital vertebral anomalies, as well as their relationship to the adjacent vertebrae will define the natural history of the developing spinal deformity (McMaster and Ohtsuka 1982; McMaster and Singh 1999). Predicting curve progression may be challenging, especially in the presence of mixed/unclassifiable vertebral defects. Deformities which develop due to failures of vertebral formation or segmentation follow a consistent pattern and have a more predictable long-term prognosis. Maximum deterioration of the deformity is expected to occur at the rapid stages of spinal growth during the first 3 years of life and as the patient gets through the adolescent growth spurt (McMaster and Singh 1999). Close monitoring of congenital curves is required as deterioration is often observed even for previously nonprogressive deformities during puberty. For each type of anomaly, the severity of deformity depends on the affected region of the spine. Thoracolumbar curves tend to progress more compared to upper thoracic curves, which have a less severe prognosis (McMaster and Ohtsuka 1982). Identifying those curves that are more likely to progress allows for application of early prophylactic treatment and this in turn can prevent more severe late deformities, as well as the need for complex surgery. The prognosis of a congenital scoliosis due to a fully segmented hemivertebra is often difficult to predict; therefore, surgical treatment is not indicated unless the patient presents with an already severe curve or if there is documented progression of minimum 5° within 6 months of observation. Curve deterioration is generally slow with a mean rate of 1–2°/ year. In the presence of two ipsilateral hemivertebrae, the rate of progression for the congenital scoliosis is expected to increase to 3–4°/year, exceed 50° by age 10 years and reach 70° at skeletal maturity with a greater risk of developing a more severe structural

51

4  Congenital Deformities of the Spine

compensatory curvature at the adjacent levels (Fig. 4.4) (McMaster and Ohtsuka 1982). If two opposing hemivertebrae exist, the prognosis of scoliosis is worse when these affect different regions of the spine. A hemimetameric shift occurs when two opposing hemivertebrae are located in the same region (most commonly thoracic) separated by one or more normal vertebrae (Fig.  4.5) (Shawen et  al. 2002). A hemimetameric shift affecting the ­thoracolumbar or lumbosacral spine is more likely to create an unbalanced deformity and may require surgical treatment. A semi-segmented hemivertebra causes a slowly progressive scoliosis which does not usually exceed 40° at the end of growth and unless located in the lumbosacral spine often it does not need surgery. Fully or semi-segmented hemivertebrae affecting the lumbosacral

a

b

Fig.  4.4  Posteroanterior radiograph of the spine (a) showing two ipsilateral fully segmented hemivertebrae (white arrows) affecting the lumbar spine and lumbosacral junction and causing a congenital scoliosis with a contralateral semi-segmented hemivertebra in the thoracolumbar spine. After posterior resection of the lumbar hemivertebra at age 18  months, the distal scoliosis progressed (b, c) and required revision posterior resection of the lumbosacral hemivertebra (white arrow) followed by instrumented fusion which produced a balanced spine (d)

52

4



c

Fig. 4.4  (continued)

Fig. 4.5  Posteroanterior radiograph of the spine showing two contralateral semi-segmented hemivertebrae affecting the lumbar spine (white arrows) and causing a hemimetameric shift

A.I. Tsirikos

d

4  Congenital Deformities of the Spine

53

junction can create a severe deformity due to an oblique takeoff of the spine, as well as the development of a rapidly progressive structural compensatory scoliosis in the lumbar region as an attempt of the spine to balance. An incarcerated hemivertebra sets out in a niche scalloped out of the adjacent vertebrae, has limited growth potential, and produces minimal deformity which usually does not require treatment. An unsegmented hemivertebra commonly occurs in the thoracic spine, has no ability to grow and does not cause a progressive deformity. The rate of progression of a scoliosis due to a unilateral unsegmented bar depends on the extent of the bar, as well as the presence of normal end plates indicating residual spinal growth on the contralateral side (convexity of the curve). Development of a scoliosis and progression of the curve occurs in the presence of unbalanced vertebral growth. Longitudinal growth of the spine originates from the superior and inferior end plates of every vertebra. Growth potential and, therefore, risk of curve progression can be assessed by evaluating the quality of the disc spaces around the abnormal segments of the spine. The mean rate of scoliosis deterioration due to a unilateral unsegmented bar is 5°/year with the majority of curves exceeding 50° by age 10 years and requiring early surgical treatment. If the unilateral unsegmented bar is associated with contralateral hemivertebra at the same level, the scoliosis has the worst prognosis with a rate of progression which increases to 6°/year with most curves greater than 50° by 2 years of age. A congenital kyphosis or kyphoscoliosis due to a failure of vertebral formation or mixed anomalies (anterolateral bar with contralateral quadrant vertebra) has the least favorable prognosis in terms of rate of progression (McMaster and Singh 1999). Congenital kyphosis and kyphoscoliosis most commonly affect the thoracolumbar spine; however, if the curve extends along the thoracic region the risk of neurological compromise is significantly increased. The severity of kyphosis is proportional to the degree of anterior failure of vertebral formation while in the presence of two adjacent defects of formation the deformity is expected to progress more rapidly. A posterolateral quadrant vertebra produces a kyphoscoliosis which progresses by a mean of 2.5°/year before the age of 10 years and 5°/year during the accelerated pubertal growth, exceeds 80° by age 11 years and carries the highest risk of neurological complications. A kyphoscoliosis due to an asymmetrical butterfly vertebra progresses by 1.5°/year before age 10  years and 4°/year during puberty. An anterior unsegmented bar causes a pure kyphosis which is slowly progressing at a mean rate of 1°/year before 10 years and <2°/year during puberty with no risk of spinal cord compression. An anterolateral unsegmented bar has worse prognosis compared to an anterior bar as it produces a kyphoscoliosis which exceeds 90° at skeletal maturity. A kyphoscoliosis due to an anterolateral bar with contralateral quadrant vertebra has the greatest risk of deterioration at a mean rate of 5°/year before age 10 years and 8°/year during puberty. Spinal cord compression is the most dreaded complication of congenital kyphosis and kyphoscoliosis due to an anterior or anterolateral failure of vertebral formation (posterior hemivertebra or posterolateral quadrant vertebra) at a reported prevalence of 10–12% (Fig. 4.6) (McMaster and Singh 1999; Winter et al. 1973). The onset of symptoms usually occurs during adolescence with variable degree of kyphosis and if left untreated always results in paraplegia.

54

4



A.I. Tsirikos

Fig. 4.6  Sagittal MRI of the spine showing a posterior L1 hemivertebra causing a congenital kyphosis with marked neural compression. The patient presented with developing paraplegia

4.5  Associated Anomalies The development of the spinal column, neural elements, musculoskeletal, cardiovascular, and genitourinary systems occurs during similar embryological stages which results in embryonic insults affecting one or more of these systems. Patients with congenital deformities of the spine, especially those due to mixed vertebral defects can have abnormalities affecting other organ systems at an incidence higher than 61% (Basu et al. 2002; Beals et  al. 1993). These patients present with isolated defects involving different systems or they can be diagnosed with a syndromic condition such as VATER (coexistence of vertebral, anorectal, tracheoesophageal, renal anomalies) or VACTERL (all of the above with the addition of cardiac and limb anomalies).

4.5.1  Intraspinal Abnormalities The neural axis and vertebral column develop during the same stages of embryonic life and, therefore, spinal dysraphism may occur in conjunction with congenital deformities of the spine. Chiari malformation, syringomyelia, tethering of the cord, diastematomyelia,

4  Congenital Deformities of the Spine

55

Fig. 4.7  Posteroanterior radiograph of the spine (a) showing a right T11 incarcerated hemivertebra but no spinal deformity. An MRI scan was obtained and demonstrated a diastematomyelia at the level of the congenital vertebral anomaly (b)

dural bands or cysts, intraspinal lipomas, and a tight filum terminale are the most common dysraphic abnormalities (Fig. 4.7). These occur most commonly in association with a congenital scoliosis due to mixed or vertebral segmentation defects (Basu et al. 2002). The prevalence of intraspinal anomalies has been reported to vary between 18% and 37% with tethered cord being most frequently encountered in patients with a congenital scoliosis (Basu et al. 2002; McMaster 1984; Suh et al. 2001). Patients with congenital spinal deformities and dysraphism may be completely asymptomatic or can present with neurological signs and symptoms varying from subtle asymmetrical leg tendon or abdominal reflexes to severe motor and sensory deficits, bowel and bladder dysfunction, foot deformities, lower limb muscle atrophies or contractures. A thorough neurological examination is required including nerve root tension signs, as well as eliciting abdominal reflexes. The presence of cutaneous lesions such as hairy patches, skin dimples or tags, vascular pigmentation or hemangiomas, increase the possibility of an underlying intraspinal anomaly. An MRI scan to include the whole of the spine should be obtained when congenital vertebral anomalies are identified, especially if surgical treatment is anticipated. The presence of intraspinal abnormalities can affect the rate of deformity progression occasionally more than the associated congenital vertebral defects. Surgical intervention to address underlying intraspinal anomalies may be required before correction of spinal deformity. Surgical correction of spinal deformity can result in severe neurological compromise if the dysraphic pathology is left untreated, especially in the presence of a fixed cord due to distal tethering, diastematomyelia, or herniation of the cerebellar tonsils through the foramen magnum. Previous reports have indicated possible benefits of treating simultaneously the intraspinal lesion and progressive spinal curvature during the same procedure (Hamzaoglu et al. 2007).

56

4



A.I. Tsirikos

4.5.2  Cardiac Congenital cardiac anomalies can occur in 26% of patients with congenital deformities of the spine; ventricular and atrial septal defects are most common (Basu et al. 2002). Other cardiac problems include tetralogy of Fallot and patent ductus arteriosus. A cardiac review with echocardiogram and an ultrasound is recommended as part of initial patient evaluation. Severe cardiac abnormalities, such as Fallot’s tetralogy may require serial operations at different stages of patient’s growth and will have to be addressed before considering correction of spinal deformity.

4.5.3  Genitourinary Patients with congenital scoliosis can have anomalies affecting their kidneys, ureters, and bladder at a prevalence of up to 20%, varying from a unilaterally absent kidney which can be asymptomatic to obstructive uropathy (MacEwen et al. 1972). Up to one-third of these patients may require urological treatment and, therefore, routine screening as part of the initial assessment is advised (Basu et al. 2002). The abnormalities can be identified on an ultrasound or alternatively on the MRI of the spine which includes the abdomen (Drvaric et al. 1987); this often needs to be performed under a short anesthetic in young children.

4.5.4  Musculoskeletal The whole length of the spine should be investigated to exclude Klippel–Feil syndrome with congenital synostosis of cervical vertebrae. Congenital cervical anomalies are particularly associated with a congenital scoliosis affecting the thoracic or lumbar spine (Hensinger et al. 1974). Other abnormalities include radial clubhand, thumb hypoplasia, developmental hip dysplasia, clubfoot, cavus foot, vertical talus, as well as limb length deficiencies or limb atrophies. The ribs are formed in close association with the vertebrae and it is, therefore, not surprising to have a combination of developmental abnormalities affecting both the ribs and vertebrae (Christ and Wilting 1992; Evans 2003; Huang et al. 1994, 1996, 2000). Rib and chest wall defects have been noted in 19.2% of the patients with congenital spinal deformities followed in our spinal unit (Tsirikos and McMaster 2005). These developmental chest wall abnormalities may be simple (79%) or complex (21%) and are due to either a failure of segmentation or ­formation of the ribs (Fig. 4.8). Most common simple rib anomaly is a localized fusion of two or three consecutive ribs; most common complex abnormality involves a combination of fused ribs with a large adjacent thoracic wall defect. Congenital rib anomalies occur usually on the concavity of a thoracic or thoracolumbar congenital scoliosis due to a unilateral failure of vertebral segmentation (Tsirikos and McMaster 2005). A likely explanation for the close association between the side of rib

4  Congenital Deformities of the Spine

57

Fig. 4.8  Plain radiographs showing simple ((a) fused ribs next to a small unilateral unsegmented bar) and complex ((b) multiple fused ribs and adjacent chest wall defects next to a long unilateral unsegmented bar) rib anomalies in conjunction with a congenital scoliosis

abnormalities and this type of congenital scoliosis is a localized unilateral embryological error resulting in a failure of segmentation of both the primitive ribs and vertebrae on the same side occurring during the same developmental stage. These rib abnormalities do not appear to have an adverse effect on curve size or rate of deformity progression which is determined primarily by the vertebral segmentation defect causing severe unilateral imbalance in the longitudinal growth of the spine. The main driving force for the development of the scoliosis in these patients is the unilateral failure of vertebral segmentation, and this greatly exceeds any adverse effect from the rib fusions (Tsirikos and McMaster 2005). An extensive thoracic congenital scoliosis associated with fused ribs may affect thoracic function and growth of the lungs in young children and lead to thoracic insufficiency syndrome. An imbalance in the mechanical thrust of the ribs may also adversely affect spinal growth, as well as the function of trunk muscles and pressure within the thorax (Piggott 1971; Roaf 1960; Shahcheraghi and Hobbi 1999). Rib and chest wall abnormalities are less frequently encountered in patients with a ­congenital lumbar or lumbosacral scoliosis, a kyphoscoliosis or a pure congenital kyphosis. Sprengel’s shoulder can also occur in patients with congenital deformities of the spine at a prevalence of 7% and is mostly associated with a cervicothoracic or thoracic scoliosis due to a unilateral failure of vertebral segmentation (Tsirikos and McMaster 2005). The combination of a congenital high scapula lying on the convexity of an upper thoracic congenital scoliosis causes a significant deformity due to elevation of the shoulder line and often impairment of shoulder function (Fig. 4.9). These deformities usually require surgical treatment both for the scoliosis and also a distal displacement of the scapula in relation

58

4



A.I. Tsirikos

Fig. 4.9  Preoperative (a) and postoperative (b) radiographs of a patient with left Sprengel’s shoulder treated surgically with excellent outcome (Woodward procedure)

to the vertebral column. In contrast, when the Sprengel’s deformity is on the concavity of the scoliosis, it often partially compensates for the cosmetic deformity caused by the elevation of the contralateral shoulder on the convexity of the curve. This minimizes shoulder asymmetry and usually does not require reduction of the congenitally elevated scapula.

4.6  Imaging Plain radiographs of the spine will allow recognition of the nature of congenital vertebral anomalies and classification of the deformity. A lateral radiograph should always be obtained to exclude an associated kyphotic deformity which carries the highest risk for neurological complications. The radiographs can be taken with the patient in the erect position apart from infants before their walking stage where these can be obtained supine

4  Congenital Deformities of the Spine

59

Fig. 4.10  Posteroanterior radiograph of the spine (a) and CT scans (b) with 3D reconstruction (c) showing a right lumbosacral semi-segmented hemivertebra (white arrows) producing a scoliosis. This was resected through a posterior approach to the spine followed by segmental stabilization and fusion with excellent outcome (d)

or sitting. As the patient moves developmentally from the supine to the sitting position, an apparent progression of the curve may be observed and does not necessarily signify true deterioration of the deformity. The posteroanterior and lateral spinal radiographs will determine the type of vertebral abnormality, measure the size of the curvature, and assess growth potential around the area of the vertebral defect. Curve progression can be documented using consistent anatomical landmarks on serial radiographs; however, the intraobserver and interobserver error of Cobb measurement may fluctuate between 3 and 12° (Facanha-Filho et al. 2001; Loder et al. 1995). Defining growth potential of the vertebral anomaly provides an indication on the risk of deformity deterioration until skeletal maturity. A fully segmented hemivertebra with normal disc spaces and end plates both above and below can be used as an example of increased risk for scoliosis progression compared to a semi-segmented or incarcerated hemivertebra and this can usually be recognized on plain radiographs. The prognosis of a unilateral unsegmented bar to a large extent depends on the presence of wide, normal-appearing disc spaces on the contralateral side which indicate normal end plates and an increased deforming force. CT scans can provide more detailed information on the anatomical nature of the vertebral abnormalities including identification of posterior element defects (Fig.  4.10). Threedimensional reconstruction of the images has become an integral part of surgical planning in order to produce a “surgical map” which can assist decision-making and intervention design (Bush and Kalen 1999; Newton et al. 2002). An MRI of the spine should be performed in every patient who requires surgical treatment in order to exclude intraspinal anomalies.

60

4



A.I. Tsirikos

4.7  Treatment 4.7.1  Observation Close monitoring of patients who present with congenital deformities of the spine is needed with the aim to identify progression of congenital, as well as structural compensatory curvatures at an early stage and apply prophylactic treatment. The type of vertebral defect and spinal curve will define prognosis; the principle of management is to treat the patients early and prevent the development of severe deformities which then require complex surgery with increased risk of ­complications and prolonged associated morbidity. The patients should be followed up to skeletal maturity ­usually at 6–12-month intervals with more close observation during periods of rapid growth at the first 3 years of life, as well as during puberty. Some formation (unsegmented or incarcerated hemivertebra) and segmentation (block vertebra) anomalies can be predictably expected to remain fairly stable or change by only a few degrees at follow-up and these are unlikely to require surgical treatment. In contrast, unilateral failures of segmentation (unilateral unsegmented bar with or without contralateral hemivertebra at the same level) or fully segmented hemivertebrae have significant deforming potential and usually necessitate early surgery.

4.7.2  Bracing Brace treatment is not effective to address congenital curves which are usually inflexible. Moreover, attempts to apply corrective forces through rigid braces in young children with fixed curvatures can cause or exacerbate chest wall deformities (Winter et  al. 1976). Bracing may be effecting to control or slow down progression of structural compensatory curves developing at the levels either proximal or distal to a congenital scoliosis.

4.7.3  Surgical Surgical correction is indicated when there is documented curve progression or prophylactically in the presence of vertebral anomalies which carry a bad prognosis for causing severe deformity and/or neurological complications (for example, scoliosis due to a unilateral failure of vertebral segmentation, kyphosis or kyphoscoliosis due to a failure of vertebral formation). Age is not necessarily a limiting factor to consider surgical correction for patients with deformities which are expected to progress rapidly. Spinal imbalance and trunk shift in relation to the type and location of deformity should also be taken into account during decision-making on surgical treatment. Congenital scoliosis affecting the cervicothoracic region causes a significant deformity due to shoulder

4  Congenital Deformities of the Spine

61

asymmetry, as well as neck tilt and is likely to require stabilization. Congenital scoliosis located in the lumbosacral junction is equally deforming as it produces an oblique takeoff of the spine often with marked pelvic obliquity and the consequent development of a large structural compensatory lumbar curve. In this case, surgical correction of the congenital curvature is indicated at an early stage of growth and before the structural compensatory lumbar scoliosis develops. The aim of surgery is to produce a balanced spine with stable thoracic cage, delay spinal fusion in order to preserve as much spinal growth as possible, and limit vertebral segments included in the fusion in order to maintain spinal flexibility. Associated dysraphic lesions, such as tethered cord, diastematomyelia and Chiari I malformation, usually require treatment before deformity correction is considered. The use of intraoperative spinal cord monitoring during surgery to address the intraspinal pathology or the deformity is imperative due to the high risk of neurological complications and should record ideally both somatosensory and motor-evoked potentials. Surgical options include in situ fusion with bone graft, convex hemiepiphysiodesis (growth arrest procedure) using bone graft, deformity correction through segmental vertebral resection and fusion, deformity correction by posterior spinal fusion using instrumentation associated with releases and facetectomies, deformity correction through spinal osteotomies followed by fusion, and growth preservation techniques (growing rodsVEPTR). Often more than one surgical technique is required on the same patient to address deformities at different levels of the spine.

4.7.3.1  In Situ Spinal Fusion This is best indicated in young patients with congenital scoliosis due to a unilateral unsegmented bar with or without contralateral hemivertebra at the same level. With the use of bone graft the aim of the procedure is to stabilize but not correct the deformity; therefore, it should be performed as soon as there is documented progression and while the curvature is still small as prophylactic treatment. Complete facetectomies and posterior element decortications should be performed followed by bone grafting to achieve a solid fusion. Autologous rib graft harvested through the same incision and supplemented by allograft bone can be used. The arthrodesis should include one level above and below the levels of the abnormalities followed by application of a spinal plaster jacket for 3–4  months. A spinal cast cannot be used for cervicothoracic or upper thoracic curves. The addition of an anterior arthrodesis can produce a bony fusion and eliminate the risk of crankshaft effect which may be observed in congenital scoliosis due to continued anterior vertebral growth in the presence of a solid posterior fusion (Terek et  al. 1991). Congenital thoracic scoliosis due to a segmentation defect can be treated effectively through an isolated anterior convex fusion with the use of an autologous rib strut extending one level above and below the vertebral abnormality without the need for a posterior in situ fusion. Increased blood loss should be expected in young children with a small body weight during preparation of the vertebral bodies to place the rib strut graft.

62

4



A.I. Tsirikos

The recent advent of small-size pediatric instrumentation can provide a more stable fixation, reduce the risk of nonunion and bending of the fusion mass which has been reported in 14% of patients (Winter et al. 1984), and allow for a small degree of correction across the levels above and below the segmentation anomaly. In the presence of a failure of vertebral segmentation which limits the longitudinal growth of the spine, an early fusion does not have an adverse effect on the patient’s predicted height and development. A localized posterior in situ arthrodesis with bone graft is also indicated for patients younger than 5 years with a congenital kyphosis up to 50° with the aim to produce a posterior spinal tether and this should extend at least one level above and below the most

a

b

Fig. 4.11  Lateral radiograph of the spine (a) showing a posterior hemivertebra at L1 producing a congenital kyphosis with a subluxed spine and step-off deformity. At age 1  year the patient underwent a localized in situ posterior spinal arthrodesis with bone graft followed by application of a supportive spinal jacket for 3 months. After surgery, the kyphosis further progressed (b, c) and a revision posterior arthrodesis was required to repair a non-union at the apex of deformity. Two years after revision surgery the localized kyphosis is spontaneously improving due to remaining anterior vertebral growth (d)

63

4  Congenital Deformities of the Spine

c

d

Fig. 4.11  (continued)

sagittally tilted vertebra. Preserving residual anterior vertebral growth in the presence of a solid posterior fusion would allow some degree of spontaneous correction of the kyphosis during the remaining stages of growth, but this is difficult to predict. The risk of nonunion following initial surgery is high due to mechanical disadvantage of the bone graft which is under tension. Placement of a spinal plaster jacket is indicated for a period of 3–4 months. Exploration of the fusion mass to repair a pseudarthrosis or augment the fusion should be performed if progression of the deformity >5° is observed in the first few months after removal of the cast (Fig. 4.11).

4.7.3.2  Convex Growth Arrest Procedure (Hemiepiphysiodesis) This is performed traditionally through a combined anterior and posterior approach to the spine at the convex side of the curvature. It is indicated in young children with a short congenital scoliosis due to a unilateral failure of vertebral formation (for example, a fully segmented hemivertebra) located ideally in the thoracic spine (Andrew and Piggott 1985).

64

4



A.I. Tsirikos

The convex half of the disc and adjacent end plates are removed at the level of the hemivertebra, as well as across one segment above and below. The posterior hemiepiphysiodesis extends across the same levels and the concave side is not exposed. The procedure eliminates the deforming force on the convex side and is expected to allow for gradual spontaneous improvement of the curve over time due to the presence of contralateral vertebral growth, but the final outcome in terms of amount of remaining deformity is unpredictable and no correction at follow-up has occasionally been observed (Thompson et al. 1995). A  hemiepiphysiodesis performed in the presence of a contralateral failure of vertebral ­segmentation, such as a unilateral bar which prevents concave growth, acts as an in situ fusion and is not expected to improve the size of the curve.

a

d

b

c

e

Fig.  4.12  Posteroanterior and lateral radiographs (a, b) of the spine and coronal MRI scan (c)  showing a left L3 posterolateral quadrant vertebra (white arrows) producing a congenital kyphoscoliosis. The patient was treated with a left convex anterior growth arrest procedure which controlled the scoliosis but resulted in a localized lumbar kyphosis (d, e)

4  Congenital Deformities of the Spine

65

An isolated anterior convex growth arrest procedure using an autologous rib strut graft harvested during the thoracotomy is often equally successful to the combined procedure in order to control scoliotic curves located in the thoracic region. This has a localized kyphogenic effect due to the presence of normal remaining posterior growth and is less effective when performed for congenital scoliosis affecting the lumbar spine (Fig.  4.12). In this case, the convex hemiepiphysiodesis can be best performed through a combined anterior and posterior approach to the spine.

4.7.3.3  Hemivertebra Resection This is indicated in patients with a progressive congenital scoliosis, kyphoscoliosis, or kyphosis due to a lateral, posterolateral, or posterior fully or semi-segmented hemivertebra. The benefit of the procedure is that it removes the abnormal vertebral segment and eliminates the deforming force across the spine. It also provides a better ability to balance the spine and can be performed even for severe curves where a localized in situ fusion or a convex hemiepiphysiodesis would be unable to produce good trunk alignment. The procedure is technically challenging and should be performed by surgeons with a high level of experience due to the increased risk of neurological complications (Holte et al. 1995). Excision of a lateral or posterolateral hemivertebra can be performed through either a combined sequential anteroposterior (Klemme et al. 2001) or an isolated posterior approach to the spine (Ruf and Harms 2002; Ruf et al. 2009). Simultaneous anterior and posterior exposure to the spine can also be done with the patient in the lateral position which allows resection of the hemivertebra and adjacent discs followed by placement of posterior compressive instrumentation and correction of the curve (Lazar and Hall 1999). An anterior hemivertebra resection should be expected to increase significantly the amount of blood loss compared to the posterior-only procedure. The isolated posterior procedure includes initial removal of the abnormal posterior elements followed by hemivertebra excision in a piecemeal manner through the pedicle. The lateral wall of the hemivertebra is removed through a subperiosteal exposure to protect the segmental and major vessels anteriorly. The discs above and below the hemivertebra are excised and the contralateral disc on the opposite side to the hemivertebra is released to allow for compression of the remaining convex gap with the use of instrumentation. Spinal instrumentation is superior to casting in order to achieve and maintain deformity correction (Figs.  4.2, 4.4 and 4.10). Despite the ability to stabilize the spine using small-size modern instrumentation, postoperative support through a plaster jacket is advised for 3–4  months after hemivertebra excision. Wedge resection of a posterior hemivertebra causing a pure congenital kyphosis is best done through a posterior approach to the spine which provides better access to the anomalous vertebra compared to the anterior approach followed by segmental stabilization and fusion. Hemivertebra resection should be ideally performed in children around the age of 2 years when the anatomy is easier to identify as the vertebrae are more ossified, a fusion can be achieved more predictably and transpedicular instrumentation can be used. The procedure is safer when the hemivertebra is located below the level of the spinal cord

66

4

a

d



A.I. Tsirikos

b

c

e

Fig.  4.13  Posteroanterior radiograph of the spine (a) on an infant aged 10  months showing a congenital left thoracolumbar scoliosis due to a semi-segmented hemivertebra at T13, as well as a right upper thoracic scoliosis due to a left unilateral unsegmented bar with contralateral hemivertebra at the same level (white arrows). Both curves progressed rapidly (b) and the patient underwent at age 15 months a posterior resection of the thoracolumbar hemivertebra followed by instrumented segmental arthrodesis (c, d), as well as a posterior in situ fusion of the upper thoracic spine. Following surgery he was fitted with an underarm spinal brace in order to control the remaining scoliosis above and below the thoracolumbar junction (e)

where the neural elements are more amenable to manipulation. The ideal indication for hemivertebra excision is a lumbosacral hemivertebra due to increased risk of producing a very severe deformity (Fig. 4.10). However, not infrequently the sacrum may be deficient with a wide spina bifida and this can make application of instrumentation very challenging. Hemivertebra resection can also be performed safely in the thoracic spine (Deviren et al. 2001; Ruf and Harms 2002; Ruf et al. 2009).

