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Orthopaedics and Trauma Elsevier, ISSN: 1877-1327, http://www.sciencedirect.com/science/journal/18771327 Volume 25, Issue 2, Pages 79-160 (April 2011) 1
Editorial Board, Page i
Mini-Symposium: Radiology 2
(i) Patient selection criteria for vertebroplasty or kyphoplasty in painful osteoporotic fracture, Pages 79-82 Richard W. Whitehouse
3
(ii) Polytrauma imaging – the role of integrated imaging, Pages 83-90 Dominic Barron
4
(iii) The basic science of nuclear medicine, Pages 91-108 Michael L. Waller, Fahmid U. Chowdhury
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(iv) Imaging of non-accidental injury, Pages 109-118 Jeannette K. Kraft
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(v) The basic science of MRI, Pages 119-130 Richard J. Hodgson
Syndrome 7
Sprengel’s deformity, Pages 131-134 Lucy Radmore, William Thomas, Andrew Tasker, Donna Diamond, Rouin Amirfeyz, Martin Gargan
Rehabilitation 8
Upper limb prosthetic rehabilitation, Pages 135-142 Sachin Watve, Greg Dodd, Ruth MacDonald, Elizabeth R. Stoppard
Hand 9
Congenital hand anomalies, Pages 143-154 Gráinne Bourke
CME Section 10
CME questions based on the Mini-Symposium on “Imaging”, Pages 155-156
11
Answers to CME questions based on the Mini-Symposium on “Pathology”, Page 157
Book Reviews 12
Paediatric orthopaedics: a system of decision-making, Page 158 Brian Scott
13
Musculoskeletal oncology: benign tumors (DVD-ROM), Page 158 Robert U. Ashford
14
Children’s Orthopaedics and Fractures, Page 158 J. Mark H. Paterson
15
Musculoskeletal Infection: AAOS Orthopaedic Knowledge Update, Pages 158-159 Martin McNally
Orthopaedics and Trauma Orthopaedics and Trauma presents a unique collection of International review articles summarizing the current state of knowledge in orthopaedics. Each issue begins with a focus on a specific area of the orthopaedic knowledge syllabus, covering several related topics in a mini-symposium; other articles complement this to ensure that the breadth of orthopaedic learning is supplemented in a 4 year cycle. To facilitate those requiring evidence of participation in Continuing Professional Development there is a questionnaire linked to the mini-symposium that can be marked and certified in the Editorial office.
Editor-in-Chief D Limb BSc FRCS Ed (Orth) Leeds General Infirmary, Leeds, UK
Editorial Committee M A Farquharson-Roberts (Gosport, UK), I Leslie (Bristol, UK) M Macnicol (Edinburgh, UK), I McDermott (London, UK), J Rankine (Leeds, UK)
Editorial Advisory Board D C Davidson (Australia) J Harris (Australia) G R Velloso (Brazil) P N Soucacos (Greece) A K Mukherjee (India) A Kusakabe (Japan) M-S Moon (Korea) R Castelein (The Netherlands) R K Marti (The Netherlands) G Hooper (New Zealand)
Emeritus Editor Professor R A Dickson MA ChM FRCS DSc Leeds General Infirmary, Leeds, UK
A Thurston (New Zealand) E G Pasion (Philippines) L de Almeida (Portugal) G P Songcharoen (Thailand) R W Bucholz (USA) R W Gaines (USA) S L Weinstein (USA) M Bumbasirevic (former Yugoslavia)
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(i) Patient selection criteria for vertebroplasty or kyphoplasty in painful osteoporotic fracture
consequently underpowered. The sham procedure had an active component, which was bupivicaine injection around the posterior elements at the painful level. Selection criteria included pain for up to 12 months from presumed date of fracture. In the same period a larger but non-blinded randomized trial of kyphoplasty versus best medical management showed significant benefit to kyphoplasty5 and more recently a similar trial of vertebroplasty versus best medical management also showed significant benefit to vertebroplasty.6 It is tempting to invoke the placebo effect in order to explain these discrepant results but in reality the explanation for differing results between these trials will be multifactorial. Although there are many differences between these trials, the greatest difference in the patient selection criteria was the maximum duration of pain since fracture. If vertebroplasty and kyphoplasty are to retain a place in the management of painful osteoporotic fracture, it is clear that the selection criteria must be sufficiently robust to identify patients that will genuinely benefit from the procedure, over and above any less invasive treatment (which may include bupivicaine injection). For patients enrolled into the sham-controlled trials this was not the case. Notwithstanding the differences between the studies, comparisons of the outcomes in the two main arms of each study are illuminating. In each study there was a group of patients that did not receive cement augmentation. The change in mean pain score in each group is compared between the studies in Figure 1. As patients in the Kallmes study3 were allowed to change over from the initial treatment to the alternative treatment at 1 month, the data line for that study is truncated at this point. Despite the lack of statistical analysis, this simple comparison illustrates several important features: As is well known, back pain after osteoporotic vertebral fracture improves with time, even in patients selected for trials on the basis of severe and apparently unremitting pain thought appropriate for treatment with cement augmentation.
Richard W Whitehouse
Abstract Vertebroplasty and kyphoplasty are radiologically guided percutaneous procedures comprising the injection of bone cement into painful vertebral fractures for the purposes of pain relief. There has been considerable recent debate on the efficacy of these procedures for painful osteoporotic fracture. It is likely that this was due to insufficiently robust patient selection criteria in studies that showed no benefit to the procedure. Using the currently available literature, selection criteria are suggested that should restrict this procedure to those patients likely to benefit.
Keywords kyphoplasty; osteoporosis; vertebral fracture; vertebroplasty
Vertebroplasty is the augmentation of a vertebral body with bone cement, usually by the injection of cement through a needle placed percutaneously under radiographic guidance. Kyphoplasty is an extension of this procedure, where a balloon or other expanding device is first passed into the vertebra and used to reduce the wedge or compression deformity of the fracture before filling the consequent intraosseous cavity with cement. The procedures have become increasingly popular for the treatment of painful vertebral fractures in the last 2 decades, apparently offering almost immediate and permanent relief of pain. All of us who perform these procedures have many examples of patients who were bed-ridden, on opiate analgesia the day before cement augmentation, and were ambulatory, and almost pain free, off all analgesia the day after the procedure.1 Until recently, the published evidence for the efficacy of this procedure was largely based on uncontrolled case series. An editorial in the BMJ in 2008 stated that “consensus on the indications is needed to avoid indiscriminate use” and that “randomized controlled trials are essential to define the minimum conservative treatment that patients should receive before vertebroplasty”.2 In the last year, two publications cast doubt on the value of vertebroplasty for painful osteoporotic fracture.3,4 Both were randomized, blinded trials comparing vertebroplasty with a “sham” procedure and neither showed any statistically significant benefit of vertebroplasty over the sham procedure. Since publication, these studies have been extensively and repeatedly reviewed, discussed and criticized. In both studies patient recruitment was slow, both studies were considerably smaller than originally planned and were
Controls
8 7
VAS pain score
6 5 4 3 2 1 0 0
Wardlaw
10
15 Weeks
Buchbinder
20
Kallmes
25
30
Klazen
Figure 1 Pain scores in the control arms of vertebral cement augmentation trials. Studies by Buchbinder4 and Kallmes3 both show an initial dip, consistent with a therapeutic effect of the “sham” procedure (bupivicaine infiltration).
Richard W Whitehouse MB ChB MD FRCR Consultant Musculoskeletal Radiologist, Manchester Royal Infirmary, Oxford Road, Manchester M13 9WL, UK. Conflicts of interest: none.
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There is, however a late slight increase in pain score in this group, which may reflect the onset of secondary mechanical back pain, rather than fracture pain per se. For the patients that did receive cement augmentation, the comparison is also illuminating (Figure 2): The longer since pain (fracture) onset, the less marked the benefit of cement augmentation. The longer since pain (fracture) onset, the less rapid the post procedural reduction in pain. In these comparisons I have not considered kyphoplasty to be any different from vertebroplasty in its efficacy for pain relief. The main advantages of kyphoplasty are the potential for restoration of vertebral height and the creation of a cavity of known volume, into which cement can be injected with lower risk of cement leakage and consequent reduced risk of complications. The reduced kyphosis and consequently improved biomechanics that may be achieved has theoretical potential to reduce the risk of subsequent mechanical back pain and also the risk of subsequent further osteoporotic vertebral fracture. For kyphoplasty to be effective in reducing kyphosis and elevating the fracture, it is recommended that the procedure be performed within a few weeks of fracture as after this time fracture healing is likely to prevent any restoration of vertebral height, though a cavity will still be created within the vertebra. I have not included the results from a further recent vertebroplasty study performed by Rousing et al7 in this comparison, as although this study showed almost immediate short term benefit for vertebroplasty over conservative treatment in patients who were treated within 8 weeks of pain onset, both the vertebroplasty and conservatively treated patient groups showed considerably better long-term outcomes than in all the other studies, suggesting a significant difference in the patient population selected for this study. Mechanical back pain is common in the patient population that suffers osteoporotic fracture and may be exacerbated by fracture deformity, without necessarily being directly due to the fracture. None of the studies in this review attempted to quantify
Cement augmentation response 8 7 VAS pain score
6 5 4 3 2 1 0 0
5
10
15
20
25
30
Weeks Control Kallmes
Wardlaw Klazen
Buchbinder
Figure 2 Pain scores in the treatment arms of vertebral cement augmentation trials. The control line, for comparison purposes, is from the study by Wardlaw et al.5 Note that the pain duration prior to treatment was up to 12 months in studies by Buchbinder et al4 and Kallmes et al3, up to 3 months for Wardlaw et al5 and up to 2 months for Klazen et al.6
Patients with pain of up to 1 year in duration get immediate reduction in pain from a “sham” procedure, which then returns to the expected pain line for conservatively managed patients within 4 weeks. This suggests a significant temporary benefit of bupivicaine injection, of sufficient duration to tide the patient over until the residual back pain is more tolerable. Patients selected much closer to the time of onset of pain (for example the Klazen study6) have a higher average pain score but a more rapid reduction in pain over the first few weeks, consistent with the expected resolution of acute fracture pain.
Figure 3 Redrawn from Sugita et al 2005.8 Swelledefronted, bow-shaped and projecting fracture morphologies have a high risk of progressive fracture deformity.
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the level of pre-fracture back pain that must have been present in many patients included in these trials. Before finalizing criteria for patient selection, there is one further consideration e some fractures are known to progress to greater deformity over a few weeks after the initial fracture event, € mmel in 1891. The aetia phenomenon originally described by Ku ology of this process is thought to be avascular necrosis and development of a fracture cleft within the vertebra. Such fractures may be persistently painful during the progressive deformity phase, pain may then persist further if there is an osteonecrotic fracture cleft and the more marked final deformity may also predispose to mechanical back pain. Is it possible to predict which fractures may progress in this way from the initial imaging findings? There is one published study that suggests this is the case.8 In this study, the initial fracture morphology on a lateral plain radiograph could be placed into one of five categories (Figure 3), with fracture progression occurring in 87e100% of categories 1e3 and only 12% of categories 4 and 5. If immediate vertebroplasty were offered to patients with fractures in categories 1e3 then fracture progression would be prevented. Those patients that declined this initial invitation but then suffered protracted pain and fracture progression could still be offered kyphoplasty at a time when this procedure is likely to be effective in height restoration and pain relief. The fracture deformities illustrated in this study were of relatively minor degree on the initial radiographs, consequently approaches to patient selection based upon initial fracture morphology would require prompt recognition of the significance of such apparently minor fracture deformities with urgent early referral to an appropriate vertebroplasty service. In order to regain confidence in cement augmentation I believe there is currently a need for patient selection criteria to be robust and proscriptive, so that the population of patients offered these procedures are highly likely to benefit. Although the BMJ editorial suggested that a minimum time for conservative treatment needed to be defined, the comparison of studies described here suggests that a maximum time of fracture pain duration after which cement augmentation is unlikely to be effective is more important. Studies based on selection criteria such as those suggested below are now needed. Back pain not conforming to these criteria should only be offered cement augmentation in the context of a trial to determine whether these criteria are too proscriptive. Suggested selection criteria for cement augmentation of painful osteoporotic vertebral fracture should include all of the following: Pain of sufficient severity to warrant intervention (e.g. Visual Analogue Pain score greater than six), not adequately controlled by other treatments.