4  Congenital Deformities of the Spine

67

Congenital scoliosis or kyphoscoliosis due to a hemivertebra may occasionally involve a longer segment of the spine and in that case the instrumented fusion after hemivertebra excision may have to extend across more levels; alternatively the patient may need postoperative bracing as an additional measure in order to preserve growth, control adjacent deformity and delay extension of the fusion for a later stage of growth (Fig. 4.13).

4.7.3.4  Instrumented Correction and Fusion This is indicated for older patients with stiff congenital deformities where balancing of the spine with partial curve correction can be achieved through the mobile segments above and below the anomalous vertebrae. The use of pedicle screw/hook or all-pedicle screw instrumentation allows some degree of deformity correction, as well as a solid spinal fixation which will enhance fusion (Fig. 4.14). Due to the presence of posterior element defects across the levels of the congenitally abnormal vertebrae the application of instrumentation can be challenging. In the presence of a sharply angular congenital kyphosis the posterior implants may also become prominent under the skin, especially in young and slim patients. Distraction forces on the concavity of the curvature should be avoided as much as preoperative skeletal traction due to the increased neurological risk, particularly in patients with a kyphotic deformity. The addition of anterior release can address the risk of crankshaft phenomenon in immature patients, can increase curve flexibility mainly across the normal vertebral segments included in the deformity and can also provide the additional cosmetic benefit of the anterior thoracoplasty. An anterior arthrodesis using a vascularized or free rib strut autograft can provide support to the spine and achieve fusion if posterior instrumentation cannot be used, particularly in the presence of severe congenital kyphosis. This should be followed by postoperative casting for 3–4 months to increase stability until fusion of the rib graft has been achieved.

4.7.3.5  Spinal Reconstruction Using Osteotomies and Vertebral Column Resection Complex spinal reconstruction can be performed through multi-segment osteotomies or vertebral column resection followed by instrumented arthrodesis. This is reserved for very severe rigid and neglected deformities which produce a highly unbalanced spine with marked decompensation, listing of the trunk, fixed pelvic obliquity, associated neurological compromise, and which cannot be managed successfully by the procedures discussed so far in this chapter. Such extreme deformities may require resection of part of the vertebral column and this can be performed through either a posterior-only or an anteroposterior approach to the spine depending on the type and location of congenital vertebral anomalies. A posterior approach is particularly indicated in patients with significant congenital kyphosis or kyphoscoliosis with or without neurological complications in whom the apex of the deformity is sitting against the spinal canal and can be accessed and excised easier posteriorly.

68

4

a



A.I. Tsirikos

b

c

d

e

f

Fig. 4.14  Posteroanterior and lateral radiographs of the spine (a, b), as well as MRI scans (c, d) showing two asymmetrical butterfly vertebrae (white arrows) causing a congenital kyphoscoliosis. The patient underwent a posterior spinal arthrodesis combined with posterior releases to mobilize the deformity and allow for correction. A well-balanced spine in both coronal and sagittal planes was achieved (e, f)

The posterior-only subperiosteal resection has also the advantage of preserving the segmental spinal vessels which may be abnormal especially around the levels of the vertebral abnormalities, thus, reducing the neurological risk compared to an anteroposterior resection where the convex vessels have to be sacrificed. In general, vertebral column resection results in shortening of the spinal column and, therefore, does not carry the additional risk of neurological injury due to distraction forces applied to the cord. Spinal osteotomies through previous fusion masses may be required in patients who undergo revision surgery to address residual or recurrent congenital deformities. Osteotomy

4  Congenital Deformities of the Spine

69

of a unilateral unsegmented bar can be performed at the apex of the curve often in association with a contralateral hemivertebra resection through a posterior approach to the spine, in order to achieve acute correction of a severe deformity followed by instrumented arthrodesis. The fundamental of treatment of congenital deformities of the spine is to allow for early recognition of those types of vertebral anomalies and curvatures which carry predictably an unfavorable prognosis in terms of relentless progression and this would make more simple prophylactic treatment effective in controlling the pathology.

4.7.3.6  Growth Preservation Techniques Trunk height and often chest wall development is reduced in children with complex congenital deformities compared to those with normal spines and this is directly proportional to the number and extent of vertebral abnormalities. Avoiding early spinal fusion has the advantage of preventing further stunting of spinal growth. Instrumentation without fusion in the form of growing rods has been extensively used in the management of early onset scoliosis. Growing rods can also be applied in patients with congenital scoliosis in order to prevent deformity progression, maximize growth of the spine, and delay definitive fusion for as long as this is possible (Klemme et al. 1997). Their role in the treatment of congenital scoliosis remains controversial; however, a possible indication would be in children with a unilateral defect of segmentation (unsegmented bar with or without contralateral hemivertebra) in conjunction with a limited anterior convex arthrodesis in order to control the curve above and below the levels of the fusion (Fig.  4.15). Equally, in children with a long congenital scoliosis due to a hemivertebra treated through a convex hemiepiphysiodesis as an adjunct to prevent deterioration of the curvature across the segments cephalad and caudal to the hemivertebra as an alternative to bracing. Placement of the growing rods involves very limited subperiosteal exposure of the spine only at the proximal and distal anchors to insert hooks and/or screws along with segmental bone grafting in order to secure the points of fixation. The rods run subfacial and are linked either through end-to-end or lateral domino connectors. Unilateral or bilateral growing rod constructs can be used. Complications of growing rods include rod breakage, hook dislodgement, and screw pull-out occurring most commonly with unilateral constructs, as well as gradual stiffening of the spine resulting in a limited ability to lengthen over time which happens earlier if a bilateral construct has been used. Every lengthening procedure which is indicated at 6-month intervals has a kyphogenic effect with the development of proximal junctional kyphosis being one of the most severe and difficult to correct complications of growing rods. Supportive bracing may reduce the risk of implant failure while the growing rods are in place. The vertical expandable prosthetic titanium rib (VEPTR) devices have been developed to address severe congenital rib and chest wall deformities leading to thoracic insufficiency syndrome. These thoracic wall anomalies can occur in isolation along with segmentation defects of the vertebrae or as part of a syndromic condition, such as spondylocostal dysostosis or spondylothoracic dysplasia. Campbell et al. (2003) suggested that extensive

70



A.I. Tsirikos

4

Fig. 4.15  Posteroanterior radiograph of the spine (a) showing a congenital left thoracic scoliosis due to the presence of a left-T6 fully segmented hemivertebra (white arrow) with contralateral unsegmented bar between T5 and T7. The patient underwent an anterior convex hemiepiphysiodesis including convex disc excision and the use of a rib strut graft (b, c) followed by placement of a concave growing rod in order to control the remaining of the spine. Four years later the spine is stable and his scoliosis is well maintained with consecutive rod lengthenings (d)

rib fusions affecting the hemithorax on the concavity of a congenital scoliosis in growing children can act as a powerful lateral tether to further unbalance the development of the spine, which is already being deformed by asymmetrical vertebral growth. In addition, an extensive thoracic congenital scoliosis may affect chest function and growth of the lungs in young children and result in severe respiratory impairment. In order to overcome the problem of a congenital scoliosis associated with chest wall anomalies producing thoracic insufficiency, Campbell and Hell-Vocke (2003) developed the surgical technique of expansion thoracoplasty, in which the concave hemithorax is lengthened and stabilized by serial rib distractions using the VEPTR. The VEPTR includes a ribto-rib and a rib-to-spine device secured at the anchor points with the use of hooks. The rods can be lengthened every 4–6 months through interconnectors in a similar way to the growing rod construct. The complications of the VEPTR procedure include rod breakage, hook dislodgement, rib fractures, as well as spontaneous rib fusions. The adverse effect of the expansion thoracotomy and subsequent scarring on an already compromised chest has not been clarified. Consensus has not been reached on the role of the VEPTR device to address a primary congenital scoliosis in patients who do not have associated rib fusions or thoracic insufficiency.

4  Congenital Deformities of the Spine

71

References Andrew, T., Piggott, H.: Growth arrest for progressive scoliosis: combined anterior and posterior fusion of the convexity. J. Bone Joint Surg. Br. 67, 193–197 (1985) Basu, P.S., Elsebaie, H., Noordeen, M.H.: Congenital spinal deformity: a comprehensive assessment at presentation. Spine 27, 2255–2259 (2002) Beals, R.K., Robbins, J.R., Rolfe, B.: Anomalies associated with vertebral malformations. Spine 18, 1329–1332 (1993) Bush, C.H., Kalen, V.: Three dimensional computed tomography in the assessment of congenital scoliosis. Skeletal Radiol. 28, 632–637 (1999) Campbell Jr., R.M., Hell-Vocke, A.K.: Growth of the thoracic spine in congenital scoliosis after expansion thoracoplasty. J. Bone Joint Surg. Am. 85, 409–420 (2003) Campbell Jr., R.M., Smith, M.D., Mayes, T.C., et al.: The characteristics of thoracic insufficiency syndrome associated with fused ribs and congenital scoliosis. J. Bone Joint Surg. Am. 85, 399–408 (2003) Christ, B., Wilting, J.: From somites to vertebral column. Ann. Anat. 174, 23–32 (1992) Deviren, V., Berven, S., Smith, J.A., et  al.: Excision of hemivertebrae in the management of ­congenital scoliosis involving the thoracic and thoracolumbar spine. J. Bone Joint Surg. Br. 83, 496–500 (2001) Drvaric, D.M., Ruderman, R.J., Conrad, R.W., et al.: Congenital scoliosis and urinary tract abnormalities: are intravenous pyelograms necessary? J. Pediatr. Orthop. 7, 441–443 (1987) Evans, D.J.R.: Contribution of somitic cells to the avian ribs. Dev. Biol. 256, 114–126 (2003) Facanha-Filho, F.A., Winter, R.B., Lonstein, J.E., et al.: Measurement accuracy in congenital scoliosis. J. Bone Joint Surg. Am. 83, 42–45 (2001) Hamzaoglu, A., Ozturk, C., Tezer, M., et al.: Simultaneous surgical treatment in congenital scoliosis and/or kyphosis associated with intraspinal abnormalities. Spine 32, 2880–2884 (2007) Hensinger, R.N., Lang, J.E., MacEwen, G.D.: Klippel-Feil syndrome: a constellation of associated anomalies. J. Bone Joint Surg. Am. 56, 1246–1253 (1974) Holte, D.C., Winter, R.B., Lonstein, J.E., et al.: Excision of hemivertebrae and wedge resection in the treatment of congenital scoliosis. J. Bone Joint Surg. Am. 77, 159–171 (1995) Huang, R., Zhi, Q., Wilting, J., et al.: The fate of the somito-coele cells in avian embryos. Anat. Embryol. 190, 243–250 (1994) Huang, R., Zhi, Q., Neubuser, A., et al.: Function of somite and somitocoele cells in the formation of the vertebral motion segment in avian embryos. Acta Anat. 155, 231–241 (1996) Huang, R., Zhi, Q., Scmhidt, C., et al.: Sclerotomal origin of the ribs. Development 127, 527–532 (2000) Kawakami, N., Tsuji, T., Imagama, S., et al.: Classification of congenital scoliosis and kyphosis: a new approach to the three-dimensional classification for progressive vertebral anomalies requiring operative treatment. Spine 34, 1756–1765 (2009) Klemme, W.R., Denis, F., Winter, R.B., et al.: Spinal instrumentation without fusion for progressive scoliosis in young children. J. Pediatr. Orthop. 17, 734–742 (1997) Klemme, W.R., Polly Jr., D.W., Orchowski, J.R.: Hemivertebral excision for congenital scoliosis in very young children. J. Pediatr. Orthop. 21, 761–764 (2001) Lazar, R.D., Hall, J.E.: Simultaneous anterior and posterior hemiovertebra excision. Clin. Orthop. 364, 76–84 (1999) Loder, R.T., Urquhart, A., Steen, H., et al.: Variability in Cobb angle measurements in children with congenital scoliosis. J. Bone Joint Surg. Br. 77, 768–770 (1995) MacEwen, G.D., Winter, R.B., Hardy, J.H.: Evaluation of kidney anomalies in congenital scoliosis. J. Bone Joint Surg. Am. 54, 1451–1454 (1972) McMaster, M.J.: Occult intraspinal anomalies and congenital scoliosis. J. Bone Joint Surg. Am. 66, 588–601 (1984)

72

4



A.I. Tsirikos

McMaster, M.J., Ohtsuka, K.: The natural history of congenital scoliosis: a study of 251 patients. J. Bone Joint Surg. Am. 64, 1128–1147 (1982) McMaster, M.J., Singh, H.: Natural history of congenital kyphosis and kyphoscoliosis: a study of 112 patients. J. Bone Joint Surg. Am. 81, 1367–1383 (1999) Morin, B., Poitras, B., Duhaime, M., et al.: Congenital kyphosis by segmentation defect: etiologic and pathogenic studies. J. Pediatr. Orthop. 5, 309–314 (1985) Nakajima, A., Kawakami, N., Imagama, S., et al.: Three-dimensional analysis of formation failure in congenital scoliosis. Spine 32, 562–567 (2007) Newton, P.O., Hahn, G.W., Fricka, K.B., et al.: Utility of three-dimensional and multiplanar reformatted computed tomography for evaluation of pediatric congenital spine abnormalities. Spine 27, 844–850 (2002) Piggott, H.: Posterior rib resection in scoliosis. A preliminary report. J. Bone Joint Surg. Br. 53, 663–671 (1971) Roaf, R.: Vertebral growth and its mechanical control. J. Bone Joint Surg. Br. 42, 40–59 (1960) Ruf, M., Harms, J.: Hemivertebra resection by a posterior approach: innovative operative technique and first results. Spine 27, 1116–1123 (2002) Ruf, M., Jensen, R., Letko, L., et al.: Hemivertebra resection and osteotomies in congenital spine deformity. Spine 34, 1791–1799 (2009) Shahcheraghi, G.H., Hobbi, M.H.: Patterns and progression in congenital scoliosis. J. Pediatr. Orthop. 19, 766–775 (1999) Shawen, S.B., Belmont Jr., P.J., Kuklo, T.R., et al.: Hemimetameric segmental shift: a case series and review. Spine 27, E539–E544 (2002) Suh, S.W., Sarwark, J.F., Vora, A., et al.: Evaluating congenital spine deformities for intraspinal anomalies with magnetic resonance imaging. J. Pediatr. Orthop. 21, 525–531 (2001) Terek, R.M., Wehner, J., Lubicky, J.P.: Crankshaft phenomenon in congenital scoliosis: a preliminary report. J. Pediatr. Orthop. 11, 527–532 (1991) Thompson, A.G., Marks, D.S., Sayampanathan, S.R., et al.: Long-term results of combined anterior and posterior convex epiphysiodesis for congenital scoliosis due to hemivertebrae. Spine 20, 1380–1385 (1995) Tsirikos, A.I., McMaster, M.J.: Congenital anomalies of the ribs and chest wall associated with congenital deformities of the spine. J. Bone Joint Surg. Am. 87, 2523–2536 (2005) Tsou, P.M.: Embryology of congenital kyphosis. Clin. Orthop. Relat. Res. 128, 18–25 (1977) Tsou, P.M., Yau, A., Hodgson, A.R.: Embryogenesis and prenatal development of congenital vertebral anomalies and their classification. Clin. Orthop. Relat. Res. 152, 211–231 (1980) Winter, R.B., Moe, J.H., Eilers, V.E.: Congenital scoliosis. A study of 234 patients treated and untreated. J. Bone Joint Surg. Am. 50, 1–15 (1968) Winter, R.B., Moe, J.H., Wang, J.K.: Congenital kyphosis. Its natural history and treatment as observed in a study of 130 patients. J. Bone Joint Surg. Am. 55, 223–256 (1973) Winter, R.B., Moe, J.H., MacEwen, G.D., et  al.: The Milwaukee brace in the nonoperative ­treatment of congenital scoliosis. Spine 1, 85–96 (1976) Winter, R.B., Moe, J.H., Lonstein, J.E.: Posterior spinal arthrodesis for congenital scoliosis: an analysis of the cases of two hundred and ninety patients, five to nineteen years old. J. Bone Joint Surg. Am. 66, 1188–1197 (1984)

Neuromuscular Spine Deformities

5

Carol-Claudius Hasler

5.1  General Considerations As opposed to idiopathic scoliosis, patients with neuromuscular scoliosis are physically impaired and functionally disabled. This includes a restriction or lack of ability to perform normal activities. Any therapeutic strategy should aim at prevention of future decline (symptoms, function, death), improvement of the current state (symptoms, pain, respiratory, and physical disability) under consideration of external factors in the disablement process such as behavioural, lifestyle, psychological, medication, external supports, rehabilitation, and social and physical environment. Impaired motor control of spinal muscles due to neuromuscular diseases with spasticity or hypotonia may lead to scoliosis in up to 90% of patients. The probability of its development inversely correlates with ambulatory abilities; very high rates of scoliosis in nonambulators with poor head control (Madigan and Wallace 1981). Associated negative predictors are osteopenia and concomitant congenital malformations which cause rapid progression (collapsing spine). The onset of spinal deformities depends on the evolution, the extent, and the severity of the functional component and the involvement of trunk muscles. The natural history of the specific underlying neuromuscular pathology dictates the risk of progression and determines therapeutic strategy, particularly the ideal time point for a surgical intervention. In contrast to idiopathic spine deformities which usually evolve in otherwise healthy individuals, neuromuscular patients bear other medical issues (crooked spine in a sick patient) that largely influence the risk profile. Growth is just one of these many issues. Accordingly, deformities already developed in childhood to a level where treatment – usually a “buy time” strategy until definitive fusion – is warranted. The pubertal growth spurt stiffens the initially flexible curve which shows a more postural character at the beginning.

C.-C. Hasler Orthopaedic Department, University Children’s Hospital, Spitalstrasse 33, 4056 Basel, Switzerland e-mail: [email protected] M. Yazici (ed.), Non-Idiopathic Spine Deformities in Young Children, DOI: 10.1007/978-3-642-19417-7_5, © 2011 EFORT

73

74

5



C.-C. Hasler

This pathologic multisystem complex persists through adolescence into adulthood as a lifelong challenge. It involves a variable compound of poor nutrition, soft-tissue conditions, soft bone, pulmonary infections, urogenital infection, cardiac problems, previous spine surgery, caregivers, orthotic management, social workers, family, and the patient with his or her highly individual needs. Mental retardation may or may not be part of a neuromuscular condition. In non-CP patients it is often not or only to a lesser degree an issue. Spine-wise, coronal decompensation is the biggest issue. Hyperkyphosis further decreases the patient’s interaction and verbal communication. The basic therapeutic goals are above all a re-balancing of the spine to provide trunk stability, maintain sitting, standing, or walking ability. Hence, a solid base is built for the individual, allowing optimal motor and cognitive development. Seating adjustments and wheelchair modifications have a supportive role but do not provide an isolated long-term solution. Bracing advocated as the primary therapeutic mainstay has generally no impact on the progression rate. It is often challenging or impossible from the start in those mostly underweight patients and bears the risk of pressure sores and skin ulcerations. In addition, it may negatively interfere with respiratory function or gastrointestinal issues like feeding tubes. Serial casting is an alternative but requires repetitive anesthesia, is in most places a lost art, and bears the same shortcomings as the brace. As a consequence, curve progression inflicts on the spine surgeon the decision between an operative growth-sparing buy-time procedure until spinal fusion or a primary definitive instrumented fusion. Therapeutic strategy and timing of surgery heavily depend on the natural history of the disease process. In strong contradiction to idiopathic scoliosis coronal Cobb angle and residual growth are not the most prominent parameters of the decision-making process. Particularly the cumulating risks for repeat anesthesia and surgery of growth-sparing techniques should be weighed out against the shortcoming of early spinal fusion (Hasler et al. 2010). Weight-bearing growing implants for the lifetime of their use are susceptible to loosening, failure, skin sloughs, and wound infections and the disadvantages of repeat hospitalization (germs, psychological trauma, indirect costs to family and caregivers, allergies to adhesives, missing school, etc.). A strategy with repetitive surgery comprises an average of four to five interventions, two complications, one unplanned surgery per patient and a 25% chance of wound complications. The risks and complications are directly related to the severity of the neurological impairment. Infection is the main risk and correlates to poor nutrition, delicate soft-tissues, and wound tension. Somatosensory-evoked potential (SSEP) and motor-evoked potential (MEP) monitoring during spinal intervention for children with substantial (standing transfer) motor function preoperatively are mandatory. It is highly recommended to include the upper extremities as shoulder–arm and hand function is crucial for independence of wheelchairbound individuals. This applies to all types of intervention since arm positioning may harm the plexus but is specifically recommended for placement of VEPTR rib cradles. Fixation to the first rib and excessive lengthening has to be avoided to prevent cranial migration of the upper fixation. In conclusion, operative interventions should be restricted to specialized centers where an interdisciplinary approach is routine and high-standard perioperative management including respiratory care, prevention of pressure sores, and orthosis-free quick mobilization is provided. Numerous issues specific to certain diseases are highlighted in the following sections.

5  Neuromuscular Spine Deformities

75

References Hasler, C.C., Mehrkens, A., Hefti, F.: Efficacy and safety of VEPTR instrumentation for progressive spine deformities in young children without rib fusions. Eur. Spine J. 19(3), 400–408 (2010) Madigan, R.R., Wallace, S.L.: Scoliosis in the institutionalized cerebral palsy population. Spine (Phila 1976) 6(6), 583–590 (1981)

 

Cerebral Palsy

6

Freeman Miller

The most common cause of scoliosis in children with cerebral palsy is spinal collapse, which is due to spasticity in quadriplegic pattern cerebral palsy. Children who have hypotonia have a lower risk of scoliosis, but they may develop spinal deformities often with significant kyphosis. Individuals with severe extensor posturing may develop total spinal lordosis. Children with movement disorder such as athetosis or dystonia have a lower incidence of scoliosis than those with spasticity. The incidence of scoliosis in institutionalized individuals, most of whom were spastic quadriplegic pattern, has been reported at 64% with a strong inverse relationship to ambulatory ability (Madigan and Wallace 1981). Individuals who are dependent sitters with no head control may have an incidence as high as 90% (Madigan and Wallace 1981). The natural history of spinal deformity in children with cerebral palsy is to develop scoliosis in middle late childhood (6–10 years old), usually as very flexible postural curves with the child tending to lean always toward one side. Typically, as the child goes into early adolescent growth, the spine develops a structural scoliosis with a rotational component. Subsequently, as the child grows faster and puberty develops the scoliosis magnitude may progress with maximum progress occurring when the curve is in the 40–60° range. Maximum curve progression of 4° a month has been seen in our clinic, although 2° a month is more typical (Miller et al. 1996). As the upright sitting scoliosis reaches 80–100° it rapidly develops increasing stiffness. This structural curve typically becomes so stiff that physical correction even when the child is lying is impossible. The spinal stiffness typically increases as the child develops hormonal maturity and as the curve magnitude increases toward the end of growth. The time for surgical intervention is before the spinal stiffness develops usually with a sitting scoliosis less then 80°. Children with cerebral palsy due to known anoxic cause seldom develop a ­significant scoliosis in early and middle childhood. The scoliosis does frequently develop as a flexible scoliosis in middle childhood but it can be easily managed with seating support or propsitting flexible thoracolumbar orthosis. There are a few children, less than 1%, usually with a diagnosis cerebral palsy because no other diagnosis can be assigned, who develop early

F. Miller AI duPont Hospital for Children, Wilmington, DE 19807, USA e-mail: [email protected] M. Yazici (ed.), Non-Idiopathic Spine Deformities in Young Children, DOI: 10.1007/978-3-642-19417-7_6, © 2011 EFORT

77

78

6



F. Miller

childhood scoliosis often at age 3 or 4. These curves tend to develop early and progressive stiffness, and by age 5 or 6 they have a 60–80° stiff scoliosis (Fig. 6.1). These children need early surgical management and are too young for a total spinal fusion. Localized fusion of the curve apex has been my preference with extension of the fusion at

a

b

Fig. 6.1  This 5-year-old girl with cerebral palsy quadriplegic pattern presented with parent complaints of increasing scoliosis and pelvic obliquity making seating difficult. The supine radiograph demonstrated pelvic obliquity with elevated left pelvis caused by a severe left spastic hip subluxation. (a) The hip was repaired and the child was stable with seating adaptations until age 12 when the pelvic obliquity and scoliosis again increased. (b) Continued seating adaptations were able to keep her comfortable in the wheel chair until age 14 when she had rapid progression during her accelerated adolescent growth. (c) Her curve was then instrumented with a unit rod and by age 15; 1 year postoperative she has excellent sitting ability, no pelvic obliquity, and an excellent fusion mass. (d) This is the most common pattern of presentation and treatment of cerebral palsy scoliosis

79

6  Cerebral Palsy

c

d

Fig. 6.1  (continued)

adolescence when the curve adds on and the deformity again progresses. This works well if the curve is a localized short sharp curve, but does not work well if it is a long total spinal curve where a subcutaneous growing rod works better.

6.1  Nonoperative Management The nonoperative management of the neurologic spinal deformity in individuals with spasticity or other motor control issues is directed at providing the child improved sitting or postural stability to maximize motor and cognitive function (Letts et  al. 1992; Shoham

80

6



F. Miller

et al. 2004). When the use of orthotics is compared against the natural history of spinal deformities of similar patients without orthotic management, the orthosis does not seem to have any impact on the rate of scoliosis progression or on the eventual magnitude of the scoliosis curve (Miller et al. 1996). Because the goal of these orthoses should be to provide comfortable postural support, the orthotic used should be a soft material used in the fashion of a corset (Letts et al. 1992). Since this postural support is used for the benefit of sitting, there is no indication to the use these orthoses during nighttime or times when the child is lying. Since many of these children also have respiratory restrictions or gastrointestinal motility problems, care has to be taken that this orthotic use does not further impair either a gastrointestinal or respiratory function. Another excellent option for the conservative management of the scoliosis in its flexible stage is to use offset chest laterals to help prop the child up with modular seating adjustments in the wheelchair. This has the advantage that it is relatively simple for the family to use. However, it has the disadvantage that adjustments for seasonal clothing wear are more difficult. Other modalities of treatment such as therapeutic stretching or therapeutic positioning, electrical stimulation or botulinum toxin injection have not documented any impact on the natural history of the deformity.

6.2  Surgical Indications The spinal deformity should be monitored clinically by physical examination for both the magnitude and flexibility of the curve. As a definite structural curve is identified, routine x-rays usually, every 6 months, should be made on a standardized sitting frame. As the spinal deformity increases toward 60–90° in magnitude on the sitting spine x-ray, the stiffness of the deformity by physical examination also increases. This combination of increasing curve magnitude to approximately 60° with increasing stiffness is an indication to proceed to spinal instrumentation even if significant growth is remaining. Using these indications, the youngest age for surgery is 8 or 9 years and the mean age is 12 years. As long as the scoliosis maintains substantial flexibility on the physical examination, posterior fusion alone can be performed typically up to approximately 90° of deformity. For those curves with more than 90° of scoliosis or with severe stiffness, anterior release over the apex of the curve is indicated. This requirement for doing an anterior release will increase the complication rate of the procedure (Dias et al. 1996; Hopf and Eysel 2000; Tsirikos et al. 2003a; Westerlund et al. 2001); however, it is necessary to gain flexibility to be able to do the posterior correction. It is not clear at this time whether it is safer to perform this as a staged release on the same day or if it should be staged on different days, approximately a week apart. One report notes approximately the same incidence of complications (Ferguson et  al. 1996). However, another report suggests there were slightly fewer complications if the procedure was staged (Tsirikos et al. 2003a). Our current practice is to stage those patients who have very severe cerebral palsy with multiple medical complications and problems. However, we tend to do patients who are relatively

6  Cerebral Palsy

81

healthy in one stage. There is no indication to do an anterior fusion to prevent crankshaft deformity in children with open triradiate cartilages if the unit rod instrumentation is used for the fusion. Scoliosis greater than 40 or 50° is indicated for spinal fusion in patients with neurologic control problems who have completed growth. It is felt that a spinal deformity of this magnitude has a very high likelihood of continuing to progress. However, minor curves, especially those less than 30° have less likelihood of progression, although the scientific evidence based on long-term follow-ups to support this approach is not very good. Individuals with motor control problems also develop a pathologic kyphosis and lordosis. The indications for surgical treatment of these deformities are much less clear. In some patients, the kyphosis may be due to very tight hamstrings and can be improved by lengthening of the hamstrings to prevent the pelvis from tilting posteriorly and enforcing a kyphotic sitting posture. However, as children get older and larger, these same adaptations no longer work well. As the adolescent become heavier they develop more problems with the ability to lift up the head to look forward. In patients with functional vision it is reasonable to consider spinal instrumentation for increasing collapsing kyphosis to improve their sitting posture and to allow them to interact more with their environment (Lipton et al. 2003). There are also individuals who develop rather severe lordosis often but not always associated with scoliosis. This lordosis may be totally asymptomatic and cause few problems until it suddenly becomes painful. Often when the pain starts, it is impossible to do any seating adaptations or make any other changes to improve the pain. In these individuals, a spinal instrumentation is indicated and is the only treatment that alleviates the pain from sitting (Lipton et al. 2003). Over 50% of the individuals who develop a painful lordosis have had a posterior dorsal rhizotomy as a younger child.