Pain clinically likely to be due to fracture (at a site that corresponds to the fracture, nature of the pain, with local tenderness to percussion). Fracture demonstrated on MR to be un-united (marrow oedema and/or fracture cleft). Pain of less than 10 weeks duration by the time of the procedure. These criteria are abbreviated and tabulated for reference (Table 1). The following additional indications are also suggested, though further studies to confirm the value of cement augmentation in these settings are needed: Initial fracture morphology predictive of progression (offer immediate augmentation). Pain of greater than 10 weeks duration should only be offered cement augmentation if MR demonstrates a fracture cleft.9 Initially conservative treatment should be recommended in those patients with fracture morphology unlikely to progress, unless pain is uncontrollable. Whether vertebroplasty or kyphoplasty is preferred for cement augmentation is dependent on other factors; kyphoplasty is potentially more valuable in those fractures where reduction of kyphosis is likely to be achieved, but operator familiarity with the procedure is also a requisite. Complications are less common in kyphoplasty than vertebroplasty, though this is largely accounted for by reduction in the common complication of asymptomatic cement leakage into the paraspinal soft tissues that may occur.
Summary Patient selection criteria for cement augmentation of painful osteoporotic fracture must be robust and stringent to avoid unnecessary procedures. The most significant selection criterion is the duration of pain since fracture. Pain from fractures more than 10 weeks old is unlikely to be relieved by cement augmentation as the cause of persisting pain beyond this time is likely to be multifactorial, with mechanical back pain replacing true fracture pain. An exception to this 10-week criterion may be the presence of an un-united fracture cleft within the vertebra. A
REFERENCES 1 Orr RD. Vertebroplasty, cognitive dissonance, and evidence based medicine: what do we do when the “evidence” says we are wrong? Cleve Clin J Med 2010; 77: 8e11. 2 Lambert RGW, Golmohammadi K. Vertebroplasty for osteoporotic vertebral fracture. Consensus on the indications is needed to avoid indiscriminate use. BMJ 2008; 336: 1261e2. 3 Kallmes DF, Comstock BA, Heagerty PJ, et al. A randomized trial of vertebroplasty for osteoporotic spinal fractures. N Engl J Med 2009; 361: 569e79. 4 Buchbinder R, Osborne RH, Ebeling PR, et al. A randomized trial of vertebroplasty for painful osteoporotic vertebral fractures. N Engl J Med 2009; 361: 557e68. 5 Wardlaw W, Cummings SR, Van Meirhaeghe J, et al. Efficacy and safety of balloon kyphoplasty compared with non-surgical care for vertebral compression fracture (FREE): a randomised controlled trial. Lancet 2009; 373: 1016e24.
Selection criteria for cement augmentation VAS pain score greater than six Pain nature and site consistent with fracture Local tenderness to percussion Pain of less than 10 weeks duration Fracture un-united on MR scan Table 1
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6 Klazen CAH, Lohle PNM, de Vries J, et al. Vertebroplasty versus conservative treatment in acute osteoporotic vertebral compression fractures (Vertos II): an open-label randomised trial. Lancet 2010; 376: 1085e92. 7 Rousing R, Hansen KL, Andersen MO, Jespersen SM, Thomsen K, Lauritsen JM. Twelve-months follow-up in forty-nine patients with acute/semiacute osteoporotic vertebral fractures treated
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conservatively or with percutaneous vertebroplasty. A clinical randomized study. Spine 2010; 35: 478e82. 8 Sugita M, Watanabe N, Mikami Y, Hase H, Kubo T. Classification of vertebral compression fractures in the osteoporotic spine. J Spinal Disord Tech 2005; 18: 376e81. 9 Gangi A, Clark WA. Have recent vertebroplasty trials changed the indications for vertebroplasty? Cardiovasc Intervent Radiol 2010; 33: 677e80.
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(ii) Polytrauma imaging e the role of integrated imaging
ATLS has a very specific statement, in bold letters, about the use of CT in the acute trauma patient: “It is a time consuming procedure that should be only used in patients with no haemodynamic abnormalities in whom there is no apparent indication for an emergency laparotomy”.1 In other words, according to ATLS guidelines, CT is reserved for the haemodynamically stable patient. The latest ATLS manual however has recognized that angiography is a suitable treatment pathway for intra-pelvic bleeding. It does not explain how this will be diagnosed without a prior CT and fails to mention that angiography, as a diagnostic procedure for acute bleeds without a CT road map can be very time consuming and frustrating. Further imaging of the extremities is reserved for the secondary survey. MRI is indicated for patients with spinal neurological deficits but not in the unstable patient.
Dominic Barron
Abstract There has been an exponential improvement in trauma imaging in terms of quality, accessibility and injury demonstration. Unfortunately the standard trauma algorithms and literature have failed to keep pace. This has resulted in very few centers utilizing imaging to its full potential, with a heavy reliance on established ATLS dogma. This article aims to illustrate how comprehensive imaging in the polytrauma patient, incorporated into these same ATLS criteria, can optimize patient care.