6.3  Surgical Indications Based on the Child as a Whole There are a number of children with very severe neurologic disability with no head control and severe mental retardation in whom sometimes the benefits and risks of the surgical procedure may be difficult to weigh. If families have decided to provide only comfort care and not aggressive medical care for these individuals, they may elect not to treat the spinal deformity. However, if a family is intent upon providing the child maximal medical treatment with the goal of having them stay in the home to be able to take them out into the community, then a spinal instrumentation is the procedure which will provide the child and the family ease and comfort to provide this care. The risks and complications associated with this large operation are directly related to the severity of the neurologic impairment. Specifically, a child who is unable to orally feed, who is severely mentally retarded, who cannot speak, and who cannot sit independently has by far the highest complication rate (Lipton et al. 1999). Prior to surgery, children should have maximum medical management of their seizures, gastroesophageal reflux, and gastric motility. The nutritional level of these children may be very hard to assess and it is very difficult to use any specific

82

6



F. Miller

p­ reoperative nutritional values. We find that a child who is over weight from gastrostomy tube feeding is at higher risk than the child who is under weight. Except for those children in extremely severe stages of malnutrition, we found no nutritional markers to be related to complications (Lipton et al. 1999).

6.4  The Surgical Procedure The proper preparation for the surgical procedure should require intra-arterial monitoring of blood pressure, good vascular access usually using a large central venous catheter plus several peripheral lines. Blood loss in children with cerebral palsy is unpredictable, but there is a tendency for more bleeding even when the prothrombin time (PT) or the partial thromboplastin time (PTT) are completely normal (Kannan et al. 2002). The preoperative preparation should anticipate large blood loss to prevent one of the most severe complications of this procedure, which is having to alter or abort the operative procedure because of blood loss prior to completion of the procedure. Intraoperative use of amicar may reduce bleeding (Thompson et al. 2008). Intraoperative and postoperative antibiotics should be used both intravenous and in the bone graft (Borkhuu et al. 2008). Our preferred instrumentation is the unit rod that was specifically developed to treat neuromuscular scoliosis (Dias et  al. 1996; Tsirikos et  al. 2008). This rod comes precontoured with the goal of instrumentation from the pelvis to T-1. It includes a normal lordosis and kyphosis profile. After implanting the rod into the pelvis, there is a long lever arm to correct pelvic obliquity, scoliosis, and kyphosis. Intraoperative spinal cord monitoring using somatosensory-evoked potentials (SSEPs) or motor-evoked potentials (MEPs) should be utilized in individuals with neuromuscular deformities if the individuals have substantial motor function to preserve. This specifically means monitoring is indicated for individuals who can do standing transfers or who can ambulate. For those individuals who have no ability to stand or ambulate, the ability to do adequate SSEP and MEP monitoring is greatly reduced (DiCindio et al. 2003). Furthermore, in this group of individuals with severe motor impairment, all intraoperative attempts should be made to provide safety with the instrumentation and prevent neurologic injury. However, in the event of neurologic insult it is very difficult to justify not proceeding with the surgical procedure, correction of deformity, and implantation of the instrumentation. In individuals who have ambulatory ability or the ability to do weight bearing, there is technically more ability to do SSEP and MEP monitoring and the functional risk/benefit ratio is higher (DiCindio et al. 2003). In these individuals, one might consider removing instrumentation or not instrumenting a curve, based on neurologic changes obtained during monitoring. However, the risk/benefit ratio of leaving the operating room without doing the planned procedure in any specific individual has to always be considered. Another consideration is to understand that the appropriate treatment of a paralyzed child with a severe spinal deformity is a spine instrumentation and fusion; therefore, a surgeon should always weigh carefully the risk/benefit ratio to the child of aborting a surgical procedure before the original goal is accomplished.

6  Cerebral Palsy

83

6.5  Postoperative Management Because many of these children have multiple system involvement, they should usually be managed in an intensive care unit with pediatric intensive care specialists available. The intensive care management should continue with careful monitoring of the blood pressure and maintaining urinary output at a level of half to 1 cc/kg/h. Hemoglobin should be maintained above 9 g for the first 48 h because rapid fluid shifts may cause the hemoglobin to drop and the child to become hypotensive. Prophylactic antibiotics are typically used for 24 h. Careful respiratory management is extremely important with the child often needing to be intubated overnight or for several days if they have very poor respiratory function. Aggressive postoperative nutrition is important, especially in those individuals who have very little reserve. The child should seldom go more than 3 or 4 days without being fed. Often this requires intravenous central hyperalimentation, typically started on postoperative day 2 or 3. By placing a jejunostomy tube preoperative, early postoperative enteral feeding can also be started. There continues to be controversy around enteral feeding in the face of rising amylase and lipase levels, especially if this is presumed to be subclinical pancreatitis (He et al. 2004). This is a relatively common problem when lipase and amylase are monitored, which we do routinely because of the high rate of pancreatitis. After the acute recovery, the child needs to be mobilized out of bed quickly into a wheelchair. There is no need to use any external support such as an orthoses. Range of motion of the upper and lower extremities should be started early. The child’s personal wheelchair should be carefully readjusted as there is a very high likelihood of developing pressure sores if the child is forced back into the same wheelchair they were in with their severe spinal deformity. Typically, children can return to school without restrictions in 3–4 weeks after the surgery (Tsirikos et al. 2008).

6.6  Complications Because this is a large operative procedure performed on individuals who often have multisystem compromise, one has to be very careful to manage complications in other systems. The most common problems occur in the pulmonary system ranging from minor annoyance such as atelectasis to severe problems requiring prolonged ventilatory support. Children who require long-term intensive care for their respiratory problems have the poorest long-term survival (Tsirikos et al. 2003b). The next most common set of complications are related to the GI system with pancreatitis, prolonged ilius, superior mesenteric artery syndrome, gall bladder disease, and poor gastric motility, all being relatively common. There is clearly an increased incidence of pancreatitis compared to children with idiopathic scoliosis and this may be related to an ischemic reperfusion syndrome (He et al. 2004). Seizures seldom cause significant problems when they are managed with adequate antileptics.

84

6



F. Miller

The most common surgical complication is a wound infection and deep wound infections occur in approximately 3–5% of fusions in children with cerebral palsy (Sponseller et al. 2000; Szoke et al. 1998). Although most of these deep wound infections can be managed with wound debridement and allowing the wound to heal by secondary intention (Szoke et al. 1998), some individuals with deep wound infections do require hardware removal but this seems to be much more common in patients with myelomeningocele than in cerebral palsy (Sponseller et al. 2000). Correction of the spinal deformity with the unit rod allows correction of approximately 75–80% of the scoliosis and pelvic obliquity with excellent alignment of the sagittal plane (Dias et al. 1996; Tsirikos et al. 2008). With children with a substantial amount of growth remaining, recurrent crankshaft deformities are a significant concern; however, with unit rod instrumentation with only posterior spinal fusion, sufficient stability is obtained to prevent any long-term recurrent spinal deformity or crankshafting (Smucker and Miller 2001; Westerlund et al. 2001). Patients who are fused with significant growth remaining continue to have chest wall growth. As the chest wall grows laterally it also seems to grow distally; this combined with proximal growth of the ileac crest means that the ribs may overlap the pelvis. Although this is a common finding in children fused early in their adolescent growth, I have not ever identified any problem associated with this. For individuals who are ambulatory and develop a neurologic type of scoliosis which extends down into the lumbar spine, correction may require a fusion to the pelvis. Fusion to the pelvis does not alter the ambulatory ability in children with cerebral palsy if the sagittal plane, lordosis, and kyphosis are maintained, as is done with the unit rod instrumentation (Tsirikos et al. 2003c). The sagittal plane balance can be very well maintained using the unit rod instrumentation; however, lordotic deformities have higher mechanical complication rates because of the difficulty of implanting the unit rod with this deformity (Tsirikos et al. 2008). There are also substantial problems with sagittal plane deformity when individual rods are used and then cross-connected, especially with backing out at the pelvis, and if the instrumentation does not extend at least to T-1 or T-2, proximal fall-off in kyphotic deformities often occurs.

6.7  Outcome The outcome of spinal instrumentation for individuals with motor control problems demonstrates a consistently very high satisfaction rate among parents and caretakers (Jones et  al. 2003; Tsirikos et  al. 2004). It is somewhat more difficult to determine functional benefits in the individual patients. In a group of children, which included those with the most severe neurologic involvement with spinal deformity, there is a predicted 70% survival at 11 years following surgery (Tsirikos et al. 2003b). Except for very severe scoliosis and prolonged postoperative intensive care requirements for pulmonary issues, there were no other correlations to poor survival.

6  Cerebral Palsy

85

6.8  Summary In summary, spinal deformity is common in children with spastic quadriplegic ­pattern cerebral palsy. The vast majority of the children who develop spinal deformities do require surgical stabilization if their goal is good long-term sitting ability. This instrumentation can be performed with an acceptable rate of complications with the unit rod instrumentation being the current preferred instrumentation method for this group of children. Very high caretaker satisfaction can be expected at the conclusion of this procedure.

References Borkhuu, B., Borowski, A., Shah, S.A., Littleton, A.G., Dabney, K.W., Miller, F.: Antibioticloaded allograft decreases the rate of acute deep wound infection after spinal fusion in cerebral palsy. Spine 33(21), 2300–2304 (2008) Dias, R.C., Miller, F., Dabney, K., Lipton, G., Temple, T.: Surgical correction of spinal deformity using a unit rod in children with cerebral palsy. J. Pediatr. Orthop. 16(6), 734–740 (1996) DiCindio, S., Theroux, M., Shah, S., Miller, F., Dabney, K., Brislin, R.P., Schwartz, D.: Multi­ modality monitoring of transcranial electric motor and somatosensory-evoked potentials during surgical correction of spinal deformity in patients with cerebral palsy and other neuromuscular disorders. Spine 28(16), 1851–1855 (2003); discussion 1855–1856 Ferguson, R.L., Hansen, M.M., Nicholas, D.A., Allen Jr., B.L.: Same-day versus staged anteriorposterior spinal surgery in a neuromuscular scoliosis population: the evaluation of medical complications. J. Pediatr. Orthop. 16(3), 293–303 (1996) He, Z., Tonb, D.J., Dabney, K.W., Miller, F., Shah, S.A., Brenn, B.R., Theroux, M.C., Mehta, D.I.: Cytokine release, pancreatic injury, and risk of acute pancreatitis after spinal fusion surgery. Dig. Dis. Sci. 49(1), 143–149 (2004) Hopf, C.G., Eysel, P.: One-stage versus two-stage spinal fusion in neuromuscular scoliosis. J. Pediatr. Orthop. B 9(4), 234–243 (2000) Jones, K.B., Sponseller, P.D., Shindle, M.K., McCarthy, M.L.: Longitudinal parental perceptions of spinal fusion for neuromuscular spine deformity in patients with totally involved cerebral palsy. J. Pediatr. Orthop. 23(2), 143–149 (2003) Kannan, S., Meert, K.L., Mooney, J.F., Hillman-Wiseman, C., Warrier, I.: Bleeding and coagulation changes during spinal fusion surgery: a comparison of neuromuscular and idiopathic scoliosis patients. Pediatr. Crit. Care Med. 3(4), 364–369 (2002) Letts, M., Rathbone, D., Yamashita, T., Nichol, B., Keeler, A.: Soft Boston orthosis in management of neuromuscular scoliosis: a preliminary report. J. Pediatr. Orthop. 12(4), 470–474 (1992) Lipton, G.E., Miller, F., Dabney, K.W., Altiok, H., Bachrach, S.J.: Factors predicting postoperative complications following spinal fusions in children with cerebral palsy. J. Spinal Disord. 12(3), 197–205 (1999) Lipton, G.E., Letonoff, E.J., Dabney, K.W., Miller, F., McCarthy, H.C.: Correction of sagittal plane spinal deformities with unit rod instrumentation in children with cerebral palsy. J. Bone Joint Surg. Am. 85-A(12), 2349–2357 (2003)

86

6



F. Miller

Madigan, R.R., Wallace, S.L.: Scoliosis in the institutionalized cerebral palsy population. Spine 6(6), 583–590 (1981) Miller, A., Temple, T., Miller, F.: Impact of orthoses on the rate of scoliosis progression in children with cerebral palsy. J. Pediatr. Orthop. 16(3), 332–335 (1996) Shoham, Y., Meyer, S., Katz-Leurer, M., Tamar Weiss, P.L.: The influence of seat adjustment and a thoraco-lumbar-sacral orthosis on the distribution of body-seat pressure in children with scoliosis and pelvic obliquity. Disabil. Rehabil. 26(1), 21–26 (2004) Smucker, J.D., Miller, F.: Crankshaft effect after posterior spinal fusion and unit rod instrumentation in children with cerebral palsy. J. Pediatr. Orthop. 21(1), 108–112 (2001) Sponseller, P.D., LaPorte, D.M., Hungerford, M.W., Eck, K., Bridwell, K.H., Lenke, L.G.: Deep wound infections after neuromuscular scoliosis surgery: a multicenter study of risk factors and treatment outcomes. Spine 25(19), 2461–2466 (2000) Szoke, G., Lipton, G., Miller, F., Dabney, K.: Wound infection after spinal fusion in children with cerebral palsy. J. Pediatr. Orthop. 18(6), 727–733 (1998) Thompson, G.H., Florentino-Pineda, I., Poe-Kochert, C., Armstrong, D.G., Son-Hing, J.: Role of Amicar in surgery for neuromuscular scoliosis. Spine 33(24), 2623–2629 (2008) Tsirikos, A.I., Chang, W.N., Dabney, K.W., Miller, F.: Comparison of one-stage versus two-stage anteroposterior spinal fusion in pediatric patients with cerebral palsy and neuromuscular scoliosis. Spine 28(12), 1300–1305 (2003a) Tsirikos, A.I., Chang, W.N., Dabney, K.W., Miller, F., Glutting, J.: Life expectancy in pediatric patients with cerebral palsy and neuromuscular scoliosis who underwent spinal fusion. Dev. Med. Child Neurol. 45(10), 677–682 (2003b) Tsirikos, A.I., Chang, W.N., Shah, S.A., Dabney, K.W., Miller, F.: Preserving ambulatory potential in pediatric patients with cerebral palsy who undergo spinal fusion using unit rod instrumentation. Spine 28(5), 480–483 (2003c) Tsirikos, A.I., Chang, W.N., Dabney, K.W., Miller, F.: Comparison of parents’ and caregivers’ satisfaction after spinal fusion in children with cerebral palsy. J. Pediatr. Orthop. 24(1), 54–58 (2004) Tsirikos, A.I., Lipton, G., Chang, W.N., Dabney, K.W., Miller, F.: Surgical correction of scoliosis in pediatric patients with cerebral palsy using the unit rod instrumentation. Spine 33(10), ­1133–1140 (2008) Westerlund, L.E., Gill, S.S., Jarosz, T.S., Abel, M.F., Blanco, J.S.: Posterior-only unit rod instrumentation and fusion for neuromuscular scoliosis. Spine 26(18), 1984–1989 (2001)

Duchenne’s Muscular Dystrophy and Spinal Muscular Atrophy

7

Dietrich Schlenzka

Duchenne’s Muscular Dystrophy is a hereditary progressive muscle disease. It is linked to the x-chromosome. Its inheritance is recessive. The gene defect causes a disturbance in the synthesis of the muscle protein Dystrophin. This leads to a degradation of the skeletal musculature followed by lipomatosis and fibrosis. The clinical picture is characterized by progressive muscle weakness. In the early phase, a pseudohypertrophy of the musculature due to lipomatosis is visible. Walking difficulties are often detected already at an age of 1–3 years. The walking ability is lost usually at an age of around 10 years. Pulmonary function declines rapidly after loss of walking ability. The life expectancy is shortened. The majority of the patients die between 14 and 25  years of age from respiratory problems or due to cardiomyopathy. The final diagnosis is made by a blood test showing increased levels of Creatinkinase. For determination of subtypes of muscle diseases, muscle biopsy is used. Prenatal diagnosis is possible by modern DNA tests. The general treatment consists in prevention of joint contractures and providing of a wheelchair and appliances to ease activities of daily living. In the later stadium, respiratory support becomes necessary. Progressive spinal deformity is common in Duchenne’s. The incidence of scoliosis varies in different reports from 48% to 93% (Forst 2000); 60% of the patients develop a scoliosis within 3 years after becoming wheelchair dependent (Hart and McDonald 1998). Kinali et al. (2006) analyzed 123 patients at an age of at least 17 years in a 10-year retrospective follow-up; 10% of the patients did not have scoliosis, 13% had mild nonprogressive curves, and another 13% had moderate curves (up to 50°) managed conservatively. Oda et  al. (1993) defined three different curve types: Type I, progressive collapsing kyphoscoliosis with significant rotation; Type II, progressive hyperlordotic curve; and Type III, in the sagittal profile straight spines with nonprogressive curves under 30°. Predictors for curve progression in the individual case have not been described. Pelvic obliquity is common in curves over 40–50°. There is a strong correlation between decline of percent FVC, age, and degree of scoliosis (Kurz et al. 1983).

D. Schlenzka ORTON Orthopaedic Hospital, Invalid Foundation, Tenholantie 10, FIN-00280 Helsinki, Finland e-mail: [email protected] M. Yazici (ed.), Non-Idiopathic Spine Deformities in Young Children, DOI: 10.1007/978-3-642-19417-7_7, © 2011 EFORT

87

88

7



D. Schlenzka

Brace treatment is questionable in this condition. It could not be shown that bracing can slow curve progression. On the other hand, the brace interferes with pulmonary function. To date, early surgery is generally accepted as treatment of choice. Operation is recommended for curves of 40–50° Cobb angle. In recent years, a strong trend toward earlier operation is visible. This allows for maximum curve correction resulting in normal spinal alignment in the coronal as well as the sagittal plane. Improved spinal alignment enhances sitting balance and comfort. So far, however, it could not be shown that better curve correction leads to an overall improved patient outcome (Kinali et al. 2006). The data on the effect of spine surgery on respiratory function and life expectancy are conflicting. Kurz et al. (1983) reported a slower rate of decline of respiratory function after spinal fusion. They recommend surgery. Galasko et  al. (1992) compared operated and non-operated patients and found an improved survival rate in patients who had undergone spinal stabilization. Kennedy et al. (1995) stated that spinal surgery does not alter the decline of pulmonary function, nor does it improve survival. According to a Cochran review by Cheuk et al. (2007), based on the data available, no evidence-based recommendation can be made concerning surgery for scoliosis in Duchenne’s. Spinal Muscular Atrophy is a hereditary muscle disease affecting 1 out of 15,000 life births. It is caused by a defect in the Survival Motor Neuron gene (SMN1) and leads to the degeneration of the lower motor neuron. The consequence is progressive muscle atrophy. Three types of the disease with different course and degree of severity have been described: Type I: Acute infantile (Werdnig–Hoffmann) It becomes evident at birth or during the first months of life by muscle weakness and impaired breathing. Most children die within the first 2 years. Type II: Chronic infantile (Werdnig–Hoffmann) It starts at an age between 6 and 18 months. The lower extremities are more affected than the upper. The children are often able to sit. Some learn to stand or to walk with support. If the onset of symptoms is after the age of 18 months the life expectancy may be normal. Type III: Juvenile (Kugelberg–Welander) It has its onset between the age of 2 and 10 years. Initially, the children learn to stand and walk normally. First symptoms are proximal paresis and muscle atrophy starting at the lower extremities. Progression of symptoms is usually very slow. Life expectancy may be normal. The incidence of scoliosis in the infantile type of spinal muscular atrophy is 78–100%. Curve development starts usually during the first decade of life. The majority of curves progress to a mean Cobb angle of 90° (range 20–164). Curves are usually collapsing, sometimes kyphotic. Severe pelvic obliquity is common (Hart and McDonald 1998). As in Duchenne’s, brace treatment is not capable of preventing curve progression. It is used sometimes to improve sitting balance and function if surgery is not considered or impossible.

7  Duchenne’s Muscular Dystrophy and Spinal Muscular Atrophy 

89

Generally accepted indication for surgery is 40 to 50 Cobb angle. To minimize the risk of complications and to achieve perfect alignment with lesser risk for the patient, many surgeons prefer to perform the operation already at lower Cobb angles. Decline in functional activities after spine surgery has been reported by some authors (Hart and McDonald 1998). Fusion is not recommended in ambulatory patients.

7.1  Surgery in Duchenne’s and Spinal Muscular Atrophy The aims of surgery are:

• To prevent curve progression • To improve spinopelvic alignment and spinal balance in the coronal as well as in the sagittal plane

• To slow deterioration of respiratory function • To improve quality of life • To increase life expectancy There are no data available defining how much correction is necessary or how much residual deformity can be accepted without jeopardizing the patient’s outcome. Decision-making and preoperative workup are teamwork. Cardiac, pulmonary, and nutritional status has to be evaluated. A respiratory function of less than 60% means an increased risk of complications. We avoid surgery if the vital capacity is less than 30% of the normal. Usually, only the posterior approach is possible due to impaired pulmonary function. The value of preoperative traction is unclear. In Duchenne’s, the risk of high intraoperative blood loss has also to be encountered. Duchenne’s patients have a significantly prolonged bleeding time but normal platelet function (Turturro et al. 2005). Segmental spinal fixation (wires, hooks, screws) is mandatory to achieve sufficient stability of the construct for brace-free postoperative mobilization of the patient. It is advisable to fuse long in every case. Instrumentation and fusion should always be carried out from the upper thoracic spine down to L5 to avoid the development of a secondary deformity above or below (Fig. 7.1). There are different opinions among spine surgeons concerning the indication for fusion to the sacrum/pelvis. Several authors found fusion to L5 sufficient for most cases (Mubarak et al. 1993; Sengupta et al. 2002; Sussman et al. 1996). Other authors present figures from 10° to 30° of pelvic obliquity as threshold values for decision-making toward pelvic fixation (Forst 2000; Ouellet and Arlet 2007; Widman et al. 1999). However, no scientific data on the relation between pelvic obliquity and patient outcome or quality of life are available.

90

7



D. Schlenzka

a

b

Fig. 7.1  Preoperative (a) and 3-year follow-up radiograph (b) of a 17-year-old male with Duchenne’s muscular dystrophy. Posterior Luque fixation and fusion was performed from T4 to L5

It is the author’s practice to stop the fusion at L5 if the curve is fully or almost fully correctable, regardless of the preoperative pelvic obliquity. In these cases, usually, pelvic obliquity improves secondarily to curve correction (Fig. 7.2). Fixation to the sacropelvis is performed by the author in severe stiff curves not sufficiently correctible by posterior surgery only if pelvic obliquity exceeds largely 30° (Fig. 7.3). The classic pelvic fixation is achieved by introducing the properly configurated proximal ends of Luque rods bilaterally between the outer and the inner table of the posterior iliac wing (Luque–Galvestone technique) (Allen and Ferguson 1984). A frequently seen complication of this technique is the painful loosening of the rods in the ileum (windshield wiper phenomenon). A more developed technique combining iliac screws and iliosacral screws (“MW-fixation”) provides enhanced stability as pelvic

7  Duchenne’s Muscular Dystrophy and Spinal Muscular Atrophy 

91

structures are often hypoplastic and bone quality is usually very poor in these patients (Arlet et al. 1999). The use of bank bone (fresh frozen allograft) for fusion has proven to be safe and very effective based on more than 20 years of experience at the author’s institution. The role of bone substitutes is not clear yet. Complications are common in this kind of extensive surgery in patients with poor general condition (Cervelatti et al. 2004; Ferguson et al. 1996). Respiratory and cardiac failure, massive intraoperative blood loss, instrumentation problems and loss of correction, infection, and death have been described. This underlines the need for thorough multidisciplinary preoperative evaluation, responsible decision-making, high-level surgical resources, and experience.

a

b

Fig. 7.2  Preoperative (a, b) and 1-year follow-up radiographs (c, d) of a 15-year-old male with Duchenne’s muscular dystrophy. Posterior hybrid fixation was performed from T5 to L5. Note improvement of sagittal profile, pelvic obliquity, and spinal balance

92

7



D. Schlenzka

c

Fig. 7.2  (continued)

d

7  Duchenne’s Muscular Dystrophy and Spinal Muscular Atrophy 

a

c

93

b

d

Fig 7.3  A 26-year-old female with spinal muscular atrophy. After hybrid instrumentation from T2 to the pelvis, thoracolumbar curve improved from 130° to 65°, pelvic obliquity from 50° to 22° (a, c), and thoracolumbar kyphosis from 100° to 70° (b, d). Photographs show considerable improvement in patient’s posture (e–h). Spinal osteotomy to achieve better alignment was not ­possible to perform due to poor respiratory function

94

7



D. Schlenzka

e

f

g

h

Fig. 7.3  (continued)

7  Duchenne’s Muscular Dystrophy and Spinal Muscular Atrophy 

95

References Allen, B.L., Ferguson, R.L.: The Galveston technique of pelvic fixation with L-rod instrumentation of the spine. Spine 9, 388–394 (1984) Arlet, V., Marchesi, D., Papin, P., et al.: The ‘MW’ sacropelvic construct: an enhanced fixation of the lumbosacral junction in neuromuscular pelvic obliquity. Eur. Spine J. 8, 229–231 (1999) Cervelatti, S., Bettini, N., Moscato, M., et al.: Surgical treatment of spinal deformities in Duchenne muscular dystrophy: a long term follow-up study. Eur. Spine J. 13, 441–448 (2004) Cheuk, D.K., Wong, V., Wraige, E., et al.: Surgery for scoliosis in Duchenne muscular dystrophy. Cochrane Database Syst. Rev. (1), CD005375 (2007) Ferguson, R.L., Hansen, M.M., Nicholas, D.A., et al.: Same-day versus staged anterior-posterior spinal surgery in a neuromuscular scoliosis population: the evaluation of medical complications. J. Pediatr. Orthop. 16, 293–303 (1996) Forst, R.: Die orthopädische Behandlung der Duchenne-Muskeldystrophie, p. 55. Enke im Thieme Verlag, Stuttgart/New York (2000) Galasko, C.S.B., Delaney, C., Morris, P.: Spinal stabilisation in Duchenne muscular dystrophy. J. Bone Joint Surg. Br. 74-B, 210–214 (1992) Hart, D., McDonald, C.: Spinal deformity in progressive neuromuscular disease. Phys. Med. Rehabil. Clin. N. Am. 9, 213–232 (1998) Kennedy, J.D., Staples, A.J., Brook, P.D., et  al.: Effect of spinal surgery on lung function in Duchenne muscular dystrophy. Thorax 50, 1173–1178 (1995) Kinali, M., Messina, S., Mercury, E., et al.: Management of scoliosis in Duchenne muscular dystrophy: a large ten-year retrospective study. Dev. Med. Child Neurol. 48, 513–518 (2006) Kurz, L.T., Mubarak, S.J., Schultz, P., et al.: Correlation of scoliosis and pulmonary function in Duchenne muscular dystrophy. J. Pediatr. Orthop. 3, 347–353 (1983) Mubarak, S.J., Morin, W.D., Leach, J.: Spinal fusion in Duchenne muscular dystrophy – fixation and fusion to the sacropelvis. J. Pediatr. Orthop. 13, 752–757 (1993) Oda, T., Shimizu, N., Yonenobu, K., et al.: Longitudinal study of spinal deformity in Duchenne muscular dystrophy. J. Pediatr. Orthop. 13, 478–488 (1993) Ouellet, J., Arlet, V.: Neuromuscular scoliosis. In: Aebi, M., Arlet, V., Webb, J.K. (eds.) AOSpine Manual. Clinical Applications, vol. 2, pp. 411–435. Thieme, New York (2007) Sengupta, D.K., Mehdian, S.H., McConnell, J.R., et al.: Pelvic or lumbar fixation for the surgical management of scoliosis in Duchenne muscular dystrophy. Spine 27, 2072–2079 (2002) Sussman, M.D., Little, D., Alley, R.M., McCoig, J.A.: Posterior instrumentation and fusion of the thoracolumbar spine for treatment of neuromuscular scoliosis. J. Pediatr. Orthop. 16, 304–313 (1996) Turturro, F., Rocca, B., Gumina, S., et al.: Impaired primary hemostasis with normal platelet function in Duchenne muscular dystrophy during highly-invasive spinal surgery. Neuromuscul. Disord 15, 532–540 (2005) Widman, R.F., Hresko, M.T., Hall, J.E.: Lumbosacral fusion in children and adolescents using the modified sacral bar technique. Clin. Orthop. 364, 85–91 (1999)