ATLS recommended imaging Plain radiographs There is no doubt that these remain the bread and butter of all trauma imaging. They are quick to perform, readily available, provide temporal assessment of the patient and most clinicians feel comfortable with their interpretation. Unfortunately they only provide limited information and are two-dimensional composite images of 3D structures.
Introduction Imaging in the 21st Century bears no resemblance to what was safe, achievable and practical only 10 years ago. Unfortunately most trauma treatment algorithms have not caught up with this and remain out of date, prejudiced by myth and misinformation. The aim of this article is to outline traditional imaging in trauma, illustrate what is now possible and finish by presenting an imaging algorithm appropriate for current practice.
Traditional view of trauma imaging For the past 30 years ATLS (Advanced Trauma Life Support) has been, and remains, the Gold Standard for management of the acute trauma patient.1 Therefore, this is the standard of care that all Trauma Centre’s aspire to and the basis for most trauma treatment algorithms. Standard ATLS teaching is that patients should be assessed in order of priority of life-threatening injuries. Therefore patients’ injuries should be assessed and dealt with in the following order: A e Airway þ C-spine immobilization B e Breathing C e Circulation D e Disability E e Exposure.1 Within this primary survey the only recognized radiology adjuncts are the FAST scan (Focused Assessment with Sonography for Trauma), chest and pelvic radiographs. The justification for these is that they allow the clinician to quickly identify life-threatening injuries: FAST e Intra-abdominal bleeding Chest radiograph e pneumothorax, haemothorax and mediastinal bleeding Pelvic radiograph e pelvic fractures with likely bleeding. Figure 1 50-year-old patient admitted with blunt trauma to the left chest wall. a AP CXR demonstrating at least one left rib fracture. b Axial CT image demonstrating the left anterior pneumothorax (arrow), left surgical emphysema and left posterior atelectasis.
Dominic Barron Consultant Musculoskeletal Radiologist, MRI Department, Clarendon Wing, The General Infirmary at Leeds, Great George Street, Leeds, LS1 3EX, UK.
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Pelvic radiograph This is taken to identify major pelvic injuries. The rationale for including this in the primary survey is that these fractures are strongly associated with significant bleeds. When present 85% are venous/cancellous and 15% arterial in nature. The classical teaching is that if a pelvic injury is recognized then the patient should go for surgery either with an external fixator or for pelvic packing (Figure 4). Although these remain treatment options modern imaging techniques mean that angiography and embolization should now also be considered. Extremity imaging Standard teaching is that this is part of the secondary survey. This intuitively makes sense as most life-threatening extremity injuries should be visible on direct inspection. Plain radiographs are considered adequate for this. This certainly holds true for the majority of cases but in complex injuries more detailed information can be obtained from a CT if the patient is having this as part of a trauma scan. Whole body scanogram The problem with the standard imaging algorithm is that one ends up with limited information on a patient with potentially multiple separate injuries. This is exacerbated in the obtunded patient where these will all have to be pain-stakingly located. To simplify this there are now a number of systems available that allow a whole body radiograph to be taken. Although this is inferior to standard radiographs for fine detail it does allow for a quick overview of the whole patient with the true extent of their bony injuries being made immediately available. An alternative approach is to obtain a whole body CT scanogram immediately prior to any more focused CT being performed.
Figure 2 AP CXR demonstrating enlarged, globular cardiac outline consistent with acute pericardial effusion causing tamponade. Traumatic right pleural effusion is also shown.
Chest radiograph (CXR) The purpose of this is to demonstrate pneumothoraces or mediastinal injuries. Pneumothoraces classically show up as loss of lung marking with a sharp edge demonstrating the edge of the lung. Unfortunately all major trauma patients are by definition imaged in a supine position. The free air will rise anteriorly resulting in no visible lung edge (Figure 1). Mediastinal injuries can also be difficult to assess unless there is a major bleed, as the anterior-posterior (AP) nature of the radiograph makes assessment of the mediastinum unreliable (Figures 2 and 3). Therefore, although the CXR can be useful care should be exercised in its interpretation and a negative film can be falsely reassuring.
Ultrasound Formal abdominal ultrasound has little place in the initial evaluation of the adult polytrauma patient. This is because although it is excellent at identifying fluid, even in expert hands significant organ injuries and retroperitoneal injuries can be missed. In very
Figure 3 a CXR showing marked upper mediastinal widening consistent with an aortic injury. b Axial contrast-enhanced CT image showing the large aortic dissection flap with extensive mediastinal and pleural haematoma.
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Figure 5 FAST scan of the right upper quadrant showing free fluid around the liver (arrows).
Figure 4 Pelvic XR demonstrating multiple fractures with vertical displacement of the right hemi-pelvis consistent with a vertical shear pattern of injury.
unstable patients. It is exactly this group of patients who benefit most from angiography and embolization. CT Angiography is used to provide the interventionalist with a road map of where the bleeds are, their nature and whether they would be better dealt with surgically (Figure 6). Most angiography suites are a safe environment in which to manage an unstable patient. Many are now set up as minioperating theatres, with the most modern having laminar flow theatre conditions. Angiography is well suited to dealing with defined arterial bleeds but it is of limited value where multiple bleeding sources are present or when the bleeding is mainly venous. This is the reason why CT should precede any vascular intervention as this allows an informed decision to be made regarding the most appropriate course of action.3
young children, with much smaller areas to be covered, ultrasound may be of assistance.
FAST scan (Focused Assessment with Sonography for Trauma) This is distinct from formal ultrasound in that the scan is only performed to look for free intra-peritoneal or pericardial fluid. This is very fast, reproducible and can be repeated as often as necessary to look for temporal changes. When this is present in the acute trauma patient this usually represents blood (Figure 5). Therefore a positive FAST scan is of huge diagnostic value. Unfortunately a negative scan has no value, as there can still be significant injuries that do not show up. This is particularly true of retroperitoneal injuries.
Magnetic resonance imaging (MRI) In acute polytrauma management the MRI Unit is an exceptionally hostile patient environment. All ferromagnetic metal has to be removed from the patient, MR compatible monitoring equipment is used and access is very limited. Perhaps the most important consideration is that image acquisition remains
Interventional radiology Tied in with the rapid advances in CT imaging is the change in the role of interventional radiology. This has now been recognized in the latest ATLS Student Manual (Ref 1 P122). Bizarrely, though, the manual still bans the use of CT in haemodynamically
Figure 6 30-year-old male admitted after a Road Traffic Accident with clinical evidence of bleeding. a CXR shows left sided rib fractures. b Portal venous phase CT showing splenic pseudo-aneurysm (arrowhead) and free intra-peritoneal blood (arrows). c Splenic arteriogram showing multiple pseudoaneurysms, which were then embolised.
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lengthy and as such the label “doughnut of death” can potentially still apply to this modality. The only real indications for taking an acute trauma patient into the MR Unit are for the assessment of spinal neurology, or in the obtunded patient where early spinal clearance is indicated and clinical assessment and CT have failed to provide the answer.4 This should only be done after multi-disciplinary discussion, most importantly with the anaesthetists who have a pivotal role in caring for the patient. Any trauma patient who does undergo a spinal MRI should have the whole spine imaged, such is the high incidence of multi-level injuries (Figure 7).
diagnostic value. Clearly this was unacceptable with such a poor diagnostic yield. Multi-detector spiral scanners, first introduced in 1998, have completely revolutionized imaging and have completely replaced the old single slice machines. These can carry out a whole body scan in approximately 30s generating up to 2000 high quality images. These can be reformatted into any plane necessary, with the capacity to image the patient in any phase of blood flow required. Indeed, such is the change in CT utilization that a recent multi-centre study found that integrating whole body CT into early trauma care significantly increased the probability of patient survival in patients with polytrauma.5 The standard approach to scanning a polytrauma patient is to image from the vertex to the pubic symphysis.6,7 The head is imaged on its own, usually as a volume to allow for reformats of any bony injuries. The cervical spine is then imaged next, either as part of the whole torso volume or in isolation (Figure 8). Imaging this on its own gives the best image quality as the arms can then be held down. However this then means that the torso volume includes the thyroid again with a double radiation dose to this organ.8 The other advantage to including the cervical spine in the torso volume is that arterial images of the carotid and vertebral arteries can be obtained for free with this technique.9 The chest down to the diaphragms is next imaged in the arterial phase. This is to look for major chest injuries involving
21st Century trauma imaging The main problem with all traditional imaging algorithms is that they haven’t caught up with the exponential improvement in CT technology. This is compounded by the following widely held myths: 1 Radiology is of limited use in the acute patient 2 CT is the doughnut of death 3 You cannot take a haemodynamically unstable patient into a CT scanner 4 You need a spiral scanner to do this. The reason for the widespread, and illogical, mistrust of CT scanners stems from the old single slice machines. These could take up to half an hour to generate 100 images of limited
Figure 7 Motorbike rider who crashed into a tree at 70 mph. a CXR showing multiple chest drains, ET tube, NG tube, at least one right rib fracture and a large left pleural effusion. b Axial CT image showing left sided chest drain in pleural effusion, which had chylous fluid consistent with thoracic duct injury. There is diastasis of the facet joints at this level (arrowhead) consistent with a fracture/dislocation. MRI was performed, as the patient had no sensation below the T9 level. c Sagittal Gradient Echo MRI showing cord transection, the arrowheads are the edges of the retracted cord. The very dark areas at the arrowheads are haematoma at the edges of the transected cord. d STIR sagittal image of the lower thoracic spine shows oedema in multiple vertebral bodies consistent with multi-level injury.
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Figure 8 25-year-old obtunded patient admitted after road traffic accident. a Screening lateral cervical radiograph with no obvious abnormality. b Axial CT though the upper cervical spine demonstrating multi-segmental fracture of C1.
the great vessels and the lungs. Specific review areas will be for arterial bleeds and pneumothoraces. The abdomen and pelvis are then routinely imaged in the portal venous phase of imaging. The reason for this is that liver, renal and splenic injuries are the most commonly injured structures in this region and they are best demonstrated in this phase. Once the standard volumes have been acquired routine reformats of the spine, pelvis and abdomen should be performed to aid interpretation of difficult injuries to these areas.
with these is that they may rupture, 67%.10 Both show similar imaging characteristics, a well circumscribed focal area of increased CT attenuation on arterial/PV phase. As they are vascular lesions they wash out on the delayed renal excretory phase, unlike arterial extravasation secondary to a bleed that accumulates over time. These are a particular area of interest to the interventionalist who will be keen to embolise these before they rupture.
Haemodynamically unstable patient These are the most challenging yet potentially rewarding patients to deal with. The standard teaching, as stated above, is that these patients should not go through a CT scanner and should go immediately to the operating room. Modern imaging techniques challenge this approach. CT remains the only reliable way to assess for intra-torso injuries and most importantly acute vascular bleeds. These are not always in surgically accessible regions and this explains why many laparotomies are negative in unstable patients. When active bleeding is the main clinical problem it makes sense to alter the scanning parameters to specifically look for these, as per ATLS guidance. Therefore the whole of the torso should be scanned in the arterial phase followed by portal venous phase imaging of the abdomen and pelvis. This approach allows the radiologist to differentiate between arterial and venous bleeds. Arterial bleeds will show contrast extravasation on the arterial phase imaging which increases on the portal venous phase. Venous only bleeds will only be visible on the portal venous phase imaging. This then allows for sensible utilization of interventional radiology, as there is little value in angiography if the bleeding is only venous (Figure 9).