 

Other Neuromuscular Disorders with Scoliosis

8

Carol-Claudius Hasler

8.1  Myelomeningocele Spina bifida (disease) is an entity which per definition includes congenital spinal malformations, not only a lack of posterior elements but also as a wide variation of all possible other failures of segmentation and formation and associated malformations of the spinal cord. All patients with MMC have a radiographically tethered cord. As long as they do not present with typical symptoms related to tethering, surgical untethering may not be necessary prior to scoliosis surgery (Samdani et al. 2010). Spinal deformities (impairment) are part of the disease complex. The lower the anatomic paralysis level, the higher the incidence of scoliosis. These curves are usually progressive at a young age and lead to physical disability (loss of function). The patient’s role in society is not only hampered by their neurological deficits but also by spinal deformity (handicap). The core neurological problem is paralysis; however, brain stem and upper cord pathologies may also cause spasticity. Spinal deformity in MMC patients leads to sitting imbalance, deformities of the pelvis, instability of the hips, pressure sores, and impaired arm-hand function in wheelchair-bound patients. The most frequent lumbar and thoracolumbar curves entail high intra-abdominal pressure, a high-standing diaphragm, reduced space available for lungs and subsequent respiratory disability. The up and down movement of the trunk relative to the diaphragm is referred to as the “Marionette sign.” Rigid kyphotic deformities will not be discussed in this chapter. Most coronal plane deformities in these patients are associated with severe sagittal plane deformities. Any correction of deformity before the age of 10 should allow for continued growth to provide normal trunk height, a balanced spine and maximal lung growth. Here, the slower growth rate (growth hormone deficit) and earlier maturation of MMC patients should be taken into consideration. For mild, flexible curves (30–50°) that begin to cause

C.-C. Hasler Orthopaedic Department, University Children’s Hospital, Spitalstrasse 33, 4056 Basel, Switzerland e-mail: [email protected] M. Yazici (ed.), Non-Idiopathic Spine Deformities in Young Children, DOI: 10.1007/978-3-642-19417-7_8, © 2011 EFORT

97

98

8



C.-C. Hasler

sitting imbalance in young children, bracing should be considered though it bears the risk of rib cage deformity, pressure sores, and problems with breathing and eating. If not tolerated, in case of progression or in curves of more than 50–60° in combination with more than 4 years of spinal growth left, a growth-sparing operative intervention is indicated. The goal is final coronal curve magnitude less than 40° and pelvic obliquity less than 15°. Spine-based distraction procedures (double growing rods) are difficult because of the lack of posterior elements: colinear (tandem) or side-to-side connectors, new hybrid anchor types, new remote-controlled implants (currently being introduced) all face the problem of nonexisting or dysplastic caudal anchor points. VEPTR placement is independent of spinal anchoring options and therefore our method of choice. The most common type is a bilateral rib (upper T-spine) to pelvis (S-hook) type of fixation (Eiffel tower construct). The pelvic hook is polyaxial (e.g., allows for selfcatheterization) and can also be placed in difficult anatomic situations associated with hyperlordosis of the lumbosacral junction. The implant’s distance from the central sacral vertical line (lever arm) eases correction of the pelvic obliquity. Excessive forces with lengthening, single rod constructs, and VEPTR for rigid kyphosis should be avoided. New generation VEPTR II provides load sharing with a multiple-anchor points system and is advantageous as bone stock is often very poor. Commonly, the iliac S-hook drifts distally into the ileum over time and should be reseated over the iliac crest if migration goes too far. Intraoperative upper extremity monitoring is important for early detection of brachial plexopathy (direct trauma, positioning, upward displacement of thorax with distraction) which is disastrous for a wheelchair-bound patient’s independency. There are also VEPTRspecific issues: the upper rib cradles may interfere with scapular motion; scapular adhesions, inadvertent fusion of the scapula to the chest (importance of postoperative physiotherapy, early mobilization) may occur; not auto-fusion of the spine but heterotopic ossification along the implant or at the site of former thoracoplasties may take place. Distraction may cause shunt dysfunction with subsequent symptomatic hydrocephalus (nausea, vomiting, impaired vision). Adequate soft-tissue coverage is often a challenge since all patients have already undergone closure for their coele, sometimes in combination with flaps. The risk of skin ulceration and infection is high. Postoperative use of an air mattress is recommended. Toward the end of growth, removal of VEPTR rods and conversion into an instrumented long final fusion or permanent VEPTR rods without further lengthenings is an option; simple removal of the rods, however, is not, as forces deforming the spine will persist throughout life.

8.2  Other Neuromuscular Disorders There is a heterogeneous group of numerous, less-frequent neuromuscular disorders whose common feature is a propensity to develop spinal deformities. Some become only apparent in puberty and warrant instrumented fusion in case of progression, such as unbalancing

8  Other Neuromuscular Disorders with Scoliosis

99

scoliosis in Friedreich ataxia or Rett syndrome (Downs et al. 2009; Labelle et al. 1986). However, in many other entities spinal deformities may develop in childhood when early fusion is not an option. Scoliotic deformities in type-1 Neurofibromatosis, for example, the most frequent autosomal dominant inherited disorder, are either dystrophic or non-dystrophic. The latter is the most common spine deformity in NF-1, similar to idiopathic scoliosis but presenting earlier, stiffer, and more progressively. Dystrophic curves are sharply angulated, short-segmented, mostly kyphoscoliotic, and show more than three of the typical characteristic radiographic features: anterior, posterior or lateral scalloping, vertebral wedging and rotation, enlarged foramina, widened canal, rib-pencilling, and transverse processspindling. Early fusion with or without preoperative traction is indicated, mostly by ­anterior–posterior fusion and posterior instrumentation. However, there are multiple challenges and obstacles to be thoroughly investigated by MRI and considered for planning to prevent major complications: preexisting neurological deficits, intra- and extraspinal neurofibromatomas, rib protrusion into the spinal canal, dural ectasia, excessive bleeding, and vertebral dystrophy which may render hook or screw placement difficult (Crawford et al. 2007). Congenital myopathies (nemaline, myotubular, centronuclear, central core myopathy, multi-minicore, congenital fiber-type disproportion myopathy, hyaline body, and others) represent a heterogeneous group of dominantly inherited diseases defined by their histopathologic abnormalities (muscle biopsy). Their common feature is muscle weakness, and first presentation may range from birth to adulthood (Canavese and Sussman 2009). Correspondingly, the age at onset of scoliosis varies and so does the type of treatment which may range from serial casting to long instrumented fusion (Fig. 8.1a–d). Arthrogryposis multiplex congenita is a diverse mixture of more than 150 disorders characterized by generalized joint contractures and thought to result from failure of normal movement in utero, the cause of which is still unclear. The majority of patients some type of this disorder have contractures of joints affecting all extremities and severe deformities as a result. The most commonly encountered deformities include, but are not limited to, hip dislocations, severe clubfeet, and scoliosis. Depending on the definition chosen, the incidence of scoliotic spinal deformity in arthrogryposis is between 30% and 67% (growing spine). Scoliosis in arthtrogryposis has many features of neuromuscular scoliosis, including lumbar and thoracolumbar involvement, stiffness, and rapid progression (sometimes up to 6.5°/year). The deformity may be present at birth, develop during the first year of life, be associated with pelvic obliquity and, while good results have been reported, is usually refractory to conservative treatment. Owing to the rarity of the disorder, reports of surgical treatment are rare but in most series, curves have been observed to show rapid progression and stiffening. Curves exceeding 40°, presenting with marked hyperkyphosis, hyperlordosis, or pelvic obliquity should be treated surgically without delay. Because of jaw contracture, difficulties in intubation may arise (Nguyen et al. 2000). The myriad of joint contractures may complicate positioning for spinal surgery. The method usually chosen for patients approaching skeletal maturity is instrumented fusion, which has been shown to effectively correct and halt progression of the deformity (Herron et  al. 1978). Younger patients with greater

100 

8

C.-C. Hasler

amounts of growth remaining should be considered for growth-sparing interventions such as the VEPTR (accompanied by multiple concave hemithorax opening wedge thoracostomies due to the stiff nature of the rib cage) or double growing rod constructs. Results of instrumented fusion, while old and performed with outdated implants, are generally good; however, the efficacy of growth-preserving methods remains to be determined (Fig. 8.2a–e). Prader–Willi syndrome occurs due to the deletion, duplication, or otherwise alteration of the paternal copy of the chromosome 15q. The syndrome affects 1 in 15,000 infants and males three times as often as females. Diagnostic criteria established by Holm et al. include muscular hypotonia (improves in the first year of life), short stature, narrow forehead, obesity, ligamentous hyperlaxity, hypogonadism, diabetes mellitus, developmental delay, and mental retardation (Holm et  al. 1993). Orthopedic afflictions commonly

a

b

Fig. 8.1  (a, b) A 6-year-old still ambulating girl with congenital myopathy and a right convex thoracolumbar curve which progressed despite brace treatment to 100° Cobb angle and severe loss of balance which threatened the walking ability. (c, d) To provide further growth, correct pelvic obliquity, and control the upper thoracic compensatory curve, a triple VEPTR construct was implanted with subsequent 50% curve correction. The trunk was not fully rebalanced to compensate for the head tilt and cervical scoliosis. At the age of 10 years, after six VEPTR lengthenings, the deformity is under control and the patient regained her preexisting walking capacity

101

8  Other Neuromuscular Disorders with Scoliosis

c

d

Fig. 8.1  (continued)

encountered in this patient population are camptodactyly, genu valgum, and osteoporosis, while the reported incidence of scoliosis is 45–86% and kyphosis, 40% (Greggi et  al. 2010). Scoliosis appears to behave like adolescent idiopathic scoliosis with a high risk of progression during adolescence and is reported to require active treatment in up to 20% of cases. As it is associated with the deficiency of growth hormone, this substance is used in the treatment of the disease and concerns exist regarding its effect on scoliosis in this patient group. Two types of curves in patients with Prader–Willi syndrome have been described. The first is the long, sweeping C-shaped curve similar to other neuromuscular ­disorders and the second resembles idiopathic scoliosis. Hypotonicity and early age at presentation were found to be associated with the former (de Lind van Wijngaarden et al. 2008). The

102 

8

C.-C. Hasler

resemblance of most curves to idiopathic ­scoliosis has given incentive to use brace therapy for management, but curve progression may proceed despite the brace and with increasing obesity its beneficial effects decrease. Compliance might be low in this mentally retarded patient group. Kyphosis has been found to be associated with increased body-mass index and kyphoscoliosis is thought to contribute to trunk imbalance and requirement for surgery (Odent et al. 2008).While not clearly established in the literature, severe curves showing progression should be considered for surgical treatment. Posterior instrumentation and fusion remains the procedure of choice for the majority

a

b

Fig. 8.2  (a–c) A 12-year-old girl with myopathy and progressive, rigid scoliosis (rigid spine syndrome) including the cervical spine. Failure of brace treatment (curve progression, pain, pressure sores). Impaired walking capacity due to increasing loss of balance, decreasing respiratory function, and loss of weight. Despite growth retardation and premenarcheal status it was decided to definitively correct and fuse. (d–f) Two years post-T2-iliosacral hybrid instrumentation. In regard of the poor soft tissue coverage at the level of the thoracic spine, we chose sublaminar Luque wire which represent the most low profile way of fixation. In agreement with the patient, the cervical curve was not instrumented but supported for 3  months postoperatively with a soft neck collar. Uneventful healing with regain of weight, walking capacity, and stabilization of pulmonary function

103

8  Other Neuromuscular Disorders with Scoliosis

c

Fig. 8.2  (continued)

d

104 

8

e

C.-C. Hasler

f

Fig. 8.2  (continued)

of patients. A high rate of complications has been reported in this patient group, the most common of which is cervicothoracic collapse into severe kyphosis above the instrumentation, infections and wound complications, pulmonary complications, and an increased risk of neurological events (Accadbled et al. 2008). Osteopenia, difficulties in impulse control, and other psychiatric disorders and decreased sensitivity to pain are other factors that might complicate the orthopedic treatment of patients with Prader–Willi syndrome (Kroonen et al. 2006).

8  Other Neuromuscular Disorders with Scoliosis

105

References Accadbled, F., et al.: Complications of scoliosis surgery in Prader-Willi syndrome. Spine (Phila 1976) 33(4), 394–401 (2008) Canavese, F., Sussman, M.D.: Orthopaedic manifestations of congenital myotonic dystrophy during childhood and adolescence. J. Pediatr. Orthop. 29(2), 208–213 (2009) Crawford, A.H., et al.: The immature spine in type-1 neurofibromatosis. J. Bone Joint Surg. Am. 89(Suppl 1), 123–142 (2007) de Lind van Wijngaarden, R.F., et al.: Scoliosis in Prader-Willi syndrome: prevalence, effects of age, gender, body mass index, lean body mass and genotype. Arch. Dis. Child. 93(12), 1012–1016 (2008) Downs, J., et  al.: Guidelines for management of scoliosis in Rett syndrome patients based on expert consensus and clinical evidence. Spine (Phila 1976) 34(17), E607–E617 (2009) Greggi, T., et  al.: Treatment of scoliosis in patients affected with Prader-Willi syndrome using ­various techniques. Scoliosis 5, 11 (2010) Herron, L.D., Westin, G.W., Dawson, E.G.: Scoliosis in arthrogryposis multiplex congenita. J. Bone Joint Surg. Am. 60(3), 293–299 (1978) Holm, V.A., et al.: Prader-Willi syndrome: consensus diagnostic criteria. Pediatrics 91(2), 398–402 (1993) Kroonen, L.T., et  al.: Prader-Willi syndrome: clinical concerns for the orthopaedic surgeon. J. Pediatr. Orthop. 26(5), 673–679 (2006) Labelle, H., et al.: Natural history of scoliosis in Friedreich’s ataxia. J. Bone Joint Surg. Am. 68(4), 564–572 (1986) Nguyen, N.H., Morvant, E.M., Mayhew, J.F.: Anesthetic management for patients with arthrogryposis multiplex congenita and severe micrognathia: case reports. J. Clin. Anesth. 12(3), 227–230 (2000) Odent, T., et al.: Scoliosis in patients with Prader-Willi syndrome. Pediatrics 122(2), e499–e503 (2008) Samdani, A.F., et al.: The patient with myelomeningocele: is untethering necessary prior to deformity correction? In: 45th annual meeting of the Scoliosis Research Society, Kyoto (2010)

 

Part IV Management

 

Delaying Tactics: Traction, Casting, and Bracing

9

Charles E. Johnston II

An increasing awareness of the potential for thoracic insufficiency syndrome (Campbell et al. 2003) to develop in patients with early onset spinal deformity, regardless of etiology, has stimulated interest in delaying definitive spinal fusion for as long as possible. The increased respiratory morbidity and mortality now recognized in the early onset patient make a compelling case for controlling the deformity while allowing spinal and lung growth to continue, as the untreated deformity relentlessly impairs pulmonary growth and function by inhibition of alveolar development (intrinsic impairment) and mechanical chest wall function (extrinsic impairment) (Herring 2008), and is documented to produce excessive early mortality (Pehrsson et al. 1992). Unfortunately, it is also now established that fusion of the thoracic spine at an early age – the classic orthopedic procedure to treat progressive scoliosis – can be equally detrimental, depending on the location (proximal thoracic vs. distal) and number of thoracic segments fused (five or more), to pulmonary function by interrupting spine and thorax growth during the critical first 5 years of life (Goldberg et al. 2003; Emans et al. 2004; Karol et al. 2008). It is important now to reexamine our approach to young children with even ­small-to-modest magnitude spinal deformities. The principle of a short straight spine, produced by an early fusion, being better than a long curved spine is no longer automatically accepted. Avoiding fusion of the thoracic spine, especially proximal segments prior to age 5 (Karol et al. 2008), is the goal of management, but must control spinal deformity without impeding thoracic growth, delaying definitive fusion until age 10 if possible (Goldberg et al. 2003). Current innovative techniques such as expansion thoracoplasty or growth-­sparing spine instrumentation (“growing rods”) offer the possibility of prevention of thoracic insufficiency from spine deformity by re-correcting and/or lengthening the spine and/or thorax at regular intervals (e.g., every 6 months). It goes without ­saying, however, that such repeated

C.E. Johnston II Texas Scottish Rite Hospital, 2222 Welbon Street, Dallas, TX 75219-3924, USA e-mail: [email protected]

M. Yazici (ed.), Non-Idiopathic Spine Deformities in Young Children, DOI: 10.1007/978-3-642-19417-7_9, © 2011 EFORT

109

110 

9

C.E. Johnston II

surgical procedures in young, often diminutive, patients are frequently complicated by loss of fixation from bone-anchor failure, implant failure, wound dehiscence and infection, neurologic injury, chest wall and spinal rigidity from scar tissue and unintended immobilization of intercalary segments (ribs or vertebrae), and development of junctional deformities at the ends of instrumented segments. Attempting to delay the application of these surgical growth-sparing techniques is intuitively advantageous, to decrease the chances for complications due to better bone stock for implant anchorage in an older (larger) patient and a fewer number of procedures being required in the older child. However, implicit in any treatment method intended to delay surgical management must be the ability to control the deformity, with the goal of preventing any degradation of pulmonary function, intrinsic or extrinsic. The use of nonoperative methods to delay surgical treatment in patients at risk for thoracic insufficiency is often the first approach to the long-term management of early onset spinal deformity.

9.1  Bracing Bracing is a time-honored method to control a deformity which is not congenital and where the patient does not have neuromuscular or other medical conditions where a brace could effect respiratory function directly by circumferential chest or abdominal compression (Fig. 9.1). Bracing efficacy is difficult to define or to prove by standard criteria of success, as most curves can be improved radiographically by well-constructed orthoses, even in the smallest patients, only to progress later with growth. Orthotic management is intended to prevent progression for several years allowing fusion to be delayed. If fusion can be delayed to age 10 the need for anterior fusion may be avoided (Johnston et  al. 1982), as well as improving the pulmonary outcome (Goldberg et al. 2003). On the other hand, brace management in the rapidly growing child under age 5 must be carefully evaluated for brace-induced rib deformity, produced by pressure on a moldable infantile rib cage, as well as obliteration of normal sagittal contour (lumbar hypolordosis and thoracic hypokyphosis). Iatrogenic rib and sagittal spine deformity (Fig.  9.2) and volume restriction must not add to the existing deformities. The Milwaukee brace, in some form, is often the orthosis of choice in the early onset patient, due to the ability to apply corrective forces directly at the apex of the curve, at the pelvis, and at the neck, while minimizing the constrictive aspects of a TLSO. Precise, custom construction is essential to success. Respiratory effort and rib compression must be minimally affected. A well-fitted orthosis is often accepted easily by the child <6 years of age, with poor acceptance being an indication of poor brace fit, which is often due to progression and increased rigidity of the deformity.

111

9  Delaying Tactics: Traction, Casting, and Bracing

a

b

c

Fig. 9.1  (a–c) A 3-year-old boy with Eagle–Barrett (prune belly) syndrome and scoliosis. Orthotic management of his scoliosis is impossible due to absence of abdominal wall musculature, an overly compressible thoracic cage, and bilateral posterior ureterostomies

112 

9

C.E. Johnston II

Fig. 9.2  Iatrogenic worsening of deformity by prolonged bracing. This child’s lumbar curve increased and the lower right ribs were indented by posterolateral forces from prolonged external pad pressure

9.2  Casting Casting is a more aggressive step in prolonging the nonoperative management of the young child with progressive deformity. One indication for casting is inability to control curve progression with a brace, but still attempting to delay surgical intervention. As the deformity increases in severity and stiffness, the patient may be unable to tolerate a brace. A series of casts applied under anesthesia can produce significant curve correction and may improve flexibility. When the child resumes brace wear after several months in cast, the deformity is smaller, making a brace more comfortable and thus more likely to control the curve. In addition, since the cast is equivalent to a full-time brace which cannot be removed, many parents find it preferable to braces, since the problems of compliance and the difficulties of donning braces in uncooperative young children are eliminated. Moreover, casting can be an effective definitive management, more than simply a delaying tactic. Mehta (2005) has recently reviewed a 20+-year experience treating infantileonset, non-congenital scoliosis with serial casts. Her technique involves primarily manual derotation of the rib deformity from posterior as the plaster dries, with appropriate countermolding anteriorly. Longitudinal traction is used only to maintain the patient suspended while the cast is applied (Fig. 9.3). A generous window can be removed posteriorly from the concavity of the scoliosis, to allow the spine to gradually move into this potential space and improve transverse correction (Fig. 9.3c). Patients casted aggressively beginning at age 19 months (average curve 32°) had their scoliosis reduced to <10° at maturity. Patients starting treatment later (mean 30 months), with larger curves averaging 52°, did not gain significant correction, but their deformities had not progressed (46°) at follow-up. The protocol required serial cast changes under anesthesia every 2–3 months in children under 2 years, with a minimum of five casts and the goal of achieving a straight spine, at which

9  Delaying Tactics: Traction, Casting, and Bracing Fig. 9.3  (a) Mehta method of traction for cast application. Note there is no support for the patient between the base of the neck and the upper posterior thighs except the longitudinal traction (Courtesy of J.A. d’Astous, MD). (b) Derotation of the rib deformity by posterolateral molding (in this case of a left convexity) with anterior molding on the right (Courtesy of J.A. d’Astous, MD). (c) Windowing of concavity of cast

a

b

c

113

114 

9

C.E. Johnston II

time the patient was switched to a brace. Children over age 2 require cast changes every 3–4  months. Older children demonstrating “recurrence” are placed back in a cast for 4 months to re-correct the deformity before continuing with brace management. Mehta’s important contribution is the demonstration that serial casting in young children – even infants – if pursued aggressively and for a long enough period of time, can in fact serve to correct the deformity over long follow-up. Serial casting using a traditional Risser table, with neck halter and pelvic strap longitudinal traction and appropriate localized hand pressure for transversely applied molding directly to the rib hump can also be successful (Fig. 9.4a). A properly molded neck piece maintains the longitudinal corrective force once the traction is removed. A large abdominal window is removed for respiratory excursion, and other cast relief provided from portions which do not involve spine corrective forces (Fig. 9.4b). Deformity correction can be dramatic in the short term (Fig.  9.4c, d), realizing the apparent correction is somewhat

a

b

Fig. 9.4  (a) Classic Risser cast traction. Note the central strap support and the hip extension, to maintain normal lumbar lordosis. (b) Completed cast with neck mold and large abdominal window. (c, d) Pre- and post-cast radiographs of this patient

115

9  Delaying Tactics: Traction, Casting, and Bracing Fig. 9.4  (continued)

c

d

misleading since the radiograph is taken supine (compared to a pretreatment standing film). Nevertheless, by serial cast changes, usually a minimum of three, performed every 2–3 months for a period of 6–9 months, the apparently uncontrollable, rapidly progressive deformity can be corrected sufficiently to return to orthotic management and obtain further delay in the need for surgery. Besides skin irritation or decubiti, complications of casting include the superior mesenteric artery syndrome and neurologic dysfunction, particularly affecting cranial nerves and the brachial plexus if the neck portion is applied with too much head/shoulder distraction. Longer term, as mentioned in the bracing discussion, one must be vigilant that a constrictive molding of the chest does not occur, especially in patients who may not be cognitively normal. For this reason, as well as the pressure sore issue, such patients may have a relative contraindication for casting. While it may be argued that a cast restricts pulmonary function more than a brace, and may cause more rib deformations, these drawbacks can be minimized by careful experienced cast application. Although casting is clearly useful in delaying surgery, it is not for every patient and not for every surgeon.

9.3  Halo-Gravity Traction (HGT) Some patients with progressive deformity are not candidates for casting, for example, due to weakness, abdominal or chest wall defects, skin intolerance, or mental retardation. Large, stiff curves may not benefit from serial casting, and the cast may be poorly ­tolerated.