Urinary tract injuries The kidneys are well assessed on standard protocols though the collecting systems, ureters, bladder and urethra require more focused imaging.11 Where there is a high index of suspicion for injuries to collecting systems or the ureters then a delayed scan (5 min) through this area is indicated. This allows time for the contrast to be processed through the kidneys and to start to be excreted (Figure 10). Bladder injuries can be devastating and are classically associated with pelvic injuries. The most reliable way of looking for these is to pass 300 ml of dilute contrast into the bladder via a urinary catheter if it is present. The radiologist then looks for contrast spill on the dedicated bladder CT (Figure 11). When no catheter is present due to the severity of the patient’s injuries then an alternative approach is to wait for 20 min after the initial scan and repeat it. This is however unreliable and quite rightly very unpopular with trauma teams. Urethral injuries are often overlooked in the initial assessment, as they are not life threatening, however they can cause major morbidity. If the trauma team has failed to pass a catheter during the initial treatment of the patient then there is a high likelihood of this. In this scenario the best way to assess for urethral disruption is by urethrogram. This can be done easily in the Resuscitation bay by gently passing a catheter in the external meatus and gently inflating the catheter balloon in the navicular fossa.
Pseudo-aneurysms and arterio-venous fistula These are arterial wall injuries. The rate of enlargement depends upon the strength of the pseudo-wall. The concern
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Figure 9 20-year-old patient who jumped 60 ft and was brought in haemodynamically unstable. a Axial CT of the skull showing left sided linear skull fracture. b Axial CTof the chest showing active bleeding on the left (arrow), significant consolidation on the right surgical emphysema on the right and two chest drains on the right. c Axial CT through the upper abdomen showing active bleeding from the liver (arrow) with haemoperitoneum. d Axial CT though the pelvis showing active bleeding from the fractured right acetabulum (arrowhead). The patient went for angiography with extensive embolization with a good outcome.
Contrast is then gently injected and standard plain radiographs can be taken looking for contrast extravasation. Dose According to the Ionizing Radiation (Medical Exposure) Regulations 2000,12 all imaging using ionizing radiation has to be justified. In addition to this, following the ALARA (As Low As Reasonably Achievable) principles, every investigation should be tailored to deliver the lowest dose possible that gives a diagnostic quality result. This topic deserves an article of its own, such is the complexity and controversy that surrounds it. Needless to say that underimaging is just as bad as over-imaging as for a patient to develop a radiation-induced lesion they must survive the trauma. In other words missing a major injury just to keep the dose down is as bad as over-irradiating the patient. The real key to this is to have robust local protocols showing which patients require which imaging pathway.13 The relative
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Figure 10 23-year-old female victim of a stabbing attack. Delayed axial CT image showing the extensive peri-renal haematoma (arrow) and urinary leak (arrowhead) from the major renal injury.
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Appendix 1 Acute Polytrauma Imaging Algorithm Patient admitted to Resuscitation Bay Radiology and CT immediately informed Primary survey radiographs, FAST scan performed provided these do not delay transfer to CT. Whole body scanogram if available Patient transferred to CT Haemodynamically unstable
Haemodynamically stable
Unstable protocols
Figure 11 Axial CT cystogram showing free spill of contrast out of a right bladder rupture.
Stable protocol
Defined arterial bleeds
Venous / multiple arterial bleeds
Angiography +/- embolisation
Surgical approach Whole body scan + whole body scanogram
risk has to be justifiable and there should be lee-way in the protocols to adjust for patient size, age and risk of additional injuries. This should involve the local Medical Physics department who are invaluable in ensuring radiation-efficient scanning protocols and working out the exact dose that each patient has received.
CT Complex extremity injuries Full report within the hour
Appendix 2 Integrated algorithm
Radiology trauma request
The greatest problem facing any hospital is integrating all of the above into a sensible algorithm. The variability of imaging provision, multitude of in-house prejudices, widely differing experiences and the recent exponential improvement in imaging modalities all make this difficult. The only way to sensibly approach this is to set up a multidisciplinary group whose job it is to oversee the full patients path way. Failure to engage any of the stakeholders in trauma management will inevitably lead to a failure of management, as the disenfranchised group will ignore any unilateral protocols. The most important facet of this has to be communication pathways and patient movement protocols. Put another way, who do you call, when do you call them and how do you move the patient from one location to another. Appendix 1 is a summary algorithm for the management of a polytrauma patient in a department with all imaging modalities at hand. Appendix 2 is the information that the radiology department will require to image the patient. Appendix 3 is a list of some of the factors that should be included in a standard operating procedure to ensure the safe transfer and imaging of a trauma patient.
Patient Name Date of Birth Haemodynamic stability History & findings Renal function Pregnancy status Catheter in situ Venous access, preferably the right ante-cubital fossa.
Appendix 3 Standard operating procedures Radiology notification of impending case CT readiness to accept patient Resuscitation equipment for patient Number of staff to transfer patient Pathway for patient transfer Number of medical staff needed in CT Documentation Acute report Provisional report Formal confirmed report
Summary
REFERENCES 1 ATLS student course manual. 8th edn, American College of Surgeons Committee on Trauma. 2 Chen RJ, Fu CY, Wu SC, et al. Diagnostic accuracy, biohazard safety, and cost effectiveness e the Lodox/Statscan provides a beneficial alternative for the primary evaluation of patients with multiple injuries. J Trauma 2010; 69: 826e30. 3 Zealley IA, Chakraverty S. The role of interventional radiology in trauma. BMJ 2010; 340: 356e60.
Trauma management and imaging are developing at a pace that is outstripping the recognized protocols of care. Staffing, local expertise and equipment provision varies massively between different hospitals and yet most UK centres still deal with acute trauma cases. All hospitals dealing with these challenging cases should assess what facilities they have and integrate Radiology into their Trauma Care Algorithms at a level that they can cope with. A ORTHOPAEDICS AND TRAUMA 25:2
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4 Hogan GJ, Mirvis SE, Shanmuganathan K, Scalea TM. Exclusion of unstable cervical spine injury in obtunded patients with blunt trauma; is MR imaging needed when multi-detector row CT findings are normal? Radiology 2005; 37: 106e13. 5 Huber-Wagner S, Lefering R, Qvick LM, et al. Effect of whole body CT during trauma resuscitation on survival: a multicentre study. Lancet 2009; 373: 1455e61. 6 Salim A, Sangthong B, Martin M, Brown C, Plurad D, Demetriades D. Whole body imaging in blunt multi-system trauma patients without obvious signs of injury: results of a prospective study. Arch Surg 2006; 141: 468e73. 7 Fang JF, Wong YC, Lin BC, Hsu YP, Chen MF. Usefulness of multidetector computed tomography for the initial assessment of bunt abdominal trauma patients. World J Surg 2006; 30: 176e82.
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8 Baker SR, Hsieh YH, Maldjian PD, Scanlan MT. Inadvertent thyroid irradiation in protocol-driven trauma CT: a survey of hospital ERs. Emerg Radiol 2009; 16: 203e7. 9 Sliker CW, Shanmuganathan K, Mirvis SE. Diagnosis of blunt cerebrovascular injuries with 16-MDCT: accuracy of whole-body MDCT compared with neck MDCT angiography. AJR Am J Roentgenol 2008; 190: 790e9. 10 Rosai J. Ackerman’s surgical pathology; 1996. 11 Wah TM, Spencer JA. The Role of CT in the management of adult urinary tract trauma. Clin Radiol 2001; 56: 268e77. 12 IR(ME)R. UK: Department of Health, 2000. 13 Sampson MA, Colquhoun KB, Hennessy NL. Computed tomography whole body imaging in multi-trauma: 7 years experience. Clin Radiol 2006; 61: 365e9.
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(iii) The basic science of nuclear medicine
areas in medical imaging at the present time. Many of these functional techniques have relevance to modern orthopaedic practice, and the orthopaedic surgeon should, therefore, possess some knowledge of the scope and limitations of NM modalities as applied to orthopaedic surgery. This article will describe the physical principles behind the basic techniques of NM imaging, and will then go on to demonstrate the clinical applications of NM as applied to modern orthopaedic practice.
Michael L Waller Fahmid U Chowdhury
Abstract
The physics of nuclear medicine (NM) imaging
Functional imaging techniques in nuclear medicine provide crucial diagnostic information in a variety of clinical settings that are encountered regularly in orthopaedic practice. It is important that the orthopaedic surgeon is aware of the modalities on offer and appreciates the relative strengths and limitations of these techniques. This article will describe the physical principles underlying nuclear medicine imaging with singlephoton and positron-emitting radiotracers. It will then go on to illustrate the clinical applications of these techniques as applied to pathological conditions of the bone, with particular emphasis on bone scintigraphy and hybrid imaging techniques, such as single-photon emission computed tomography/computed tomography (SPECT/CT) and positron emission tomography/computed tomography (PET/CT).
Common isotopes and radiopharmaceuticals The ideal radiopharmaceutical should be specific to the pathway of interest, possess the requisite half-life, be sterile and pyrogen free, and should emit either gamma rays suitable for gammacamera imaging or positrons suitable for PET scanning.5 Radioactive nuclei that decay by other mechanisms, producing beta-particles or alpha-particles, merely increase the radiation dose to the patient without providing signal to an external detector, and are therefore not useful as imaging tracers, although they have a role in targeted radiotherapy. Radiopharmaceuticals are regulated as medicines, and their manufacture must be carried out to GMP standards in order that they are safe to administer to patients.
Keywords bone scintigraphy; nuclear medicine; PET; PET CT; SPECT; SPECT CT
Single-photon emitting tracers: the workhorse isotope for gammacamera imaging is technetium-99m (99mTc), which has a 6-h half-life and emits gamma rays of 140 keV energy. Technetium-99m is formed by the decay of molybdenum-99 (by beta emission), which leaves the 99mTc nucleus in a long-lived excited energy state (the “m” in 99mTc stands for “metastable”). Technetium-99m nuclei subsequently lose energy by the emission of the desired 140 keV gamma ray, with a half-life of 6 h. The chemistry of technetium is not straightforward, but methods of attaching it to clinically interesting ligands have been developed, leading to a range of useful radiopharmaceuticals. The attraction of 99mTc is two-fold: (a) its nearideal imaging properties and (b) the convenience of the generator system that makes it readily available to NM departments. The halflife of 99Mo is 66 h, which means that a generator can be delivered once or twice per week, while fresh supplies of 99mTc can be eluted from it every day for the manufacture of radiopharmaceuticals for immediate use. Other radioisotopes are used for gamma-camera imaging, either when a longer half-life is required (e.g. to allow for imaging at 24 and 48 h to detect the slow accumulation of the somatostatin analogue Indium-111-octreotide), or where the ligand of interest is not amenable to labelling with 99mTc (Table 1).