116 

9

a

C.E. Johnston II

b

c

Fig. 9.5  (a) Pretreatment lateral radiograph of a 6-year-old boy with quadriparesis related to upper cervical stenosis with Conradi’s syndrome (note occipital-cervical fusion). (b) Improved kyphosis now makes the patient a more receptive candidate growing rod instrumentation. (c) Growing construct was implanted with much less contouring and surgical difficulty due to correction achieved in traction

In these instances, halo-gravity traction (HGT) has been an invaluable method to achieve deformity correction, and indirectly, improve respiratory mechanics (Fig. 9.5) (Sink et al. 2001; Walick et al. 2008). HGT is very much a European technique, developed originally by Stagnara (1971) and later demonstrated to the author by Zielke on a visit to the latter’s clinic in 1984. Halo application requires anesthesia using a minimum of six to eight pins in this age group (Fig. 9.6c) (Mubarak et al. 1989; Herring 2008). Experience has shown that more pins actually decrease the chance of infection or loosening of any single pin. Pins are tightened to a torque equalling the age of the child – e.g., a 4-year-old patient’s pins are tightened to 4 in.-lb of torque, using a calibrated torque wrench. The following day the patient is placed upright in overhead traction via a traction bale attached to a wheelchair or standing frame, using a spring-loaded fish scale (Fig. 9.6) or other dynamic (not fixed weight) traction device, with an initial traction of 5–10 lb. The time in traction and amount of weight is increased to tolerance with careful neurologic monitoring. All patients need cranial nerve testing while upright in traction as well as upper and lower extremity

Fig. 9.6  (a) Dynamic traction via a spring-loaded fish scale. Traction load increases as the horizontal bar is raised on the vertical upright. (b) Patients can be extremely active while in overhead walkingframe traction. (c) Typical pin configuration for halo application in small children

117

9  Delaying Tactics: Traction, Casting, and Bracing

a

c

b

118 

9

C.E. Johnston II

strength and reflex monitoring. Traction force exceeding 50% of body weight may be achieved. The traction is increased so that the patient’s buttocks are lifted slightly off the wheelchair seat while sitting, and in the standing frame the patient should be just up on tiptoes (Fig. 9.6b). The safety of the method is provided by the ability of the patient to auto-relieve the traction force by pushing up on the wheelchair arms or walker hand rails when necessary for pain or impending neurologic symptoms. Patients in fixed-weight traction (traditional ropes and pulleys) cannot relieve the force by pushing themselves up (D’Astous and Sanders 2007). Many patients can be treated as outpatients once caretakers are educated and comfortable with traction supervision. Only two neurologic complications have occurred in our series of nearly 100 patients. One patient with Klippel–Feil syndrome and multiple cervical synostoses developed mouth and facial numbness when C3–4 disruption occurred at the only non-fused level in the neck. This resolved after traction was discontinued and converted to a halo vest for 6 weeks. A second patient with incomplete resection of an intramedullary ganglioneuroma with preexisting hyperreflexia developed increased lower extremity weakness necessitating traction discontinuance, with incomplete recovery. Another report of 62 patients treated in traction noted nystagmus, sensory changes, and one possible cranial nerve lesion in nine patients (Kuklo et al. 2008). It is generally agreed that traction for any patient with preexisting stenosis or a mass-occupying lesion of the canal or cord is contraindicated (Emans et al. 2007). The only other absolute contraindication to HGT is insufficient bone in the skull to provide adequate pin purchase. Various cranial-deficient diagnoses, such as osteogenesis imperfecta or fibrous dysplasia, must be evaluated on an individual basis for halo suitability. Long-term HGT is especially useful in correcting trunk shift, trunk height, and sagittal plane deformity. Effective improvement in trunk shift and the coronal deformity over an average of 13 weeks (range 6–28) in traction prior to definitive posterior instrumentation and fusion has been reported (Rinella et al. 2005; Sink et al. 2001; Walick et al. 2008). Kyphosis correction and trunk height increase are also significant (Fig. 9.5) and probably explain improved pulmonary function during traction, so that definitive surgery can be delayed until serial PFTs show that improvement has plateaued. Similar efficacy has been confirmed by Kuklo et al. (2008). The ability to mobilize patients with weakness, osteopenia, and respiratory compromise during the traction period is invaluable in preparing such patients for either casting or surgery. HGT avoids enforced bedrest, as is required by halofemoral traction, and there is significant pulmonary benefit from an upright thorax. Finally, since these children have diminutive, often osteopenic spinal elements and more rigid deformities, acute correction of their deformity with instrumentation may be compromised by bone–implant interface failure and neurologic risk. Thus correction of their spine, not to mention the length of their thorax, must be done gradually with increasing traction (Figs. 9.5 and 9.7). The definitive stabilization procedure using instrumentation may then become essentially an in situ fixation to maintain the position achieved by traction. More recently, HGT has been proposed as an indispensable preliminary adjunct to implanting fusionless constructs (Emans et al. 2007). Because of the kyphosis correction, proximal anchors (rib or spine) can be placed with greater security and longitudinal members not contoured as severely, making subsequent lengthening less problematic (Fig. 9.5).

119

9  Delaying Tactics: Traction, Casting, and Bracing Fig. 9.7  (a, b) A 100° scoliosis in an 18-month-old child was corrected to 65° after 1 month of HGT (same patient as in Fig. 9.6b)

a

b

References Campbell Jr., R.M., Smith, M.D., Mayes, T.C., et al.: The characteristics of thoracic insufficiency syndrome associated with fused ribs and congenital scoliosis. J. Bone Joint Surg. Am. 85-A, 399–408 (2003) D’Astous, J.L., Sanders, J.O.: Casting and traction treatment methods for scoliosis. Orthop. Clin. North Am. 38, 477–84g (2007) Emans, J.B., Kassab, F., Caubert, J.F., et al.: Earlier and more extensive thoracic fusion is associated with diminished pulmonary function. Paper #101. In: 39th Scoliosis Research Society, Buenos Aires, 6–9 Sept 2004 Emans, J.B., Johnston, C.E., Smith, J.T.: Preliminary halo-gravity traction facilitates insertion of growing rods or Veptr devices in severe early onset spinal deformity. Paper #43. In: 42nd Scoliosis Research Society, Edinburgh, 5–8 Sept 2007 Goldberg, C.J., Gillic, I., Connaughton, O., et al.: Respiratory function and cosmesis at maturity in infantile-onset scoliosis. Spine 28, 2397–406 (2003) Herring, J.A. (ed.): Tachdjian’s Pediatric Orthopedics, 4th edn, p. 358. Saunders/Elsevier, Philadelphia (2008) Johnston II, C.E., Hakala, M.W., Rosenberger, R.: Paralytic spinal deformity: orthotic treatment in spinal discontinuity syndromes. J. Pediatr. Orthop. 2, 233–41 (1982) Karol, L.A., Johnston, C.E., Mladenov, K., et  al.: Pulmonary function following early thoracic fusion in non-neuromuscular scoliosis. J. Bone Joint Surg. Am. 90-A, 1272–81 (2008) Kuklo, T.R., Keeler, K.A., Meyer, L.A., et  al.: Is extended preoperative halo traction safe and effective for severe pediatric spinal deformity? Paper #81. In: 43rd Scoliosis Research Society, Salt Lake City, 10–13 Sept 2008

120 

9

C.E. Johnston II

Mehta, M.H.: Growth as a corrective force in the early treatment of progressive infantile scoliosis. J. Bone Joint Surg. Br. 87, 1237–47 (2005) Mubarak, S.J., Camp, J.F., Vuletich, W., et al.: Halo application in the infant. J. Pediatr. Orthop. 9, 612–4 (1989) Pehrsson, K., Larsson, S., Oden, A., et al.: Long-term follow-up of patients with untreated scoliosis. A study of mortality, causes of death, and symptoms. Spine 17, 1091–96 (1992) Rinella, A., Lenke, L., Whitaker, C., et al.: Perioperative halo-gravity traction in the treatment of severe scoliosis and kyphosis. Spine 30, 475–82 (2005) Sink, E.L., Karol, L.A., Sanders, J., et al.: Efficacy of perioperative halo-gravity traction in the treatment of severe scoliosis in children. J. Pediatr. Orthop. 21, 519–24 (2001) Stagnara, P.: Cranial traction using the “halo” of Rancho Los Amigos. Rev. Chir. Orthop. 57, 287–300 (1971) Walick, K., McClung, A., Sucato, D.J., et al.: Halo-gravity traction in severe pediatric spinal deformity. Paper #80. In: 43rd Scoliosis Research Society, Salt Lake City, 10–13 Sept 2008

Indications for Non-fusion Operative Techniques in Non-Idiopathic Scoliosis

10

Charles E. Johnston II

As discussed in Chap. 8, current management of early onset scoliosis (EOS) of any ­etiology should focus initially on avoiding treatment methods (i.e., spinal fusion) which can produce iatrogenic inhibition of spinal and/or chest wall growth over and above that which is due to the underlying condition. When discussing non-idiopathic etiologies, especially congenital or syndromic diagnoses where vertebral growth may be extensively inhibited by the nature of the anomaly, treatment decisions, especially for operative methods, must carefully evaluate realistic growth potential for the patient and, as with any decision to move from delaying tactics to operative treatment, demonstrate compelling reasons to forego or abandon nonsurgical methods. Once operative treatment is selected, non-fusion techniques need to be based on the age and growth potential. However, since most current non-fusion techniques involve serial re-correction of the deformity, committing the patient and surgeon to repeated procedures as frequently as twice a year for several years, with potentially a 100% incidence of complication (i.e., every patient is expected to have a complication at some point in the treatment), it is crucial for this decision to be based on measurable data and serial studies documenting the need for more aggressive treatment, with the goal of avoiding thoracic insufficiency syndrome (TIS) – the inability of the thorax to support lung growth and normal respiration (Campbell et al. 2003).

10.1  Decision Making: Etiology Often a non-fusion operative method is indicated by the etiology of the deformity. Patients with congenital scoliosis or kyphosis will not benefit from bracing or casting, for example, due to the structural nature of the deformity, which cannot respond to or be corrected by a nonoperative method. In selected patients with short-segment congenital deformities, involving four or less apical segments, casting or bracing may be attempted to control a

C.E. Johnston II Texas Scottish Rite Hospital, 2222 Welbon Street, Dallas, TX 75219-3924, USA e-mail: [email protected] M. Yazici (ed.), Non-Idiopathic Spine Deformities in Young Children, DOI: 10.1007/978-3-642-19417-7_10, © 2011 EFORT

121

122 

10

C.E. Johnston II

non-congenital deformity outside the anomalous segment which is either adding to the overall curve or producing a compensatory one. However, definitive surgical management of the short segment, with correction by resection and/or instrumented fusion, may be more effective while shortening the treatment time to the perioperative period only. Since the anomalous short segment, fused or unfused, potentially provides minimal spinal length, treatment by early resection and arthrodesis sacrifices no additional length, and by removing the asymmetrical apical growth, allows the segments outside the anomalous apex to grow unencumbered and hopefully without further deformity. In patients with more extensive congenital anomalies (e.g., more than four thoracic segments), where nonoperative methods cannot be expected to have any effect, the decision for non-fusion operative technique is intuitive, as maintenance of spinal length and control of axial plane deformity are both required. Other etiologies where a non-fusion operative method may be initially chosen include neuromuscular or syndromic hyperlaxity deformities (Figs. 10.2 and 10.3), where external pressure from cast or brace may cause respiratory impairment, either by chest wall pressure inducing rib “molding” deformity and further narrowing of the convex hemi-thorax, or by restricting abdominal excursion in patients who are primarily diaphragmatic breathers. Such patients may have a strong indication for preliminary halo-gravity traction due to kyphosis in the mid-to-upper thoracic spine, which initially presents a relative contraindication to fusionless instrumentation (see Chap. 12). Of course there are also patients with skeletal dysplasias and short trunks (e.g., achondroplasia) who are simply not candidates for cast or brace due to body habitus, and thus may become candidates for non-fusion instrumentation methods in order to prevent deformity progression while maximizing ­limited spinal length potential.

Case Example A 9-month-old, otherwise healthy female with congenital scoliosis and rib fusions presented with a 57° scoliosis T3–L1 (Fig.  10.1a). Physical examination showed normal respiratory effort on the right hemi-thorax, with some impairment on the left. The patient was followed, but by age 2, there had been little longitudinal growth of the spine (Fig.  10.1b–d), as measured by T1–12 length, and the scoliosis had progressed to 76°. The lack of longitudinal growth was of particular concern, considering the length was well below the 5th percentile (Fig. 10.1d) and declining due to lack of growth and increased deformity. This lack of growth presented an absolute indication for non-fusion lengthening technique, since no nonoperative method could be expected to improve this congenital deformity. The patient underwent expansion thoracoplasty with rib fusion lysis and placement of a rib-to-rib VEPTR as well as a rib-to-spine rod system on the concavity. Subsequently, two further lengthenings have been accomplished (Fig. 10.1e), and CT lung volumes have documented relative increase in left lung volume (expanded side) compared to the right which is the “control” side (Fig. 10.1f, g). Spinal and thoracic contours are improved (Fig. 10.1h), with minimal axial defor­mity by CT.

10  Indications for Non-fusion Operative Techniques in Non-Idiopathic Scoliosis

a

123

b

c

Fig. 10.1  (a) Initial radiograph. There is a 57° congenital scoliosis, with fused ribs visible. The T1–12 length = 9.3 cm (normal newborn thoracic length 11–12 cm Dimeglio and Bonnel 1990). (b) Age 2 + 1, the curve has increased to 76°, with insufficient thoracic length gain (=9.7  cm). (c) Clinical appearance. The hypoplasia of the left hemi-thorax is obvious

124 

d

35 Mean value Upper and lower 95% limits

30 Thoracic spine height (cm)

10

C.E. Johnston II

25

20

15

10

5

0 3

e

4

5

6

7 8 9 10 Pelvic width (cm)

11

12

13

14

f

Fig.  10.1  (continued) (d) Growth of the thoracic spine, plotted on Emans’ chart for normal individuals. The length of the thoracic spine is <5th percentile and decreases with time. Note the x-axis measure is the pelvic inlet width, to assess spine length independent of chronologic age. (e) Following expansion thoracoplasty and two subsequent lengthening procedures, the left hemithorax is visibly enlarged, the T1–12 length = 12.6 cm and the scoliosis is 34°. (f) CT lung volume, age 10 months; R lung = 132 cc, L = 114 cc

10  Indications for Non-fusion Operative Techniques in Non-Idiopathic Scoliosis

g

125

h

Fig. 10.1  (continued) (g) CT lung volume age 3, 1  year s/p surgery (includes one lengthening). R lung = 279 cc, L = 345 cc. The concave left lung (treated) has tripled in volume during the same time period that the convex right lung has doubled, indicating effective expansion of the concave side. (h) Clinical appearance age 3. The left hemi-thorax has increased in size and spinal balance is improved

Fig. 10.2  (a–c) Clinical appearance of a 5-year-old male with spinal muscular atrophy. Due to collapsing kyphoscoliosis, he was no longer able to tolerate a brace due to pain and restriction of abdominal movement

126 

C.E. Johnston II

10

Fig.  10.3  (a, b) Standing radiographs, age 5. (c) Traction radiograph demonstrating marked flexibility. The kyphosis was also flexible, making preliminary traction unnecessary for growing rod implantation

10.2  Assessment of Deformity Progression Nonoperative delaying tactics may eventually fail, with both progression of deformity as well as declining growth and respiratory function. A decision to move ahead with a nonfusion operative method may be suggested by such a turn of events. It has become increasingly obvious, as experience with EOS increases, that the threedimensional deformity involving spine and chest wall – the underlying essential pathoanatomy of TIS – cannot be well understood or assessed by a simple Cobb angle measurement, for example. While inexorable increase in angular deformity despite nonoperative management is certainly a relative indication for an operative approach, other measures of the deformity, beyond spinal angular measures, are required in order to fully assess for, and then justify non-fusion treatment options. Since growth of the spine – or rather, continued increase in the spinal length – is a major factor in increasing thoracic volume, measurement of the T1–12 length in coronal and sometimes sagittal planes is appropriate (Fig.  10.4a), with comparison of the length to standards determined by Emans et al. (2005) for normal children, based on the width of the pelvic inlet (Fig. 10.4b), so as to make the length determination independent of age. Such length determinations performed serially and plotted on the length-to-pelvic width graph (Fig. 10.4c) provide an important indication of whether the thoracic growth is slowing or falling behind, whether due to increased angular deformity (which could be addressed by

127

10  Indications for Non-fusion Operative Techniques in Non-Idiopathic Scoliosis Fig. 10.4  (a) Measurement method for T1–12 length and T6 thoracic width. (b) Measurement of pelvic inlet width. (c) Graph of thoracic length vs. pelvic width (Emans 2005). This “growth chart” of the thoracic length monitors the adequacy of thoracic spine growth in comparison to normal subjects

a T1

T6 Thoracic width

T12 T1 – T12 Thoracic width

b

Pelvic width

128 

c

35 Mean value 30

Thoracic spine height (cm)

10

C.E. Johnston II

Upper and lower 95% limits

25

20

15

10

5 0 3

4

5

6

7 8 9 10 Pelvic width (cm)

11

12

13

14

Fig. 10.4  (continued)

corrective spinal techniques) or due to growth inhibition by congenital or syndromic anomalies, which might be addressed by spine or chest wall distraction methods (Fig. 10.1). Increasing axial plane deformity in the form of spinal penetration into the convex hemithorax (Dubousset et al. 2002) ultimately produces the constricted, “windswept” thorax (Campbell type IIIb) leading to TIS in patients without congenital chest wall anomalies (Campbell and Smith 2007). As the scoliosis progresses, spinal penetration into the convex hemi-thorax is accompanied by a narrowing of the thoracic cavity (Fig. 10.5) and loss of compliance of the convex chest wall due to stiffening by the rib hump deformity. Known as the extrinsic disturbance to respiratory function (Herring 2008), chest wall dysfunction (noncompliance) is most severe when ribs are fused or absent – which in general only affects the concave hemi-thorax. In non-congenital deformity, ribs on the concavity become crowded, unable to allow efficient intercostal expansion for inspiration. Meanwhile, the convex rib deformity has widened intercostal spaces, which cannot contract due to stiff rib deformity to generate expiratory function. This convex deformity is best assessed by CT scan of the chest, where the extent of narrowing of the lung field and the bony encroachment of lung space by the rib deformity are easily visualized/quantitated (Fig. 10.5). Additionally, deformity such as rib penetration into the spinal canal (neurofibromatosis), chronic atelectasis, non-aerated segments of lung, or simply hypoplastic segments of lung are also diagnosed. Finally, lung volume can be calculated from the CT slices (Fig. 10.1), acquiring anatomic volume data which act as a surrogate for pulmonary function in patients too young to perform standard pulmonary function testing, usually children under age 5–6. That CT volume can then be compared to

129

10  Indications for Non-fusion Operative Techniques in Non-Idiopathic Scoliosis

a

b

Fig.  10.5  (a) A 4-year-old male with a left thoracic scoliosis due to treatment in infancy for intrathoracic neuroblastoma. (b) CT at the apex, demonstrating the penetration of the spine into the left hemi-thorax, with obvious diminution of left lung volume due to narrowing by the rib deformity – the “windswept” thorax

Total lung volume (cc)

Total lung volume – Males 8000 7500 7000 6500 6000 5500 5000 4500 4000 3500 3000 2500 2000 1500 1000 500 0 0

1

2

3

4

5

6

7 8 9 Age (years)

10

11

12

13

14

15

16

17

18

Fig. 10.6  Normal CT lung volumes according to age (Gallogly et al. 2004)

“normal” age-based data (Gallogly et al. 2004, Fig. 10.6), which when collected serially, provides another measure of thoracic growth and, more importantly, documents the enlargement of the hemi-thorax during treatment (Fig. 10.1g), or indicates when volume growth is falling behind. Currently, serial CT scanning of the chest performed annually or

130 

C.E. Johnston II

10

Fig. 10.7  (a) A 3-year-old female with an 82° congenital scoliosis and normal thorax. Multiple thoracic and lumbar anomalous vertebrae are present. A large trunk shift is present. T1–12 length = 13.1 cm. (b, c) 3-D CT reconstructions showing discordant anterior and posterior failures of segmentation at T7–9 apex. (d) Control of the apex required eggshell hemi-vertebrectomy of T8, with correction by compression of T7–9 segment via convex pedicle fixation. No exposure of the concavity was performed. A growing rod construct from high thoracic to L4 was placed to span the entire curve. One year later, following lengthening and in situ contouring of both rods at the apex, the curve is reduced to 45° with excellent balance. (e, f) Most recent follow-up 4  years ­post-op. Scoliosis now measures 40°, and T1–12 = 18  cm, with normal sagittal alignment. The gradual corrective lateral bending of the rods has translated the apex out of the convex hemi-­ thorax, preventing a constricted thorax deformity

10  Indications for Non-fusion Operative Techniques in Non-Idiopathic Scoliosis

131

bi-annually, is our best method to evaluate lung growth and the effects of treatment. Additionally, by increasing awareness of the spine penetration deformity into the windswept thorax, newer concepts of deformity correction by “guided growth” have been developed. Examples include control of the apical convex vertebrae by growing instrumentation which can be progressively contoured in situ with each planned lengthening procedure to translate the apex toward the concavity (Fig. 10.7); or aggressive one-time correction and fusion of the apical deformity with non-fused implants at end vertebrae which can slide along rods left purposefully long to guide the growth of the ends of the curve (“Shilla” procedure, McCarthy et al. 2008). Body weight is increasingly recognized as an important growth parameter to be followed. Patients with impending TIS are notorious for being unable to gain weight or in fact show progressive decline in body weight percentile. The accepted explanation is that the increased respiratory rate – the work of breathing – prevents weight gain as a symptom of established TIS. Recent studies (Skaggs et al. 2007) have demonstrated that patients treated with expandable chest wall or spine devices do in fact experience weight gain as a measurable indicator that the work of breathing has decreased, presumably due to the treatment. The failure to gain weight, or a declining weight percentile, in a patient with potential TIS must be included as a possible indication to begin growth/expansion treatment.

References Campbell Jr., R.M., Smith, M.D.: Thoracic insufficiency syndrome and exotic scoliosis. J. Bone Joint Surg. 89-A(suppl 1), 108–22 (2007) Campbell Jr., R.M., Smith, M.D., Mayes, T.C., et al.: The characteristics of thoracic insufficiency syndrome associated with fused ribs and congenital scoliosis. J. Bone Joint Surg. 85, 399–408 (2003) Dimeglio, A., Bonnel, F.: Le rachis en croissance. Springer, Paris (1990) Dubousset, J., Wicart, P., Pomero, V., et  al.: Thoracic scoliosis: exothoracic and endothoracic deformations and the spinal penetration index. Rev. Chir. Orthop. 88, 9 (2002) Emans, J.B., Ciarlo, M., Callahan, M., et al.: Prediction of thoracic dimensions and spine length based on individual pelvic dimensions in children and adolescents. Spine 30(24) : 2824–9 (2005) Gallogly, S., Smith, J.T., White, S.K., et al.: The volume of lung parenchyma as a function of age. Review of 1050 normal CT scans of the chest with three-dimensional volumetric reconstruction of the pulmonary system. Spine 29, 2061–6 (2004) Herring, J.A. (ed.): Tachdjian’s Pediatric Orthopaedics, p. 358. Saunders/Elsevier, Philadelphia (2008) McCarthy, R.E., McCullough, F.L., Luhmann, S.J., et al.: Shilla growth enhancing system for the treatment of scoliosis in children: greater than two year follow up. Paper #50. In: 43rd Scoliosis Research Society, Salt lake City, 10–13 Sept 2008 Skaggs, D.L., Albrektson, J., Wren, T.A., et  al.: Nutritional improvement following VEPTR ­surgery in children with thoracic insufficiency syndrome. Paper #44. In: 42nd Scoliosis Research Society, Edinburgh, 5–8 Sept 2007

 

Growth Modulation Techniques for Non-Idiopathic Early Onset Scoliosis

11

Eric J. Wall and Donita I. Bylski-Austrow

11.1  Introduction Growth modulation is a successful technique for the correction of limb deformity such as bowlegs, knock knees, and valgus ankles. It is one of the least invasive surgical procedures in pediatric orthopedics, involving much less blood loss, pain, and recovery time than the corresponding acute correction surgery via an osteotomy. Harnessing growth to prevent spine curve progression, or even to correct an existing deformity, might obviate spine fusion. The concept of scoliosis treatment by manipulation of the growth plate on the convex side of the curve has a long history, with methods ranging from biological to implantable devices (Fig. 11.1). Recent research has shown that spine growth can be selectively modified by compression. Like long bones, the vertebral growth plate structure is altered.

11.2  History The history of surgical spine growth alteration dates back nearly a century. In 1922, costotransversectomy with excavation of the vertebral bodies was reported to have resolved into an arthrodesis with obliteration of the epiphysis (MacLennan 1922). A canine model of scoliosis induction by injury to the epiphyseal cartilaginous plate on one side of a vertebra was described in 1939 (Haas 1939). The investigator concluded that such asymmetrical injuries might be successfully used as corrective procedures for spinal deformities. A similar injury model in goats led to the proposal that this form of treatment might be suitable for a child who had moderate curvature and several years of growth remaining (Bisgard 1934; Bisgard and Musselman 1940). The concept of deformity progression by ­asymmetrical

E.J. Wall (*) and D.I. Bylski-Austrow Department of Orthopedics, 3333 Burnet Avenue, Cincinnati, OH 45229-3026, USA e-mail: [email protected]; [email protected] M. Yazici (ed.), Non-Idiopathic Spine Deformities in Young Children, DOI: 10.1007/978-3-642-19417-7_11, © 2011 EFORT

133

134 

E.J. Wall and D.I. Bylski-Austrow

1

11

2

3

Growth plates

C

DIS

G r o w t h

I n h i b i t i o n

O v e r g r o w t h

Convex

Growth

Epiphysiosesis

Scoliosis guided growth

Fig. 11.1  Conceptual drawings of the effect of mechanical hemiepiphyseal implants on a growing, scoliotic spine. (1) Growing spine with moderate scoliosis. Growth is relatively inhibited on concavity and accelerated on convexity. (2) Implants added, which modify the growth of the two adjacent vertebral growth plates and span the disc. (3) Conceptually, scoliosis corrects with growth modulation

pressure on epiphyseal plates is well known to date back to the nineteenth century (Hueter, Volkmann, and Delpech (Mehlman et al. 1997)), and to have long been considered applicable to scoliosis by Volkmann (Arkin 1949; Arkin and Katz 1956). Risser called it “Hueter-Volkmann’s epiphyseal pressure rule” (Arkin 1949, Discussion). Following Blount and Clarke’s (1949) description of stapling for lower limb growth deformities in 1949, Nachlas and Borden (1951) proposed that “if selected growth control can make a straight spine grow curved, it might also make a curved spine grow straight.” Using a canine model, they produced, and then corrected, spinal curvatures using a stapling technique which introduced wire staples through the pedicles, reporting modest success. The staples spanned more than one disc. In the discussion of this work, LeMesurier reported using a technique similar to the earlier injury models in four young goats, with “complete failure” of the procedure. In this time period, a transthoracic approach to introduce wire staples into two contiguous vertebral bodies, across the intervertebral disc and two epiphyseal plates was reported (Smith et al. 1954) in patients, with no longer term follow-up. The notion that the scoliotic curve was self-propagating was articulated by Roaf (1960) as: “In scoliosis there is increased pressure on the concave aspect of the epiphyseal plates and diminished pressure on the convex aspects – that is, growth is inhibited on the

11  Growth Modulation Techniques for Non-Idiopathic Early Onset Scoliosis

135

concave side and unrestrained on the convex side.” He described a method of surgically removing a segment of annulus and about half of each epiphyseal cartilage in scoliosis patients. Inconsistent success was reported (Roaf 1963) with the hemilateral suppression of growth by excision of the intervertebral disc together with the bordering growth plates using a costo-transverse approach. Roaf later noted (1977) that stapling of the vertebral bodies had generally proved disappointing because the rate of growth was relatively slow compared to the lower limbs, staples in cancellous bone were not fully effective, and staples spanned a joint (the intervertebral disc) as well as two epiphyseal plates. In a review of studies on experimental scoliosis, MacEwen (1973) noted that stapling of the human spine was attempted in a few orthopedic centers, but that staple loosening occurred and were probably used in patients with curves that were too severe to expect any correction. The contemporary approach of epiphyseal stapling of the lower extremities was reviewed by Blount (1971). Staple insertion guidelines, including new materials and designs of staples, patient selection criteria, and indications and contraindications developed over the previous 20 years of experience were specified. Biological changes during closure of a stapled epiphyseal growth plate in rats were investigated (Ehrlich et  al. 1972). Small animal models of spine growth modification by external bracing (Wynarsky and Schultz 1987) and tethering (Sarwark et al. 1988; Smith and Dickson 1987) were reported. A review of growth modification methods in scoliosis, past and potential (Piggott 1987), listed a wide range of possibilities: stapling, epiphysiodesis of the vertebral bodies, posterior convex side fusion, costodesis, creation of a fibrous tether, excision of the convex side of the growth plates without fusion, compression of the convex side by means of a Dwyer-type apparatus without fusion, radiotherapeutic destruction of the convex side of the growth plate, and stimulation of growth on the concave side. Many others have reported related concepts and approaches more specifically for congenital spine deformities, early onset scoliosis and complex spine and life-threatening chest wall deformities, including biological and spine distraction methods, as recently reviewed (Akel and Yazici 2009). Spinal hemiepiphysiodesis has been used to describe the effect of a device that guides growth by constraining part of the vertebral growth plates, as evidenced by structural changes to the growth plates, as well as constraining at least some motion of a part of the intervertebral joint. The mechanism of action of growth modulation devices is relative restriction of longitudinal expansion of all structures encompassed by the device. Investigators have placed devices across the vertebral growth plate without spanning the disc in animals with boney endplates (Bylski-Austrow et al. 1998; Schmid et al. 2008), but it is not clear how this could be translated to human use because humans have cartilaginous endplates. The long history of spinal growth modulation is a reminder that the concept is challenging to reduce to clinical practice. Early pre-clinical and clinical reports show that many methods of spinal growth modulation have not worked. Some of the experimental studies, and the clinical experience with lower limb deformities, continue to reinforce the promise that it may work for some scoliosis patients under particular conditions. Careful consideration of spine growth (Dimeglio 2001), ­specific pathological structural changes, and biomechanical and mechanobiological principles (Stokes 2001) are essential to expand and improve the role of growth modulation in non-idiopathic scoliosis.

136 

11

E.J. Wall and D.I. Bylski-Austrow

11.3  Growth Modulation Non-fusion Devices for Non-Idiopathic Scoliosis In principle, if the growth of the convex side of a mild to moderate scoliosis curve may be slowed and/or the concave side stimulated, then future growth might be redirected into spine curve correction. Current fusion techniques such as anterior/posterior convex hemi-epiphysiodesis fusion are not particularly efficient at correcting scoliosis. This may be due to the relative inability to create a consistent convex fusion mass. Devices such as staples or tethers may allow for better scoliosis correction by targeting the convex vertebral growth plate without the need for an unpredictable fusion mass. Biologically, growth inhibition by compression is better understood and perhaps more efficient than growth acceleration by distraction. The potential for continued anterior growth after posterior spinal instrumentation is well-known (Dubousset et al. 1989; Kioschos et al. 1996). Further, anterior spinal overgrowth may be important in the pathomechanics of scoliosis itself (Chu et al. 2008; Day et al. 2008; Dickson et al. 1984; Goto et al. 2003; Gu et al. 2009; Guo et al. 2003; Stokes et al. 2006; Zhu et al. 2006). Current anterior spine growth modulation methods, staples and tethers, are compression-based systems that directly reduce anterior spine growth without fusion. Different methods of growth modification have different potential advantages and disadvantages compared to each other and compared to conventional fusion and instrumentation methods. With some techniques, scoliosis correction is gradual. This eliminates the risk of neurological injury that stems from the acute correction of scoliosis during standard fusion with instrumentation. Staple devices are typically much smaller than conventional scoliosis rods and screws. Therefore, the risk of accidental penetration into the spinal canal is lower than that with pedicle screws, hooks, wires and anterior bicortical screws. Staple devices have been implanted thoracoscopically in preclinical studies and in humans with small incisions that are largely hidden under the arm. Their insertion is simpler than thoracoscopic discectomy or thoracoscopic fusion and instrumentation procedures. Epiphysiodesis of the neurocentral synchondrosis (NCS) has been investigated as a method to correct scoliosis (Zhang and Sucato 2008). Unlike staples or tethers, this method does not span the disc, and may apply only to early onset scoliosis because the human NCS growth potential may be limited after the age of 6.

11.4  Growth Modulation Devices for Non-Idiopathic Early Onset Scoliosis: Recent Preclinical Studies After a series of pilot trials using different device designs, the authors designed an intervertebral implant specifically for spine growth modulation that repeatedly created a curve in a growing porcine model. Pilot studies that led to a successful anecdotal case were first presented in 1998 (Bylski-Austrow et al. 1998). The device then showed reproducible results in a follow up study (Wall et al. 2005). A curve of 20° (Fig. 11.2) was produced on average by 8 weeks after implantation in normal immature porcine spines, an inverse analog model of scoliosis treatment (Nachlas and Borden 1951). Histological analysis of the growth plate (Fig. 11.3) showed

11  Growth Modulation Techniques for Non-Idiopathic Early Onset Scoliosis

137

Fig. 11.2  Radio­ graphs of porcine thoracic spine (subject 3), anteroposterior view. Left: immediately after surgery. Right: after spine harvest, 8 weeks postoperative, Cobb angle 22°

Fig. 11.3  Photomicrographs of growth plate sample sections from stapled level T8-T9. At stapled level, the growth plate near the device (left) shows reduced hypertrophic zone height and cell size versus the side opposite the device (right)

138 

11

E.J. Wall and D.I. Bylski-Austrow

that the spinal implant narrowed the hypertrophic zone of the growth plate under the staple, which normalized with increasing distance from the staple toward the opposite side of the vertebra (Bylski-Austrow et al. 2009). This effect on the growth plate is similar to that described under growth-modulating knee staples (Farnum et al. 2000). No loosening, migration or plowing was noticed in a preclinical study in this rapidly growing animal model. Subsequent implant design changes for safety, clinical use, manufacturability, mechanical performance and improvements in surgical technique were made. The preclinical animal test was repeated in an independent laboratory under United States Food and Drug Administration Good Laboratory Practices (US FDA GLP). Curvatures were comparable to the first study, which verified the performance of the device design revised for clinical application to induce a spinal curve. To date, this device has not been implanted in humans with either idiopathic or non-idiopathic scoliosis. In related studies, microsensors (Glos et al. 2010) were implanted into the disc annulus in a porcine model at stapled and unstapled levels (Bylski-Austrow et al. 2006). Disc pressure fluctuations during animal activity and rest remained within physiologic levels. In in vitro biomechanical studies conducted in the authors’ laboratory, published in abstract form only to date, peak stresses in the disc annulus on both ipsilateral and contralateral sides were dampened by approximately 20% compared the motion segment prior to instrumentation. Conceivably, this type of implant may shield the disc from potentially damaging compressive over-loading. Other investigators have used shape memory alloy (SMA) staples fabricated from nitinol for spine growth modulation. These staples undergo a phase change when removed from an ice water bath and warmed up to body temperature during implantation into the spine. During this phase change, the tines of the staple move together. Biomechanical tests showed that the staples restrict motion, but not to the extent of fusion-promoting instrumentation (Puttlitz et  al. 2007). These devices have shown inconsistent results in preclinical studies using a rapidly growing animal model. Initially favorable results (Braun et  al. 2004, 2006b) in correcting an animal model of scoliosis with the shape memory staple were not validated in later studies by the same authors in comparison to a ligament tether device (Braun et al. 2006a). SMA staples did not appear to cause disc degeneration as measured by disc hydration and MRI. Some changes have been reported in cell density, apoptosis and endplate structure (Hunt et al. 2010). Tethers are devices in which screws or bone anchors are placed into the mid-vertebral bodies (Braun et al. 2006a; Newton et al. 2005, 2008), and are linked together by a cable or a polymer band on the convex side of the curve. Growth is limited under the tether, whereas growth on the contralateral side is less impeded, potentially allowing for curve correction. Although a tether device showed a high rate of plowing, migration and breakage in a rapidly growing calf model, tether device stability and growth modulation performance was demonstrated in a mini-pig model which has a growth rate that more closely approximates that of a human adolescent (Newton et al. 2008). Disc health was qualitatively maintained under this tether device based on MR images, although quantitative changes in disc height and water content were observed (Newton et al. 2008). Tether devices are more complex to implant than staple devices, which may make them less suitable for thoracoscopic surgical techniques. Because tether bone screws are placed centrally in the vertebrae, the segmental artery in the mid-body must be sacrificed at each level. Most tethers use bicortical vertebral

11  Growth Modulation Techniques for Non-Idiopathic Early Onset Scoliosis

139

body screws and bone staples to mitigate the risk of pull-out and plowing, as the forces and moments that cause these displacements are increased at the ends of any spinal device linked over multiple levels. Recent research has produced quantifiable evidence of the forces that alter bone growth. The forces that result in disc injury (Iatridis et al. 1999; Lotz and Chin 2000; Maclean et al. 2004; Walsh and Lotz 2004) are likely more than an order of magnitude greater than the forces that alter growth. The force magnitude that stops growth, as expressed as the static equivalent load exerted at the joint centerline, has been reported to be 0.5 kN, or 105– 125% of the normal body weight of adolescents, which corresponds to a compressive stress on the order of 1 MPa (Bylski-Austrow et al. 2001). Further quantification of the forces and stresses on discs and growth plates and deeper understanding of the biological processes are required to determine if growth may be appropriately guided without undue deleterious side effects on the intervertebral joint (Alini et al. 2008; Forriol and Shapiro 2005; Villemure and Stokes 2009).

11.5  Predicting Progression Radiographic prognostic techniques have improved, and genetic tests are evolving for idiopathic (Dimeglio et al. 2005; Sanders et al. 2008) and non-idiopathic scoliosis. These may enable a clinician to determine which children are most likely to require deformity correction surgery despite perhaps several years of wearing a brace. Unfortunately, non-idiopathic scoliosis progression is difficult to predict accurately, especially in congenital scoliosis. Frequent follow-up is needed to determine which small curves will become large curves. The effectiveness of braces at slowing the progression of non-idiopathic scoliosis is unknown due to a lack of controlled studies.

11.6  Growth Modulation Devices for Non-Idiopathic Scoliosis: Human Studies Shape memory staples have been in “physician directed” clinical use for the treatment of scoliosis in growing children with non-idiopathic and idiopathic curves. Eleven children were studied with non-adolescent idiopathic scoliosis that underwent open anterior vertebral body stapling (O’Leary et  al. 2006). This group included the diagnosis of Marfan syndrome, early onset scoliosis, neuromuscular scoliosis, spinal cord injury, and myelomeningocele. All patients had an open tri-radiate cartilage, and had an average pre-operative curve of 68°. Immediate postoperative correction down to an average of 45° was achieved, which subsequently increased to 69° at a mean follow-up of 22  months postoperatively. There were no safety complications, but 5/11 patients required additional surgery due to progression. The authors suggested that this high rate of failure was due to the high curve magnitude at the time of stapling with no preoperative curve less than 44°. It was ­hypothesized

140 

11

E.J. Wall and D.I. Bylski-Austrow

that the biologic compression on the concave side of a severe curve would not allow enough corrective growth once the staples were placed on convex side. In another series of six patients with non-adolescent idiopathic scoliosis that underwent stapling, four out six curves stabilized at 2 years follow-up (Betz et al. 2010). Two patients had partial dislodgement of their devices, requiring reoperation for replacement. Specific ages, staple type, and curve magnitude were not reported in this small group. In comparison to the high failure rate of SMA staples in large non-idiopathic curves, 79% success has been reported with SMA staples for pre-operative thoracic idiopathic curves £35° (Betz et al. 2010; Crawford and Lenke 2010; Guille et al. 2007). Better results seemed to correlate with curves that reduced to £20° on bending films. Success was defined as <10° Cobb angle progression from the initial pre-operative curve. Even in idiopathic scoliosis, a 75% failure rate was reported for preoperative Cobb angles >35° with a SMA staple. However, at least some failures may be more related to implant design factors than to the growth modulation concept. It is not clear if the primary correction mechanism of SMA staples is by actual growth modulation, rather than from the initial correction that may result from placing the device in an anesthetized patient while applying manual corrective forces to the spine, or other possible mechanisms. Tether devices can also impart some immediate angular correction by tensioning the tether. Tether devices have been implanted in a few humans with idiopathic scoliosis, with one case report published on a patient followed for 4  years (Hutton et  al. 1998). There is no reported data for tether devices in the treatment of non-idiopathic scoliosis. Growth modulation via convex hemiepiphysiodesis fusion has been successful in stopping or mildly reversing progressive congenital scoliosis, particularly in children under the age of 10 (Andrew and Piggott 1985; Ginsburg et al. 2007; Keller et al. 1994; King et al. 1992; Marks et al. 1995, 1996; Winter 1981; Winter et al. 1988). This can be reasonably effective in congenital scoliosis associated with diastematomyelia (Uzumcugil et al. 2003, 2004) or associated with sagittal plane deformity such as hyper or hypo kyphosis (Cil et al. 2004; Kieffer and Dubousset 1994). Non-idiopathic dysplastic scoliosis associated with chondrodysplasia punctata did not respond well to hemiepiphysiodesis fusion (Mason et al. 2002). Hemivertebrae resection and hemiepiphysiodesis were found to give equivalent long term results in a large multicenter study on congenital scoliosis (Louis et al. 2010). In contrast to the modest correction or stabilization of congenital scoliosis, hemivertebrae excision with pedicle screw fixation can give more dramatic and immediate correction. Twenty-eight children with a mean age of 3 years 4 months after this procedure and at 3.5 years follow up showed curve correction from 45° down to 13° (Ruf and Harms 2003). Potential problems with growth modulation may be discerned from reported preclinical and clinical studies to date. Convex fusion for hemiepiphysiodesis appears best suited to children with moderate curves with abundant future growth. It is a fairly invasive, but safe surgery with a very low reported incidence of neurological injury. True curve correction is seen in a minority of cases, and it fails about 10–20% of the time, probably due the unpredictable development of a convex fusion mass. Non-fusion growth modulation with a well designed and tested device may be more effective at curve correction than a convex hemifusion. However non-fusion devices can suffer breakage and migration. This could necessitate additional surgery, and in the case of failure to control or correct the scoliosis, a standard fusion surgery may be needed. Theoretically, insertion of very effective growth

11  Growth Modulation Techniques for Non-Idiopathic Early Onset Scoliosis

141

modulating devices in young children with mild curves could lead to the development of a curve in the opposite direction (overcorrection), similar to that observed with knee and ankle hemiepiphysiodesis. The ease and safety of device removal are important considerations. Compensatory curves above and below the instrumented levels might develop. This may necessitate extending the levels of the growth modulating device. Even though the implantation of these devices is less surgically extensive than an anterior or posterior spinal convex fusion procedure, surgical complications such as bleeding, pneumothorax, pleural effusion, infection, breakage, migration, and failure to prevent curve progression remain risks (Guille et al. 2007).

11.7  Conclusion Growth modulation remains a compelling concept that has the potential to spare children at high risk of non-idiopathic deformity progression from ineffective brace wear and a major fusion surgery. Young children with congenital scoliosis have shown good, but inconsistent results with convex hemi-fusion. Prospective clinical research under controlled conditions is needed for non-fusion devices due to the limited information currently available on its safety and performance. Obtaining regulatory and ethics authority approval to study new and innovative pediatric devices are not easy. Despite many obstacles and complexities, clear progress has been made in the last two decades, and much promising work is ongoing. In this active environment of life sciences technology advancement, growth modulation may yet become a standard of care for a subgroup of children with non-idiopathic scoliosis.

References Akel, I., Yazici, M.: Growth modulation in the management of growing spine deformities. Current concept review. J. Child. Orthop. 3, 1–9 (2009) Alini, M., Eisenstein, S.M., Ito, K., et al.: Are animal models useful for studying human disc disorders/degeneration? Eur. Spine J. 17(1), 2–19 (2008) Andrew, T., Piggott, H.: Growth arrest for progressive scoliosis. Combined anterior and posterior fusion of the convexity. J. Bone Joint Surg. 67-B, 193–197 (1985) Arkin, A.M.: The mechanism of the structural changes in scoliosis. J. Bone Joint Surg. Am. 31A(3), 519–528 (1949) Arkin, A.M., Katz, J.F.: The effects of pressure on epiphyseal growth; the mechanism of plasticity of growing bone. J. Bone Joint Surg. Am. 38-A(5), 1056–1076 (1956) Betz, R.B., Ranade, A., Samdani, A.F., et al.: Vertebral body stapling: a fusionless treatment option for a growing child with moderate idiopathic scoliosis. Spine 35(2), 169–176 (2010) Bisgard, J.D.: Experimental thoracogenic scoliosis. J. Thorac. Surg. 4, 435–442 (1934) Bisgard, J.D., Musselman, M.M.: Scoliosis: its experimental production and growth correction: growth and fusion of vertebral bodies. Surg. Gynecol. Obstet. 70, 1029–1036 (1940) Blount, W.P.: A mature look at epiphyseal stapling. Clin. Orthop. Relat. Res. 77, 158–163 (1971) Blount, W.P., Clarke, G.R.: Control of bone growth by epiphyseal stapling. A preliminary report. J. Bone Joint Surg. Am. 31-A, 464–478 (1949)

142 

11

E.J. Wall and D.I. Bylski-Austrow

Braun, J.T., Akyuz, E., Udall, H., et al.: Three dimensional analysis of 2 fusionless scoliosis treatments: a flexible ligament tether versus a rigid shape memory alloy staple. Spine 31(3), 262–268 (2006a) Braun, J.T., Hoffman, M., Akyuz, E., et al.: Mechanical modulation of vertebral growth in the fusionless treatment of progressive scoliosis in an experimental model. Spine 31(12), 1314–1320 (2006b) Braun, J.T., Ogilvie, J.W., Akyuz, E., et al.: Fusionless scoliosis correction using a shape memory alloy staple in the anterior thoracic spine of the immature goat. Spine 29(18), 1980–1989 (2004) Bylski-Austrow, D.I., Wall, E.J., Glos, D.L., et al.: Spinal hemiepiphysiodesis decreases size of vertebral growth plate hypertrophic zone and cells. J. Bone Joint Surg. Am. 91, 584–593 (2009) Bylski-Austrow, D.I., Glos, D.L., Sauser, F.E., et al.: Bilateral intra-annular spinal compressive stresses in  vivo. In: Uyttendaele D., Dangerfield P.H. (eds.) 6th Biennial Meeting of the International Research Society of Spinal Deformities Gent Belgium, June 2006. Published in Research into Spinal Deformities, vol. 2. IOS Press, Washington DC (2006) Bylski-Austrow, D.I., Wall, E.J., Kolata, R.J., et al.: Endoscopic nonfusion spinal hemiepiphysiodesis. Preliminary studies in a porcine model. In: Stokes I.A.F., Dangerfield P.H. (eds.) 2nd Biannual Meeting of the International Research Society for Spinal Deformities, Burlington, Vermont, June 27–July 1, 1998. Published in Research into Spinal Deformities, vol. 2. IOS Press, Washington DC (1999) Bylski-Austrow, D.I., Wall, E.J., Rupert, M.P., et al.: Growth plate forces in adolescent human knees: radiographic and mechanical study of epiphyseal staples. J. Pediatr. Orthop. 21, 817–823 (2001) Chu, W.C., Man, G.C., Lam, W.W., et al.: Morphological and functional electrophysiological evidence of relative spinal cord tethering in adolescent idiopathic scoliosis. Spine 31, 673–680 (2008) Cil, A., Yazici, M., Alanay, A., et al.: The course of sagittal plane abnormality in the patients with congenital scoliosis managed with convex growth arrest. Spine 29(5), 547–552 (2004). discussion 552–553 Crawford, C.H., Lenke, L.G.: Growth modulation by means of anterior tethering resulting in progressive correction of juvenile idiopathic scoliosis: a case report. J. Bone Joint Surg. Am. 92, 202–209 (2010) Day, G., Frawley, K., Phillips, G., et al.: The vertebral body growth plate in scoliosis: a primary disturbance of growth? Scoliosis 3, 3 (2008) Dickson, R.A., Lawton, J.O., Archer, I.A., et al.: The pathogenesis of idiopathic scoliosis. Biplanar spinal asymmetry. J. Bone Joint Surg. Br. 66-B, 8–15 (1984) Dimeglio, A.: Growth in pediatric orthopaedics. J. Pediatr. Orthop. 21(4), 549–555 (2001) Dimeglio, A., Charles, Y.P., Daures, J.P., et al.: Accuracy of the Sauvegrain method in determining skeletal age during puberty. J. Bone Joint Surg. Am. 87-A, 1689–1696 (2005) Dubousset, J., Herring, J.A., Shufflebarger, H.: The crankshaft phenomenon. J. Pediatr. Orthop. 9, 541–550 (1989) Ehrlich, M.G., Mankin, H.J., Treadwell, B.V.: Biochemical and physiological events during closure of the stapled distal femoral epiphyseal plate in rats. J. Bone Joint Surg. Am. 54-A, 309–322 (1972) Farnum, C.E., Nixon, A., Lee, A.O., et al.: Quantitative three-dimensional analysis of chondrocytic kinetic responses to short-term stapling of the rat proximal tibial growth plate. Cells Tissues Organs 167(4), 247–258 (2000) Forriol, F., Shapiro, F.: Bone development: interaction of molecular components and biophysics. Clin. Orthop. Relat. Res. 432, 14–33 (2005) Ginsburg, G., Mulconrey, D.S., Browdy, J.: Transpedicular hemiepiphysiodesis and posterior instrumentation as a treatment for congenital scoliosis. J. Pediatr. Orthop. 27(4), 387–391 (2007) Glos, D.L., Sauser, F.E., Papautsky, I., et  al.: Implantable MEMS compressive stress sensors: design, fabrication and calibration with application to the disc annulus. J. Biomech. 43(11), 2244–2248 (2010) Goto, M., Kawakami, N., Azegami, H., et al.: Buckling and bone modeling as factors in the development of idiopathic scoliosis. Spine 28(4), 364–370 (2003). discussion 371

11  Growth Modulation Techniques for Non-Idiopathic Early Onset Scoliosis

143

Gu, S.X., Wang, C.F., Zhao, Y.C., et al.: Abnormal ossification as a cause the progression of adolescent idiopathic scoliosis. Med. Hypotheses 72(4), 416–417 (2009) Guille, J.T., D’Andrea, L.P., Betz, R.R.: Fusionless treatment of scoliosis. Orthop. Clin. North Am. 38(4), 541–545 (2007). vii. Review Guo, X., Chau, W.W., Chan, Y.L., et al.: Relative anterior spinal overgrowth in adolescent idiopathic scoliosis. Results of disproportionate endochondral-membranous bone growth. J. Bone Joint Surg. Br. 85(7), 1026–1031 (2003) Haas, S.L.: Experimental production of scoliosis. J. Bone Joint Surg. 21, 963–968 (1939) Hunt, K.J., Braun, J.T., Christensen, B.A.: The effect of two clinically relevant fusionless scoliosis implant strategies on the health of the intervertebral disc. Spine 35(4), 371–377 (2010) Hutton, W.C., Toribatake, Y., Elmer, W.A., et al.: The effect of compressive force applied to intervertebral disc in vivo. Spine 23(23), 2524–2537 (1998) Iatridis, J.C., Mente, P.L., Stokes, I.A., et al.: Compression-induced changes in intervertebral disc properties in a rat tail model. Spine 24, 996–1002 (1999) Keller, P.M., Lindseth, R.E., DeRosa, G.P.: Progressive congenital scoliosis treatment using a transpedicular anterior and posterior convex hemiepiphysiodesis and hemiarthrodesis. A preliminary report. Spine 19(17), 1933–1939 (1994) Kieffer, J., Dubousset, J.: Combined anterior and posterior convex epiphysiodesis for progressive congenital scoliosis in children aged < or = 5 years. Eur. Spine J. 3(2), 120–125 (1994) King, A.G., MacEwen, G.D., Bose, W.J.: Transpedicular convex anterior hemiepiphysiodesis and posterior arthrodesis for progressive congenital scoliosis. Spine 17(8 Suppl), S291–S294 (1992) Kioschos, H.C., Asher, M.A., Lark, R.G., et  al.: Overpowering the crankshaft mechanism: the effect of posterior spinal fusion with and without stiff transpedicular fixation on anterior spinal column growth in immature canines. Spine 21(10), 1168–1173 (1996) Lotz, J.C., Chin, J.R.: Intervertebral disc cell death is dependent on the magnitude and duration of spinal loading. Spine 25(12), 1477–1483 (2000) Louis, M.L., Gennari, J.M., Loundou, A.D., et al.: Congenital scoliosis: a frontal plane evaluation of 251 operated patients 14 years old or older at follow-up. Orthop. Traumatol. Surg. Res. 7, 741–747 (2010) MacEwen, G.D.: Experimental scoliosis. Clin. Orthop. Relat. Res. 93, 69–74 (1973) Maclean, J.J., Lee, C.R., Alini, M., et al.: Anabolic and catabolic mRNA levels of the intervertebral disc vary with the magnitude and frequency of in vivo dynamic compression. J. Orthop. Res. 22(22), 1193–1200 (2004) MacLennan, A.: Scoliosis. Br. Med. J. 2, 864–866 (1922) Marks, D.S., Iqbal, M.J., Thompson, A.G., et al.: Convex spinal epiphysiodesis in the management of progressive infantile idiopathic scoliosis. Spine 21, 1884–1888 (1996) Marks, D.S., Sayampanathan, S.R., Thompson, A.G., et al.: Long-term results of convex epiphysiodesis for congenital scoliosis. Eur. Spine J. 4(5), 296–301 (1995) Mason, D.E., Sanders, J.O., MacKenzie, W.G., et  al.: Spinal deformity in chondrodysplasia punctata. Spine 27(18), 1995–2002 (2002) Mehlman, C.T., Araghi, A., Roy, D.R.: Hyphenated history: the Hueter-Volkmann law. Am. J. Orthop. 26(11), 798–800 (1997) Nachlas, I.W., Borden, J.N.: The cure of experimental scoliosis by directed growth control. J. Bone Joint Surg. Am. 33(A:1), 24–34 (1951) Newton, P.O., Farnsworth, C.L., Faro, F.D., et al.: Spinal growth modulation with an anterolateral flexible tether in an immature bovine model: disc health and motion preservation. Spine 33(7), 724–733 (2008) Newton, P.O., Faro, F.D., Farnsworth, C.L., et al.: Multilevel spinal growth modulation with an anterolateral flexible tether in an immature bovine model. Spine 30(23), 2608–2613 (2005) O’Leary, P., Sturm, P., Hammerberg, K., et al.: Convex hemiepiphysiodesis: the limits of vertebral stapling (Abst). Presented at International Meeting for Advanced Spinal Techniques, July 2006. Athens, Greece (2006)

144 

11

E.J. Wall and D.I. Bylski-Austrow

Piggott, H.: Growth modification in the treatment of scoliosis. Orthopedics 10(6), 945–952 (1987) Puttlitz, C.M., Masaru, F., Barkley, A., et  al.: A biomechanical assessment of thoracic spine stapling. Spine 32(7), 766–771 (2007) Roaf, R.: Vertebral growth and its mechanical control. J. Bone Joint Surg. Br. 42-B, 40–59 (1960) Roaf, R.: The treatment of progressive scoliosis by unilateral growth-arrest. J. Bone Joint Surg. Br. 45-B, 637–651 (1963) Roaf, R.: Growth arrest procedures. In: Spinal Deformities, pp. 219–221. JB Lippincott Co, Philadelphia (1977) Ruf, M., Harms, J.: Posterior hemivertebra resection with transpedicular instrumentation: early correction in children aged 1 to 6 years. Spine 28(18), 2132–2138 (2003) Sanders, J.O., Khoury, J.G., Kishan, S., et al.: Predicting scoliosis progression from skeletal maturity: a simplified classification during adolescence. J. Bone Joint Surg. Am. 90(3), 540–553 (2008) Sarwark, J.F., Dabney, K.W., Salzman, S.K., et al.: Experimental scoliosis in the rat. I. Methodology, anatomic features and neurologic characterization. Spine 13(5), 466–471 (1988) Schmid, E.C., Aubin, C.E., Moreau, A., et al.: A novel fusionless vertebral physeal device inducing spinal growth modulation for the correction of spinal deformities. Eur. Spine J. 17(10), 1329–1335 (2008) Smith, A.D., Von Lackum, W.H., Wylie, R.: An operation for stapling vertebral bodies in congenital scoliosis. J. Bone Joint Surg. Am. 6-A, 342–347 (1954) Smith, R.M., Dickson, R.A.: Experimental structural scoliosis. J. Bone Joint Surg. Br. 69-B, 576–581 (1987) Stokes, I.A., Burwell, R.G., Dangerfield, P.H.: Biomechanical spinal growth modulation and progressive adolescent scoliosis – a test of the ‘vicious cycle’ pathogenetic hypothesis: summary of an electronic focus group debate of the IBSE. Scoliosis 1, 16 (2006) Stokes, I.A.F.: Spinal biomechanics. In: Weinstein, S.L. (ed.) The Pediatric Spine: Principles and Practice, 2nd edn, pp. 57–71. Lippincott Williams & Wilkins, Philadelphia (2001) Uzumcugil, A., Cil, A., Yazici, M., et al.: The efficacy of convex hemiepiphysiodesis in patients with iatrogenic posterior element deficiency resulting from diastematomyelia excision. Spine 28(8), 799–805 (2003) Uzumcugil, A., Cil, A., Yazici, M., et  al.: Convex growth arrest in the treatment of congenital spinal deformities, revisited. J. Pediatr. Orthop. 24(6), 658–666 (2004) Villemure, I., Stokes, I.A.: Growth plate mechanics and mechanobiology. A survey of present understanding. J. Biomech. 42(12), 1793–1803 (2009) Wall, E.J., Bylski-Austrow, D.I., Kolata, R.J., et al.: Endoscopic mechanical spinal hemiepiphysiodesis modifies spine growth. Spine 30(10), 1148–1153 (2005) Walsh, A.J.L., Lotz, J.C.: Biological response of the intervertebral disc to dynamic loading. J. Biomech. 37, 329–337 (2004) Winter, R.B.: Convex anterior and posterior hemiarthrodesis and hemiepiphyseodesis in young children with progressive congenital scoliosis. J. Pediatr. Orthop. 1(4), 361–366 (1981) Winter, R.B., Lonstein, J.E., Denis, F., et  al.: Convex growth arrest for progressive congenital scoliosis due to hemivertebrae. J. Pediatr. Orthop. 8(6), 633–638 (1988) Wynarsky, G., Schultz, A.: Effects of age and sex on the external induction of scoliosis in rats. Spine 12(10), 974–977 (1987) Zhang, H., Sucato, D.J.: Unilateral pedicle screw epiphysiodesis of the neurocentral synchondrosis. Production of idiopathic-like scoliosis in an immature animal model. J. Bone Joint Surg. Am. 90(11), 2460–2469 (2008) Zhu, F., Qiu, Y., Yeung, H.Y., et  al.: Histomorphometric study of the spinal growth plates in idiopathic scoliosis and congenital scoliosis. Pediatr. Int. 48(6), 591–598 (2006)

Instrumentation in the Childhood Spinal Deformities: Challenges, Problems, Limitations, and Solutions

12

Muharrem Yazici and Z. Deniz Olgun

Attempts at surgical intervention for spinal deformities have been performed throughout centuries, yet the commencement of modern spinal surgery took place in the 1960s. Not only did Paul Harrington design a device to be used in the treatment of several spinal disorders, he also broke the taboo on spinal surgery and put an end to the “untouchable” status of the vertebral column. The courage of Harrington paved the way for the design and application of modern spinal implants. The original Harrington implant was not suitable for young children dimensionwise. During pre-Harrington years, wires were used to fix posterior elements on one or more levels. However, pioneered by Luque, posterior instrumentation via sublaminar wires started to be applied in 1970s. It would not be wrong to accept the Luque system – which is suitable for children of all age groups as long as posterior elements of their vertebrae are intact – as the true predecessor of modern spinal instrumentation for small children. The development of the pedicle screw as an instrumentation method in spinal surgery in the late 1980s and especially through the 1990s has been a genuine breakthrough in this field. Thanks to this method, it has been possible to purchase and manipulate vertebrae more strongly and correct deformities more competently. In surgical interventions where pedicle screws are employed, it is also possible to keep the instrumentation confined to a minimum of levels and save motion in more spinal segments. Pedicle screw fixation is the gold standard in today’s practice of adult spinal surgery. Even though the development of screws has substantially decreased implant-related problems for adult patients, there are still many unsolved problems regarding pediatric spinal instrumentation. This paper discusses the challenges of childhood spinal instrumentation and offers updated solutions.

M. Yazici (*) and Z.D. Olgun Department of Orthopedics, Hacettepe University, Faculty of Medicine, Sihhiye, Ankara 06100, Turkey e-mail: [email protected]; [email protected]

M. Yazici (ed.), Non-Idiopathic Spine Deformities in Young Children, DOI: 10.1007/978-3-642-19417-7_12, © 2011 EFORT

145

146

12

M. Yazici and D.Z. Olgun

Problems: 1. Profile problems 2. Purchase problems 3. Growth-related problems 4. Material-related problems

12.1  Profile Problems Instruments commonly used today in posterior spinal surgery can be classified in three categories. 1. Hooks (a) Infra- or supralaminar hooks (b) Transverse process hooks (c) Hook-end plate screw combinations 2. Wires (or polyester band) (a) Sublaminar wires (b) Spinous process wires (c) Transverse process wires 3. Pedicle screws The profile of spinal surgery implants presents two main problems: (a) The height of the implant profile causes difficulties during skin closure or may lead to skin problems in the early post-op period. (b) The shape of the implant is not suitable for the anatomy of the vertebral region it is applied to or it may create risk of spinal cord compression by taking up space inside the spinal canal. As Harrington hooks were quite bulky implants originally, they were quite unsuitable for young children. This problem has been eliminated with recently developed hooks with a lower profile. Almost all of pediatric spinal sets on the market today contain specifically designed low-profile laminar or transverse process hooks along with hooks compatible with lamina or facet joint anatomy, and canal intrusion for supra- or infralaminar applications has been minimized. Today, in cases where hook usage is indicated, implant profile has ceased to be a problem. Wires used to fix posterior elements are the most advantageous implants with respect to profile. Wiring does not present safety issues as long as it is performed carefully. The efficacy of sublaminar and spinous process wiring, especially in neuromuscular deformity correction and apex translation of idiopathic deformities, has been clearly documented in numerous studies (Burton et al. 2005). Some biomechanical advantages of sublaminar wiring are still extant: The cortical structure of the laminas plays a key role in the preference

12  Instrumentation in the Childhood Spinal Deformities: Challenges, Problems, Limitations, and Solutions

147

of sublaminar wiring, especially in osteoporotic spines (Butler et al. 1994). Likewise, in early childhood, when the vertebral body contains substantial cartilage, fixation via the ossified laminas may well present mechanical advantages. There is no study on the efficacy and dependability of transverse process wiring – a technique developed to increase the force to be transferred to the spine by elongating the moment arm during the translation ­maneuver and to avoid intracanal surgery (Erel et  al. 2003) in young children. Implant insufficiency, caused by laminar fractures because of the sublaminar wires unfortunately remains a frequently experienced complication. In order to minimize this risk, the use of polyester bands – instead of stainless wire – is recommended. The preliminary results of these practices in the adolescent age group are satisfactory (Mazda et al. 2009). However, no clinical data are available on the applicability of these polyester bands in small children. The clamps connecting these bands to the rod are smooth implants of quite a low profile. Therefore, no additional skin problems should occur. On the other hand, the implant takes up more room in the canal compared to the wire. The importance of this canal intrusion for a young child remains unknown. Also in the long run, the biological reaction created by the polyester contacting the spinal cord is another topic that requires further research. The first version of the pedicle screw clearly was a revolutionary tool for modern spinal surgery; yet even they were not suitable for young children because of their size and connections with rods. Development of miniature sets to be used in pediatric surgery eliminated the profile problem in terms of connections. However, the compatibility between pedicle diameter and screw width is still an unsolved problem. The minuteness of the inner diameters of the upper lumbar (Senaran et al. 2002) and especially the thoracic pedicles (Zindrick et al. 2000), presents a disadvantage for the suitableness of commercially available pedicle screws. Nevertheless, screws are being widely used especially in lumbar area in the pediatric age group (Fig. 12.1). In clinical series, the neurological complication rate related to pedicle screws inserted in childhood is reported to be less than 1%. Also, it is emphasized that these were minor and mostly temporary complications (Akbarnia et al. 1996; Brown et al. 1998). Yet for thoracolumbar segments of very young children and thoracic segments of the juvenile age group, the problem with diameter still remains unsolved. There are three ways to overcome the problem of mismatch between screw and pedicle diameters: 1. Decreasing the screw diameter: Today manufacturing screws with very small diameters is technologically possible. However, it has been shown that there is a linear correlation between the diameter of the screw and its biomechanical power (Kwok et al. 1996). Hence, adapting the screw diameter to the pedicle does not provide a solution as extremely thin screws cannot transmit the necessary loads to the spine. 2. Enlarging the pedicle diameter: The plasticity of the bone structure is a recognized characteristic of the pediatric age group. It is known that under pressure the bones of the appendicular skeleton may show plastic deformation while preserving their macroscopic integrity. For many years, assuming that plastic deformation occurs in pediatric pedicles also, surgeons did not refrain from using screws larger than the pedicle diameter and dilating the pedicle with a probe or tap. However, until recently this method was not supported by any scientific evidence. For the first time, Rinella et  al. have shown that the pedicles of an immature cadaver bone can be dilated in vitro (Rinella et al. 2004). Later, in an experimental study performed on immature pigs, where the

148

M. Yazici and D.Z. Olgun

12

Fig. 12.1  Six and half year old boy with a hemivertebra at thoracic level (a). He presented with paraparesia and was treated with posterior-only hemivertebrectomy and instrumented fusion using pedicle screws (b)

authors used dilators designed specifically for this purpose, Yazici et al. (2006) managed to widen the inner diameter by 34% and the outer diameter by 15% of the pedicles without causing fracture. However, in this in  vitro study, it should be noted that the pullout strengths of the screws placed in expanded pedicles were significantly lower compared to non-expanded pedicles. The same authors later repeated the study in vivo and followed these immature pigs for 4 months (Yilmaz et al. 2008). In this new study, they demonstrated that there is no significant difference between the expanded and nonexpanded pedicles. The difference between the two studies is explained with the endurance-increasing effect of the new bone generated in the remodeling in the expanded pedicle that increases the strength of the screw. Evaluating these two studies together,

12  Instrumentation in the Childhood Spinal Deformities: Challenges, Problems, Limitations, and Solutions

149

one may conclude that pediatric pedicles can be enlarged during and made more ­suitable for placing screws of wider diameters during surgery. Moreover, one may deduce that an external support is needed for a while to avoid implant insufficiency in the early postoperative term. While this attribute of pediatric pedicles has been demonstrated in experimental models, it needs to be tested further in clinical practice for efficiency and reliability. 3. Redirecting the screw through a non-pedicle route to the vertebral body (in–out–in technique): The widespread use of the thoracic pedicle screw and its placement especially in apical areas where trans-pedicular screw placement is challenging and pedicle anatomy is distorted inspired surgeons to seek out new methods. One of the methods developed with this perspective is the extra-pedicular screw placement with in–out–in technique. The biomechanical strength of the screws placed with this method has been tested on adult spines. It was concluded that this method was significantly weaker in comparison with that of screws placed using classical methods (White et al. 2006). Yet, researchers argue that this weakness would not hamper the clinical applications in adult patients. They advocate that the method is clinically applicable during multileveled screwing. However, one should bear in mind that the in–out–in technique has not yet been tested for reliability and efficacy on pediatric spines. Along with the controversial matters regarding the biomechanics of the method, the fact that the extra-pedicular screw led to pneumothorax in a child is a serious complication and needs considerable attention (Viswanathan et al. 2008). The idea of applying the screw on non-pedicle structures has been on surgeons’ minds for many years. It has been shown that placing screws in transverse processes is not a good alternative – except for T1 – in adults (Heller et al. 1999). It would be unrealistic to expect this technique with its lack of promising results in adults be an alternative treatment in children. Lately, published case series are encouraging in the mention of the possibility of a strong fixation with intralaminar screw placement in the C2 vertebra (Wang 2007). Meanwhile, the results of a similar instrumentation in the pediatric age group – in terms of profile and purchase strength – need further study. It should be kept in mind that even in the adult group the vertebral laminas – excluding C2 – lack the size to house a screw.

12.2  Purchase Problems There are scarcely any studies on the biomechanical properties of the pediatric spine. Almost all of these studies have been conducted on immature animals and the results were tried to be extrapolated to the human spine. Obviously, such an approach has significant limitations. Determining the biomechanical characteristics of the pediatric spine and illuminating the transformations that take place in its deformed form are going to be the most popular research topics in the near future. Usually, there is a high success rate in cases where instrumentation is used together with fusion regardless of the implant type (wire, hook, or screw) used. The risk of implant

150

12

M. Yazici and D.Z. Olgun

failure can be significantly decreased with the use of external support in the postoperative period. However, implant failure is highly likely in non-fusion instrumentation, the most frequently preferred method for this age group. Mahar et al. (2008) have tested various instrument configurations on non-fusion instrumentation models and demonstrated that the strongest foundation was obtained with screw–screw combinations. Even if biomechanical durability increases in the hook–hook combination when it is supported with a cross-link, its strength is not as great as in the screw–screw version. While implant failure usually appears in the bone–implant interface (laminar fracture and hook dislodgement) in hook– hook combinations, it takes place at the vertebral body in screw–screw combinations. Undoubtedly, the dislodgment of the hook is an undesirable incident and needs revision. However, it usually does not lead to serious neurological problems. On the other hand, implant failure leading to a fracture of the vertebral body presents the risk of severe neurological deficit, especially in the case of convergent placement of the screws. Alanay et al. (2003) reported a late neurological deficit related to the screw pullout in case with pediatric kyphosis corrected with a pedicle screw construct at the upper end of instrumentation. Despite this anecdotal information, screw use in non-fusion instrumentation is becoming widely employed because of the advantages of pedicle screw fixation (Ahmadiadli et al. 2008) (Fig. 12.2). A safer application method in terms of pullout, without compromising the screw’s advantages is to support screw fixation in the upper thoracic area with sublaminar wires (Charles Johnston, personal communication) (Fig. 12.3). However, a study on the efficacy and reliability of this method is yet to be published. In cases like osteoporosis that threaten the quality of screw purchase, fortifying the vertebra with PMMA (with the objective of strengthening the screw–bone connection) (Yi et al. 2008) or using coated screws (Sandén et al. 2002) are methods which have gained popularity in the geriatric group. In the case of a healthy child, the challenge is in the cartilaginous structure of the bone and not the insufficiency of bone mineralization. So while these methods may be seen as solutions for aging patients, expecting the same methods to provide an additional advantage for the pediatric age group does not seem rational. One should note that spinal instrumentation is inherently weak in the pediatric age group and perform surgical planning accordingly.

12.3  Growth-Related Problems The negative impact on the growth of the vertebral column and related structures (especially the thorax and lungs) of fusion done in early childhood is unavoidable. Implants like hooks or wires implanted in the posterior elements do not have an additional effect on this negative impact. However, pedicle screws directed to the anterior vertebral body from posterior elements cross the neurocentral cartilage (NCC). NCC is the growth plate of the vertebral body which enables bipolar growth. It is responsible for the growth of the posterior vertebral body and the spinal canal. It is known that metallic implants crossing a growth plate have a negative effect on growth. This effect is especially true for threaded implants occupying a significant percentage of the physeal area and causing compression

12  Instrumentation in the Childhood Spinal Deformities: Challenges, Problems, Limitations, and Solutions

151

a

b

Fig. 12.2  Four year old boy with Triple-A syndrome (a). He was treated with the growing rod technique. Pedicle screws were used on both ends (b)

of the growth plate. Pedicle screws which occupy almost the entire inner diameter of the pedicle and impose an inevitable compressive force on the plate by their threads must clearly affect NCC functions. Cil et al. demonstrated pedicle shortening and narrowing of the spinal canal in immature pigs that underwent pedicle screw instrumentation (Cil et al. 2005) (Fig. 12.4). A similar observation was repeated by Zhang et al., who showed spinal deformity due to pedicle shortening with multileveled mono-lateral screwing on immature animals (Zhang and Sucato 2008). Surprisingly, data on the clinical application of screws on humans do not reflect these concerns. Ruf and Harms (2002) argue that the pedicle screw does not have any negative effect on children treated with it in their early childhood and that the spinal canal continues to grow normally. In an as yet unpublished study

152

12

M. Yazici and D.Z. Olgun

a

b

12  Instrumentation in the Childhood Spinal Deformities: Challenges, Problems, Limitations, and Solutions Fig. 12.4  Unilateral pedicle screws applying compression on the porcine neurocentral cartilage: Planned path of right pedicle screw (line marked 4) plotted on preoperative CT-scan; left pedicle was kept undisturbed (line marked 5) (a) 4-month follow-up CT-scan shows shorter pedicle length and smaller hemi-canal area on the side of the screw (b) (From Cil et al. (2005))

153

a

b

p­ erformed at the authors’ ­institution, 16 patients who received pedicle screw instrumentation before the age of 5 were analyzed regarding the effect of screws on various parameters of vertebral growth as measured on preoperative and follow-up computed tomography images at least 24 months apart. Among these parameters were pedicle length, vertebral body anterior–posterior diameter and spinal canal area. None of the parameters appeared to have been adversely affected by the presence of pedicle screws. The discrepancy between ­animal studies and clinical practices should be noted. Additionally, the effects of pedicle screws on growth must be studied in larger series with long-term follow-up results. Taking into account the significant surgical advantages of pedicle screws, the unlikely possibility of iatrogenic spinal stenosis should not become a reason for abandoning screw

Fig. 12.3  Three year and 8 month old girl with syndromic early onset kyphoscoliosis. Her deformity was very rigid (a). She was treated with the growing rod technique (b). Multiple concave rib osteotomies (arrow) and one-level apical sublaminar wiring were added to procedure. Upper pedicle screws at T3 were supplemented by sublaminar wire (circle)

154

12

M. Yazici and D.Z. Olgun

usage. Like animal studies reveal, even though the screw has an adverse effect on vertebral canal development, the treatment of spinal stenosis in adulthood is always easier than the treatment of severe deformities in early childhood.

12.4  Material-Related Problems Materials used most frequently for modern spinal surgery implants are stainless steel and titanium. Both of these materials are inert and not expected to cause serious biological reactions. Therefore, routine removal of spinal implants is not recommended. The fact that the materials are inert does not necessarily mean that there will be no reaction. In tissue samples taken from patients, whose implants were removed for a reason, generation of wear particles especially around metal–metal connections was observed (Senaran et al. 2004). Moreover, it was determined that these particles induce reactive tissue growth, mostly clinically insignificant, on neighboring tissues. Metal particles (titanium alloy) are detected not only in the surgical field but also in blood plasma and hair. The finding that analyses performed after the removal of implants showed no particles in plasma and hair proves that metal release continues as long as the implant remains in the body (Kasai et al. 2003). Whether these particles create a negative clinical effect is unknown as of yet. However, this matter may have significance in a very young patient who will have to live with the implant for a very long time.

12.5  Conclusion Owing to improvements in the analysis of spinal deformities, anesthesia and intensive care techniques, and implant technology, spinal instrumentation is performed on more children today. Problems with implant profile have been principally overcome, while those with the quality of purchase and effects on growth have not been completely eliminated yet. The growing spine is still – and will likely continue to be – one of the most challenging areas in spinal surgery. Enlightening the biomechanical characteristics of the healthy child’s spine will help us illuminate many unknowns in this field. Development of implants achieving correction of deformities without affecting growth will pave the way to the elimination of numerous problems.

References Ahmadiadli, H., Olgun, D.Z., Yazici, M.: The effect of a new modification of the growing rod technique on the success rate: distal and proximal pedicle screw fixation, dual rod application and routine lengthening at every 6 months. Presented at the 2nd ICEOS Meeting, Montreal, Canada, 2008

12  Instrumentation in the Childhood Spinal Deformities: Challenges, Problems, Limitations, and Solutions

155

Akbarnia, B.A., Asher, M.A., Hess, F., Wagner, T.: Safety of pedicle screw in pediatric patients with scoliosis and kyphosis. Presented at the annual meeting of Scoliosis Research Society, Ottawa, Canada, 1996 Alanay, A., Cil, A., Acaroglu, E., Caglar, O., Akgun, R., Marangoz, S., Yazici, M., Surat, A.: Late spinal cord compression caused by pulled-out thoracic pedicle screws: a case report. Spine 28, E506–E510 (2003) Brown, C.A., Lenke, L.G., Bridwell, K.H., Geideman, W.M., Hasan, S.A., Blanke, K.: Complications of pediatric thoracolumbar and lumbar pedicle screws. Spine 23, 1566–1571 (1998) Burton, D.C., Sama, A.A., Asher, M.A., Burke, S.W., Boachie-Adjei, O., Huang, R.C., Green, D.W., Rawlins, B.A.: The treatment of large (>70 degrees) thoracic idiopathic scoliosis curves with posterior instrumentation and arthrodesis: when is anterior release indicated? Spine 30, 1979–1984 (2005) Butler Jr., T.E., Asher, M.A., Jayaraman, G., Nunley, P.D., Robinson, R.G.: The strength and stiffness of thoracic implant anchors in osteoporotic spines. Spine 19, 1956–1962 (1994) Cil, A., Yazici, M., Daglioglu, K., Aydingoz, U., Alanay, A., Acaroglu, E., Gulsen, M., Surat, A.: The effect of pedicle screw placement with or without application of compression across the neurocentral cartilage on the morphology of the spinal canal and pedicle in immature pigs. Spine 30, 1287–1293 (2005) Erel, N., Sebik, A., Karapinar, L., Gürbulak, E.: Transverse process wiring for thoracic scoliosis: a new technique. Acta Orthop. Scand. 74, 312–321 (2003) Heller, J.G., Shuster, J.K., Hutton, W.C.: Pedicle and transverse process screws of the upper ­thoracic spine. Biomechanical comparison of loads to failure. Spine 24, 654–658 (1999) Kasai, Y., Iida, R., Uchida, A.: Metal concentrations in the serum and hair of patients with titanium alloy spinal implants. Spine 28, 1320–1326 (2003) Kwok, A.W., Finkelstein, J.A., Woodside, T., et al.: Insertional torque and pull-out strengths of conical and cylindrical pedicle screws in cadaveric bone. Spine 21, 2429–2434 (1996) Mahar, A.T., Bagheri, R., Oka, R., Kostial, P., Akbarnia, B.A.: Biomechanical comparison of ­different anchors (foundations) for the pediatric dual growing rod technique. Spine J. 8, 933–939 (2008) Mazda, K., Ilharreborde, B., Even, J., Lefevre, Y., Fitoussi, F., Penneçot, G.F.: Efficacy and safety of posteromedial translation for correction of thoracic curves in adolescent idiopathic ­scoliosis using a new connection to the spine: the Universal Clamp. Eur. Spine J. J18, 158–169 (2009) Rinella, A., Cahill, P., Ghanayem, A., et al.: Thoracic pedicle expansion after pedicle screw placement in a pediatric cadaveric spine: a biomechanical analysis. Presented at the annual meeting of Scoliosis Research Society, Buenos Aires, Argentina, 2004 Ruf, M., Harms, J.: Pedicle screws in 1- and 2-year-old children: technique, complications, and effect on further growth. Spine 27, E460–E466 (2002) Sandén, B., Olerud, C., Petrén-Mallmin, M., Larsson, S.: Hydroxyapatite coating improves fixation of pedicle screws. A clinical study. J. Bone Joint Surg. Br. 84B, 387–391 (2002) Senaran, H., Atilla, P., Kaymaz, F., Acaroglu, E., Surat, A.: Ultrastructural analysis of metallic debris and tissue reaction around spinal implants in patients with late operative site pain. Spine 29, 1618–1623 (2004) Senaran, H., Yazici, M., Karcaaltincaba, M., Alanay, A., Ariyurek, M., Acaroglu, E., Surat, A.: Lumbar pedicle morphology in immature spine. A spiral computed tomographic study. Spine 27, 2472–2476 (2002) Viswanathan, A., Relyea, K., Whitehead, W.E., Curry, D.J., Luerssen, T.G., Jea, A.: Pneumothorax complicating “in-out-in” thoracic pedicle screw placement for kyphotic deformity correction in a child. J. Neurosurg. Pediatr. 2, 379–384 (2008) Wang, M.Y.: Cervical crossing laminar screws: early clinical results and complications. Neurosurgery 61, s311–s315 (2007)

156

12

M. Yazici and D.Z. Olgun

White, K.K., Oka, R., Mahar, A.T., Lowry, A., Garfin, S.R.: Pullout strength of thoracic pedicle screw instrumentation: comparison of the transpedicular and extrapedicular techniques. Spine 31, E355–E358 (2006) Yazici, M., Pekmezci, M., Cil, A., Alanay, A., Acaroglu, E., Oner, F.C.: The effect of pedicle expansion on pedicle morphology and biomechanical stability in the immature porcine spine. Spine 31, E826–E829 (2006) Yi, X., Wang, Y., Lu, H., Li, C., Zhu, T.: Augmentation of pedicle screw fixation strength using an injectable calcium sulfate cement: an in vivo study. Spine 33, 2503–2509 (2008) Yilmaz, G., Demirkiran, G., Ozkan, C., Daglioglu, K., Pekmezci, M., Alanay, A., Yazici, M.: The effect of dilation of pedicles on pull-out strength of the screws in immature pig model: in vivo study. J. Ch’ld. Orthop. 2, S54 (2008) Zhang, H., Sucato, D.J.: Unilateral pedicle screw epiphysiodesis of the neurocentral synchondrosis. Production of idiopathic-like scoliosis in an immature animal model. J. Bone Joint Surg. 90A, 2460–2469 (2008) Zindrick, M.R., Knight, G.W., Sartori, M.J., Carnevale, T.J., Patwardhan, A.G., Lorenz, M.A.: Pedicle morphology of the immature thoracolumbar spine. Spine 25, 2726–2735 (2000)

Fusionless Instrumentation for Non-Idiopathic Spine Deformities of Young Children: The Growing Rod Technique

13

Muharrem Yazici and Z. Deniz Olgun

Progressive scoliosis that cannot be controlled with bracing has to be treated with surgery. Instrumented fusion allows the correction of deformity while preventing progression, but effectively eliminates growth potential. The cessation of growth in turn leads to many problems, including poor cosmesis and permanent pulmonary insufficiency. Results of surgical treatment with the idea of “controlling deformity without causing any damage to the growth potential of the spine” were first published by Moe (Moe et al. 1984). The growing rod technique was originally described for patients with idiopathic or idiopathic-like deformities with normal vertebral anatomy. It basically includes reconstruction of the deformity by a principally distractive maneuver, and has been described by its developers as an internal brace. Flexibility of the curve is the first requirement for successful brace treatment in spinal deformities, and this too is applicable to the growing rod technique. In other words, in order for the growing rod technique to be successful, the deformity should be able to be manipulated by external forces. Early onset scoliosis of many etiologies including connective tissue disorders, neuromuscular diseases, or congenital vertebral malformations are often progressive and poorly controlled by braces. This early and rapid progression can many times lead to a requirement for surgical intervention (Fig.  13.1). If associated malformations do not preclude multiple surgeries and the vertebral morphology is normal, the standard growing rod technique can be successfully implemented in this subgroup of patients as well. While there are no studies specifically reporting the results of non-idiopathic spine deformities treated with the growing rod technique, all major series include several non-idiopathic cases. In

M. Yazici () and Z.D. Olgun Department of Orthopedics, Hacettepe University, Faculty of Medicine, Sihhiye, Ankara 06100, Turkey e-mail: [email protected]; [email protected] M. Yazici (ed.), Non-Idiopathic Spine Deformities in Young Children, DOI: 10.1007/978-3-642-19417-7_13, © 2011 EFORT

157

158 

13

M. Yazici and Z.D. Olgun

a

b

Fig.  13.1  Six-and-a-half-year-old girl with Ehlers–Danlos disease (a). Her deformity is well-­ controlled by the growing rod technique in both coronal and sagittal planes (b)

these papers, success rates of this treatment modality are comparable with those of idiopathic patients (Klemme et al. 1997; Akbarnia et al. 2005; Thompson et al. 2005). In a recent report by Yang et al. (2008), 16 patients with cerebral palsy were treated with the growing rod technique. It was reported that the technique is effective in this group of patients as well. The only significant implant-related complication that was reported was proximal hook dislodgment in one patient. They did, however, draw attention to the fact that this subgroup of patients has many medical complexities and the costs and benefits must be assessed in order to provide the best quality of life for these patients. Spinal muscular atrophy (SMA) is a group of disorders that is almost always accompanied by early onset scoliosis and profound pulmonary disease. Growing rod treatment in the management of early onset scoliosis associated with SMA was recently evaluated in a

13  Fusionless Instrumentation for Non-Idiopathic Spine Deformities of Young Children: The Growing Rod Technique

159

a

b

Fig. 13.2  Four-year-old boy with congenital muscular dystrophy. He presented with a severe and very rigid thoracolumbar scoliosis. Apical vertebral rotation was controlled by concave pedicle screw. All three planes deformities were controlled by growing rod. Clinical and radiographical pictures of the patient, preoperative (a) and postoperative (b)

report by McElroy et al. Fourteen patients with SMA underwent growing rod treatment and were followed for an average of 54 months. It was observed in this study that growing rods improve trunk and lung height while controlling the spinal curve and pelvic obliquity in SMA cases with severe early onset scoliosis. Interestingly, SMA patients were found to have a similar incidence of complications and only slightly longer hospital stays at lengthening procedures when compared with 80 growing rod patients with idiopathic deformities (McElroy et al. 2010) (Figs. 13.2 and 13.3). Congenital malformations represent another common cause for spinal deformity at this age. While these curves can be rigid and many times cannot be controlled adequately with simple distraction, a retrospective examination of the results of growing spine patients reported in the past few years have revealed that this method has been applied often to patients with congenital deformities. This contradicts the basic rationale of the growing rod technique, and raises the question of how rigid deformities secondary to bone anomalies can successfully be treated by this method. First of all, congenital spine deformities represent a heterogeneous group of bone and neural anomalies in the vertebral column. A secondary curve can appear in these patients in order to compensate the deformity caused by the anomalous bony structure and sometimes, become larger than the actual curve itself. This can be noted by a careful examination of the patient’s x-rays. In other patients, especially in Type I curves (hemivertebra only), rigidity can be confined to the apex of the deformity while the segments above and below it may retain some

160 

13

M. Yazici and Z.D. Olgun

a

b

Fig. 13.3  Four-year-old girl. She underwent multilevel laminectomy and spinal cord decompression for a neuroblastoma at the age of 2. During follow-up she developed a collapsing-spine deformity which negatively affected her ability to sit (a). Her spinal deformity – and pelvic obliquity as well – were controlled by the growing rod employing a Galveston-type distal foundation (b)

amount of flexibility. Sometimes, overall trunk imbalance can constitute a bigger problem than the deformity caused by the anomalous bone. Other times, several segments may be involved in the congenital anomaly and preclude treatment with resection. There exist several methods to increase flexibility that can be combined with the growing rod in young children with congenital deformities in order to increase its rate of success. These include but are not limited to concave rib osteotomies and additional anterior

13  Fusionless Instrumentation for Non-Idiopathic Spine Deformities of Young Children: The Growing Rod Technique

161

a

b

Fig. 13.4  Five-year-old girl with congenital spinal deformity. She had an associated intraspinal pathology which was treated by neurosurgical intervention 3 years ago. She had significant trunk imbalance which was corrected with the growing rod method. In order to increase flexibility, multiple concave rib osteotomies were performed at index surgery. Clinical and radiographical pictures of the patient, preoperative (a) and postoperative (b)

annulotomies. These procedures to increase flexibility do not require the exposure of intermediate spinal segments and, therefore, do not negatively affect the growth of the immature spine (Fig. 13.4). In a study by Akbarnia et al. (2005), three patients with congenital deformities were included and showed similar deformity correction and spinal growth rates as idiopathic patients. One of the largest and most inclusive series in the literature was published by Klemme et al. (1997) and includes the data of nine patients with congenital spinal deformities. In this series, spinal growth rates and deformity correction were similar to patients with other diagnoses. Complication rates and the severity of complications were not significantly different (Fig. 13.5). Studies detailing the efficacy and safety of the growing rod technique in only congenital spinal deformities have recently been published. In this multicenter study (Elsebaie et  al. 2011), where 19 congenital scoliosis patients were treated with the growing rod technique and followed for at least 2 years, reported 31% correction in the angle of scoliosis, and an annual average growth of 12 mm of the T1–S1 length. In addition to this, the space available for the lung ratio increased from an average of 0.81 preoperatively to 0.94 postoperatively. Of added importance is the fact that none of these patients suffered a neurological complication throughout the course of treatment (Figs. 13.6 and 13.7).

162 

13

M. Yazici and Z.D. Olgun

a

b

Fig.  13.5  Four-and-a-half-year-old boy with a lower thoracic meningomyelocele. He presented with significant lumbar kyphosis. At index surgery, lumbar kyphosis was corrected with multilevel eggshell osteotomies, followed by the application of the growing rod. During follow-up, the deformity was found to be controlled while growth potential was preserved. Clinical and radiographical pictures of the patient, preoperative (a) and postoperative (b)

In conclusion, the growing rod technique is a safe and reliable method even in the treatment of young children with non-idiopathic deformities. The growing rod technique is a spinal instrumentation method and addresses the spine; as a result, it can be used in patients where the main problem is the deformity of the vertebral column. This includes all etiologies of spinal deformity. While the clinical success of the treatment remains unaffected by underlying pathologies, it should be kept in mind that flexibility of the curve is an important prerequisite and additional procedures to increase it should be employed whenever deemed necessary by the surgeon.

13.1  Technique Preoperative planning is performed using standing AP, lateral and especially traction x-rays, latter of which are taken under general anesthesia. While cantilever torsion maneuvers are also employed, the main corrective force remains distraction during index surgery. This is why basic Harrington principles are used for the selection of levels to be

13  Fusionless Instrumentation for Non-Idiopathic Spine Deformities of Young Children: The Growing Rod Technique

a

b

c

d

163

Fig.  13.6  Three-year-old boy with congenital scoliosis. He had multiple hemivertebrae and a contralateral unsegmented bar at the thoracolumbar region (a). Posterior vertebral column resection was performed at the age of 3 (b). Although hemivertebrectomy site healed completely, global deformity increased during follow-up (c). At the age of 6, implants were removed, and standard growing rod technique was applied (d)

i­nstrumented. For distal and proximal anchor points, vertebrae within the stable zone are selected. The skin incision at index surgery spans the length of the spine from the end points of instrumentation, but only the anchor segments are exposed subperiosteally, while the intermediate segments are left alone. After the insertion of anchor fixation, the facet joints at these levels are excised for fusion. The author prefers to use pedicle screws at both ends of the instrumentation. Inter- and intraspinous ligaments and adjacent facet joint capsules are preserved. Following exposure and instrumentation, rods are contoured according to the sagittal spinal curvature and engaged into the screws. The two rods are usually connected with transverse connectors distally and proximally as necessary. A groove is prepared bilaterally within the paravertebral muscles over the intermediate segments for the rods in order to preclude skin prominence. Using the cantilever torsion maneuver, the proximal and distal rods are aligned with each other and connected with a growing ­end-to-end connector. Distraction and compression maneuvers are applied at this point to

164 

13

M. Yazici and Z.D. Olgun

a

b

Fig.  13.7  Three-year-old girl with congenital scoliosis. She has Arnold–Chiari malformation, syringomyelia and tethered cord (a). Her deformity was treated with magnetic expandable rod (Magec©). Rod was lengthened three times with external actuator (b)

13  Fusionless Instrumentation for Non-Idiopathic Spine Deformities of Young Children: The Growing Rod Technique

165

get a balanced spine. The paravertebral musculature is sutured over the rods and connectors and the skin is closed with subcuticular suture. For the first 6 months following index surgery, a thoracolumbar orthosis is used. The rods are lengthened every 6 months and no external support is necessary after the lengthening procedure.

References Akbarnia, B.A., Marks, D.S., Boachie-Adjei, O., Thompson, A.G., Asher, M.A.: Dual growing rod technique for the treatment of progressive early-onset scoliosis: a multicenter study. Spine 30, S46–S57 (2005) Elsebaie, H.B., Yazici, M., Thompson, G.H., Emans, J.B., Skaggs, D.L., Crawford, A.H., Karlin, L.I., McCarthy, R.E., Poe-Kochert, C., Kostial, P., Akbarnia, B.A.: Safety and efficacy of growing rod technique for pediatric congenital spinal deformities. J Pediatr Orthop 31(1), 1–5 Feb (2011) Klemme, W.R., Denis, F., Winter, R.B., Lonstein, J.W., Koop, S.E.: Spinal instrumentation without fusion for progressive scoliosis in young children. J Pediatr Orthop 17, 734–742 (1997) McElroy, M., Sponseller, P., Shaner, A., Thompson, G., Crawford, T., Kadakia, R., Akbarnia, B., Growing Spine Study Group: Growing rods for scoliosis in spinal muscular atrophy. Structural effects and burden of care. 4th International Congress of Early Onset Scoliosis and Growing Spine, Toronto, Canada, 19–20 November 2010 Moe, J.H., Kharrat, K., Winter, R.B., Cummine, J.L.: Harrington instrumentation without fusion plus external orthotic support for the treatment of difficult curvature problems in young children. Clin Orthop Relat Res 185, 35–45 (1984) Thompson, G.H., Akbarnia, B.A., Kostial, P., Poe-Kochert, C., Armstrong, D.G., Roh, J., Lowe, R., Asher, M.A., Marks, D.S.: Comparison of single and dual growing rod techniques followed through definitive surgery: a preliminary study. Spine 30, 2039–2044 (2005) Yang, J., Sponseller, P., Thompson, G.H., Asher, M.A., Salari, P., Akbarnia, B.: Growing rods in cerebral palsy. 2nd International Congress of Early Onset Scoliosis and Growing Spine, 7–8 November 2008, Montreal, Canada (2008)

 

VEPTR Instrumentation in Early Onset Scoliosis

14

Fritz Hefti, Arne Mehrkens, and Carol-Claudius Hasler

VEPTR has been developed for the treatment of thoracic insufficiency syndrome in cases of congenital scoliosis with or without rib fusions (Campbell and Hell-Vocke 2003; Campbell et al. 2004). In May 2002 we started to use it for this purpose as the first center outside USA (Hell et al. 2005). At that time, VEPTR was admitted in USA for these indications only. R. Campbell encouraged us to explore the use of this implant for other types of early onset scoliosis. VEPTR is now one of the options in the treatment for this indication. The method is an alternative to brace treatment, serial casting, active and passive “growing rods,” convex tethering with staples, and – maybe in the near future – true externally commanded growing rods. The efficacy of VEPTR instrumentation in controlling complex congenital spine deformities (Campbell and Hell-Vocke 2003; Campbell et  al. 2004; Emans et al. 2005; Hell et al. 2005), the relative ease of application and the spinesparing approach has stimulated many surgeons to expand its field of application beyond the primary scope of thoracic insufficiency syndromes to non-congenital spine deformities of unknown, neuromuscular, or syndromic origin. VEPTR’s inherent repetitive lengthening may overcome well-defined post-fusion issues like short trunk, poor pulmonary function, and crankshaft phenomenon by compensating ongoing spine growth as the main deteriorating force in those skeletally immature patients. However, this potential and the control of scoliosis, hyperkyphosis, and pelvic obliquity remain still to be shown in noncongenital deformities.

F. Hefti (), A. Mehrkens, and C.-C. Hasler Orthopaedic Department, University Children’s Hospital (UKBB), Spitalstrasse 33, 4056 Basel, Switzerland e-mail: [email protected]; [email protected]

M. Yazici (ed.), Non-Idiopathic Spine Deformities in Young Children, DOI: 10.1007/978-3-642-19417-7_14, © 2011 EFORT

167

168 

14

F. Hefti et al.

14.1  VEPTR in Non-congenital Scoliosis Patients with a diagnosis of progressive non-congenital scoliosis or kyphosis, not responding to or progressed during brace treatment (>40° Cobb angle) were studied under approval of the local ethical committee. All had undergone VEPTR instrumentation at a single institution by two surgeons (F.H., C.H.) with a minimum follow-up time of 1 year (index surgery and at least two expansion procedures). Patients with rib fusions or congenital vertebral anomalies as the main underlying deforming cause were excluded. All patients had a complete series of radiographs, clinical photographs and thorough documentation of their history and laboratory findings according to a protocol initiated at the introduction of VEPTR at our institution in 2002. Routine VEPTR protocol included preimplant antero-posterior (AP) and ­lateral radiographs of the entire spine and clinical photographs, standing in ambulatory and sitting in non-ambulatory patients. Routine expansion surgery was performed at 6-month intervals with pre- and postoperative AP and lateral radiographs and preoperative photo documentation. Frontal Cobb angles, sagittal profile, and pelvic obliquity were digitally measured (AxioVision Rel.4.4 Carl Zeiss, Jena Germany) by one of us (C.H.) on all radiographs. T1 tilt (Campbell and Hell-Vocke 2003) was assessed on pre- and postimplant radiographs and after the last expansion procedure. Pelvic obliquities and T1 tilts of more than 10° were defined to be pathologic. The exact diagnosis, comorbidities, VEPTR constructs used, changes of strategy, and replacement surgeries and complications were recorded. Since May 2002 we have used VEPTR in 57 cases. Of them 23 were non-congenital early onset scolioses. All patients had previously been treated with a brace. The indication for the intervention was failure of brace treatment. Diagnoses of patients with non-congenital scoliosis: Neuromuscular scoliosis

11

  Cerebral palsy

2

  Myelomeningocele

9

Post-thoracotomy early onset scoliosis

2

Infantile hyperkyphosis

2

Myopathy

1

Syndromic scoliosis

5

Compensatory curve in Sprengel’s deformity

1

Idiopathic early onset scoliosis

1

Total

23

The average age at time of the first operation was 5 years 9 months (between 1 year 1 month and 10 years 5 months). The overall number of operations was 105 (revision surgeries excepted). Usually, the rods were lengthened with a small surgical intervention every 6 months. The follow-up time was 3 years 1 month on average (between 1 year and 6 years 3 months).

14  VEPTR Instrumentation in Early Onset Scoliosis

169

14.2  Results The Cobb angle in the frontal plane was 68° before the first intervention (between 11° and 111°). Postoperatively it was 48° (between 10° and 86°). Initial correction was therefore 30%. After an average follow-up time of 3 years, the Cobb angle was 54° (between 0° and 105°). The remaining correction was now 21%. Three of the cases did not show correction, the Cobb angle at follow-up in these cases was slightly bigger than at the beginning. The pelvic obliquity before the first intervention was 34° on average (between 13° and 60°), postoperatively it was 15° (between 1° and 41°), and at follow-up it was 17° (between 0° and 42°). The average correction was 54%; all improved more than 5°. The Cobb angle in the sagittal plane (+ = kyphosis; − = lordosis): The thoracic Cobb angle before the initial procedure was 55° on average (between −44° and 128°), postoperatively it was 46° on average (between −33° and 107°). At follow-up it averaged 55° (between −33° and 94°). In eight patients the kyphosis increased by 27° on average (between 9° and 65°). The reasons were junctional kyphosis or increase at the instrumented levels. The lumbar sagittal Cobb angle before the first intervention was −46° on average (between −89 and +70°); postoperatively it averaged −40° (between −79° and +76°). At follow-up it was −32° (between −97° and +74°).

14.3  Complications Thirteen patients sustained 19 complications; 15 revisions were necessary. Skin slough was the most common complication (10×); implant dislocation or breakage occurred 7× and deep infections 2×. The risk of complication after the initial procedure was 23%, after a lengthening procedure it was 16%. The overall risk was 18%.

14.4  Discussion VEPTR is very effective in correcting loss of balance and pelvic obliquity. Especially when using the so-called Eiffel tower procedure (bilateral bar from the ribs to the pelvis (Smith 2008)), even in severe cases of loss of balance it can be corrected by more than 50%. Loss of balance is a common problem in early onset scoliosis, especially in neuromuscular and syndromic cases. As the rods are anchored at the pelvis, the lever arm for the correction pelvic of obliquity and spinal imbalance is better than with implants that are fixed to the spine. In several cases we observed a significant improvement of gait after correction with VEPTR and restoration of balance.

170 

14

F. Hefti et al.

VEPTR is less effective in correcting the spinal curve itself compared to growing rods (Akbarnia et al. 2005; Thompson et al. 2005, 2007). This can be easily ­understood as the correcting forces act farther away from the spine as compared to growing rods. Correction in our cases was only 25%. Initial correction is maintained but generally not further improved with subsequent lengthenings. In more recent cases we placed the bars closer to the spine; we then had a better effect on the spinal curvature. VEPTR can have a kyphosing effect. This can especially be noted when a junctional kyphosis is created in the thoraco-lumbar or the upper thoracic area. It can be avoided in using threads to bind the bar to several ribs, thus distributing the forces over the whole instrumented area. On the other hand, patients with excessive early onset kyphosis can be successfully treated with bilateral rib-to-pelvis constructs (so-called Eiffel tower construct). The rib cradles have to be placed as high (to the second or third ribs) and as laterally as possible. The rods thus are placed anterior to the apex of the kyphosis and therefore have good corrective effect. Others have made similar observations in myelomeningocele cases (Latalski et al. 2008). The complication rate of VEPTR is relatively high and is related to the repetitive surgery. It has to be compared with the complication rate when using growing rods with active repetitive lengthenings. The ratio seems to be comparable. It is significantly higher than in passive growth modulating rods. The most common reason for revision was skin slough followed by implant dislocation or breakage. One big advantage of VEPTR, on the other hand, is the fact that no brace is needed. This demonstrates that spinal cord monitoring is very important when installing VEPTR. The infantile spine is more flexible than the spinal cord as we know from trauma cases. Comparing with spinal implants VEPTR has some advantages and disadvantages. As it is not placed at the spine itself the risk of spontaneous stiffening of the spine seems to be smaller. Unfortunately, this risk is very poorly investigated in the existing literature on growing rods. In our own experience it takes about 3 years, until the instrumented area becomes stiff and thus does not allow further lengthening. In the VEPTR concept, the spine itself is not put in splints. On the contrary, there is constant movement between the ribs and the spine when breathing. On the other hand, there is scar formation between the ribs. Therefore some stiffening also occurs. The scar formation has to be released after a few years. So far we have no data about spinal mobility after implant removal, but some stiffening of the spine seems to occur in spite of the movements between ribs and spine. The parents very well accept VEPTR, as they are less afraid of neurological complications as if spinal implants are used. In fact, we never had a serious neurological complication. In one case of a very young patient the MEP-signals disappeared after distraction but reappeared a few minutes after releasing the distractive forces. The patient had no neurological sequelae. Objectively, however, the neurological risk when using VEPTR or spinal implants is also low, but not neglectable (Sankar et al. 2008; Skaggs et al. 2009). We are currently measuring the space available for lung in the VEPTR cases but we cannot make any statement on this issue yet. Although in these non-congenital cases there are no rib fusions, lung function in these young patients remains a ­concern, especially in presence of severe curvatures. Since April 2007, VEPTR is admitted in USA for the indications which are mentioned in this article, especially for syndromic and neuromuscular early onset scoliosis.

14  VEPTR Instrumentation in Early Onset Scoliosis

171

14.5  Conclusion VEPTR allows controlling early onset scoliosis and results in a moderate correction of the curvature. It is very effective for the correction of spinal balance and pelvic obliquity. It has the advantage that no brace is needed and there is movement between the place of anchorage (the ribs) and the spine. Due to the fact that repetitive lengthening procedures are necessary there is a relatively high complications rate. Complications are, however, usually not very severe. VEPTR has a better acceptance from the parents than spinal implants, as they fear less the neurological complications. The optimal treatment for early onset scoliosis is not yet available. We need an implant which can be continuously lengthened with external command. Such implants are currently developed. They will have a better effect on spinal and thoracic growth than the passive growing rods such as the new Shilla growth guidance system (McCarthy et al. 2008). Whether these new active systems will be used at the spine or at the ribs will depend on the indication. In presence of thoracic insufficiency syndrome they must be applied at the ribs. Another good indication for using the implants outside the spine is the severe loss of balance.

References Akbarnia, B.A., Marks, D.S., Boachie-Adjei, O., Thompson, A.G., Asher, M.A.: Dual growing rod technique for the treatment of progressive early-onset scoliosis: a multicenter study. Spine 30, S46–S57 (2005) Campbell Jr., R.M., Hell-Vocke, A.K.: Growth of the thoracic spine in congenital scoliosis after expansion thoracoplasty. J. Bone Joint Surg. Am. 85-A, 409–420 (2003) Campbell Jr., R.M., Smith, M.D., Mayes, T.C., Mangos, J.A., Willey-Courand, D.B., Kose, N., Pinero, R.F., Alder, M.E., Duong, H.L., Surber, J.L.: The effect of opening wedge thoracostomy on thoracic insufficiency syndrome associated with fused ribs and congenital scoliosis. J. Bone Joint Surg. Am. 86-A, 1659–1674 (2004) Emans, J.B., Caubet, J.F., Ordonez, C.L., Lee, E.Y., Ciarlo, M.: The treatment of spine and chest wall deformities with fused ribs by expansion thoracostomy and insertion of vertical expandable prosthetic titanium rib: growth of thoracic spine and improvement of lung volumes. Spine 30(Suppl), S58–S68 (2005) Hell, A.K., Campbell, R.M., Hefti, F.: The vertical expandable prosthetic titanium rib implant for the treatment of thoracic insufficiency syndrome associated with congenital and neuromuscular scoliosis in young children. J. Pediatr. Orthop. B 14, 287–293 (2005) Latalski, M., Fatyga, M., Raganowicz, T., Gregosiewicz, A.: VEPTR as an alternative for early kyphectomy in children congenital kyphosis in myelomeningocele (abstract). 2nd International Congress on Early Onset Scoliosis & Growing Spine (ICEOS), Montreal (2008) McCarthy, R., McCullough, F., Luhmann, S., Lenke, L.: Greater than two years follow-up Shilla growth enhancing system for the treatment of scoliosis in children (abstract). 2nd International Congress on Early Onset Scoliosis & Growing Spine (ICEOS), Montreal (2008) Sankar, W., Skaggs, D., Emans, J., Marks, D., Dormans, J., Thompson, G., Shah, S., Sponseller, P., Akbarnia, B.A.: Neurologic risk in growing rod spine surgery in early onset scoliosis (abstract). 2nd International Congress on Early Onset Scoliosis & Growing Spine (ICEOS), Montreal (2008)

172 

14

F. Hefti et al.

Skaggs, D.L., Choi, P.D., Rice, C., Emans, J., Song, K.M., Smith, J.T., Campbell, R.M.: Efficacy of intraoperative neurologic monitoring in surgery involving a vertical expandable prosthetic titanium rib for early-onset spinal deformity. J. Bone Joint Surg. Am. 91(7), 1657–1663 (2009) Smith, J.M.S.: Treatment of progressive spinal deformity using the VEPTR device with a bilateral percutaneous rib to pelvis technique in non-ambulatory children with neuromuscular disease (abstract). 2nd International Congress on Early Onset Scoliosis & Growing Spine (ICEOS), Montreal (2008) Thompson, G.H., Akbarnia, B.A., Kostial, P., Poe-Kochert, C., Armstrong, D.G., Roh, J., Lowe, R., Asher, M.A., Marks, D.S.: Comparison of single and dual growing rod techniques followed through definitive surgery: a preliminary study. Spine 30, 2039–2044 (2005) Thompson, G.H., Akbarnia, B.A., Campbell, R.M.: Growing rod techniques in early-onset ­scoliosis. J. Pediatr. Orthop. 27, 354–361 (2007)

Index

A Adam’s forward-bending test, 18 Angle of trunk rotation, 18 Arm spans, 18 Arnold–Chiari malformation, 164 Arthrogryposis multiplex congenita, 99 Atypical scoliosis, 38 Axillary or groin freckles, 18 B Bracing, 60, 74, 88, 110 C Café-au-lait spots, 18 Cantilever torsion, 163 Cardiac anomalies, 56 Casting, 112 Cerebral palsy, 77, 158, 168 Cervical spine growth, 5 Chiari malformation, 38, 54, 61 Cobb angle, 34 Computed tomography, 36–38 Congenital cardiac anomalies, 23 Congenital deformities, 8, 45, 159, 167 Congenital myopathies, 99 Convex growth arrest procedure (convex hemiepiphysiodesis), 61, 63–65, 136 Crankshaft phenomenon, 9, 28, 61, 84 D Deep wound infections, 84 Delaying tactics, 112, 126 Diastematomyelia, 54, 61 Digital skeletal age, 29–30 Dorsal rhizotomy, 81 Duchenne’s muscular dystrophy, 87 Dysraphism, 55 Dystrophin, 87

E Early onset scoliosis, 10, 121, 157, 168 Eiffel tower construct, 98, 170 Etiology, 31 Evaluation, 17 Examination, 17 F Failures of vertebral formation, 46–47 Failures of vertebral segmentation, 47 Friedreich ataxia, 99 Fulcrum-bending films, 33 Fully segmented hemivertebra, 50 G Growing rods, 10, 69, 98, 109, 157, 167 Growth, 3 modulation, 133 preservation techniques, 69–70 sparing, 74 of spine, 3 Guided growth, 131 H Hairy patches, 18 Halo-gravity traction, 115–119 Hemangiomas, 18 Hemivertebrae, 47 Hemivertebra resection, 65–67 Hooks, 146 Hueter-Volkmann, 134 Hyperlaxity, 18, 22 Hypotonia, 73 I Iliac apophysis, 26 Imaging, 26, 58–59 Implant profile, 146

M. Yazici (ed.), Non-Idiopathic Spine Deformities in Young Children, DOI: 10.1007/978-3-642-19417-7, © 2011 EFORT

173

174 Incarcerated hemivertebra, 53 In situ spinal fusion, 61–63 Instrumented correction and fusion, 67 Intraspinal lipomas, 55 K Klippel–Feil syndrome, 118 Kugelberg–Welander, 88 L Leg length discrepancy, 18 Length of spine, 4 Lung, 3 growth, 8 volumes, 36 M Magnetic expandable rod, 164 Magnetic resonance imaging, 38–39 Marionette sign, 97 MEP. See Motor-evoked potential (MEP) Mixed anomalies, 47 MMC. See Myelomeningocele (MMC) Motor-evoked potential (MEP), 74, 82, 170 Myelomeningocele (MMC), 97, 167 Myopathy, 168 N Neural axis abnormalities, 25, 38 Neurocentral cartilage (synchondrosis), 136, 150 Neurofibromatosis, 99 Neurologic examination, 22 Neuromuscular scoliosis, 73 Non-fusion instrumentation, 150 O Olecranon method, 29 Orthotics, 80 Ossification, 4 Osteotomies, 67 P Pedicle length, 153 Pedicle screws, 146 Pelvic obliquity, 89, 169 PMMA, 150 Prader–Willi syndrome, 99 Pseudohypertrophy, 87

Index R Restrictive lung disease, 8 Rett syndrome, 99 Rib anomalies, 46 Risser sign, 26 S Sauvegrain method, 28 Semi-segmented hemivertebra, 51 Serial casting, 74 Shilla procedure, 11, 131, 171 Side-bending films, 32 Sinuses, 18 Sitting height, 4 Skeletal age, 26 Skeletal maturity markers, 26–50 Somatosensory-evoked potential (SSEP), 74, 82 Space available for lung, 170 Spasticity, 73 Spina bifida, 97 Spinal canal area, 153 Spinal canal growth, 6 Spinal dysraphism, 18 Spinal muscular atrophy, 158 Spinal penetration index, 34–36 Spinous process wires, 146 Spondylothoracic dysplasia, 8 Sprengel’s shoulder, 57 Standing height, 4 Stapling, 135 Sublaminar wires, 146 Syndromic scoliosis, 168 Syringomyelia, 38, 54, 164 T Tethered cord, 54, 61, 164 Thoracic cage, 3 Thoracic growth, 6 Thoracic hypokyphosis, 10 Thoracic insufficiency syndrome, 23, 69, 109, 121, 167 Thumb excursion test, 21 Tight filum terminale, 55 Traction films, 33 Transverse process wires, 146 Triradiate cartilage, 28 T1–S1 growth, 5 U Unsegmented bar, 47, 53

175

Index V VACTERL, 54 VATER, 54 VEPTR, 10, 69, 74, 98, 167 Vertebral anomalies, 46 Vertebral column resection, 67

W Wear particles, 154 Werdnig–Hoffmann, 88 Windswept thorax, 129