Introduction Nuclear medicine (NM) provides exquisitely sensitive functional imaging techniques that utilize trace amounts of radiopharmaceuticals to study physiological processes in vivo. Improved understanding of the biological processes that occur at a cellular level has recently led to a renaissance of interest in molecular imaging, which has its basis in NM with the introduction almost half a century ago of iodine-131 (131I) for imaging the thyroid gland.1 Functional imaging achieved widespread clinical application with the ability to generate technetium-99 (99Tc) in the mid-1960s, a radiotracer that has optimal physical qualities for use in medical imaging, and now forms the basis of over 75% of all nuclear medicine studies. More recently, further resurgence in clinical interest in NM has occurred with the advent of hybrid techniques, whereby anatomical imaging in the form of computed tomography (CT) has been integrated with the functional modalities of single-photon emission computed tomography (SPECT/CT) and positron emission tomography (PET/ CT).2e4 Overall, this has led to NM being one of the major growth
Positron-emitting tracers: fluorine-18 (18F) is the most commonly used PET tracer in clinical practice. In common with most PET tracers, 18F is produced in a cyclotron. This is achieved by proton bombardment of oxygen-18 enriched water. With a half-life of 110 min, it is practical to deliver supplies of 18F-labelled radiopharmaceuticals to hospitals from a cyclotron located 1 or 2 h away, thus sharing the costs of running the cyclotron among several customers. The single most important 18F-labelled radiopharmaceutical in clinical practice today is 18F-2-fluoro-2-deoxy-D-glucose (18F-FDG or FDG), which is a non-physiological analogue of glucose. Other 18 F-labelled radiopharmaceuticals are available, but these have yet to achieve the wide clinical applicability of FDG (Table 2).
Michael L Waller MSc PhD MIPEM Consultant Medical Physicist, Department of Medical Physics and Engineering, Leeds Teaching Hospitals NHS Trust, Leeds, UK. Conflicts of interest: none. Fahmid U Chowdhury MRCP(UK) FRCR Consultant in Radiology and Nuclear Medicine, Department of Radiology and Nuclear Medicine, Leeds Teaching Hospitals NHS Trust, Leeds, UK. Conflicts of interest: none.
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photocathode
Common single-photon radiopharmaceuticals Tc-99m diphosphonates Tc-99m tetrofosmin Tc-99m mercaptoacetyltriglycine (MAG3) Tc-99m exametazime labelled leukocytes In-111 pentetreotide I-123 metaiodobenzylguanidine (mIBG)
Skeletal metabolism Myocardial perfusion Dynamic renography
typ. 500 - 1500 V d.c.
.
Infection/inflammation imaging Somatostatin receptors Neuroectodermal tumours
Output
Scintillation crystal
Photomultiplier tube
Figure 1 Schematic diagram of a basic scintillation detector. Fluorescent photons emitted by the scintillation crystal, following absorption of gamma-ray energy, stimulate emission of photoelectrons from the photomultiplier tube’s photocathode, which are accelerated between the dynodes of the PMT generating a measurable charge pulse.
Table 1
Imaging principles and technology There are two distinct modes of NM imaging: (a) single-photon emission imaging with a gamma camera and (b) positron emission tomography (PET) which is achieved with a PET scanner. The similarities of the two techniques are, in fact, greater than their technological differences. Both non-invasively produce images of the biodistribution of an administered radioactive tracer.
the late 1950s, although camera performance has improved substantially over the years due to advances in electronic technology.6 Optimized for imaging 140 keV photons, a detector is constructed around a 9 mm thick, single crystal of sodium iodide doped with trace amounts of thallium, NaI (Tl), typically providing an imaging area of 50 cm 40 cm. A close-packed array of PMTs, optically coupled to the back of the NaI (Tl) crystal collects the resulting scintillation light (Figure 2). The
The life history of a gamma ray: from the point of emission, a gamma ray may travel straight out of the patient. However, it may be scattered (the Compton Effect), resulting in a lowerenergy gamma ray travelling in a different direction from the original, or it may be totally absorbed (either by multiple Compton scatters, or by the photo-electric effect). Although NM detectors are energy selective, it is not practicable to reject all scattered photons, hence the resulting image will, to some extent, misrepresent the distribution of tracer in the patient, because of scattered photons seeming to have originated from somewhere other than their true point of emission. Scatter and attenuation are key confounding factors affecting the quantitative accuracy of NM images, and these effects can be corrected for more accurately in PET than in gamma-camera imaging. Detecting gamma rays: most NM imaging systems are based on scintillation detectors (Figure 1). These use inorganic crystals that absorb gamma rays and then fluoresce, producing a shower of visible or ultraviolet photons. The fluorescent photon shower is converted into an electrical pulse by optically coupling the crystal to a photomultiplier tube (PMT). The magnitude of the electrical pulse is proportional to the gamma-ray energy absorbed by the crystal. Gamma-camera imaging: the essential features of the gamma camera have changed little since it was developed by Anger in
PET radiopharmaceuticals F-18-2-fluoro-2-deoxy-glucose (FDG) F-18 fluoride F-18-choline F-18-MISO Ga-68-DOTATATE
Glucose metabolism Skeletal metabolism Prostate malignancy Hypoxia imaging Somatostatin receptors
Figure 2 InfiniaÔ dual-head gamma camera with HawkeyeÔ CT (courtesy of GE Healthcare Ltd.), with a generalized schematic diagram of the principal components of a gamma-camera detector. The collimation process will allow ga to reach the scintillation crystal, while gb is rejected.
Table 2
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location in the crystal at which the gamma ray releases its energy is determined to within 2e3 mm by computing the centroid (“centre-of-gravity”) of the signals from the cluster of PMTs around the point of interaction, each of which collects a share of the scintillation photon shower. Image formation is achieved by the use of a lead (sometimes tungsten) collimator. It provides an array of holes that allow gamma rays moving parallel to the axis of the holes to reach the crystal, while the septa between the holes absorb gamma rays travelling at other angles. The collimator thus creates a one-toone correspondence between locations on the crystal and points in the plane of the patient facing the camera. The price paid is the huge inefficiency of the collimation process, which rejects 99.99% of the gamma rays emitted. In the last few years some progress has been made to address this by the use of multiple pin-hole imaging systems, which are inherently more sensitive (reducing image acquisition times by a factor of four or more), but require extensive post-acquisition computation to reconstruct images. To date this approach has been realized for cardiac and brain imaging, which only require a small field of view.7,8
opposite directions, although the imaging process assumes that they do and hence there is an inherent uncertainty in locating the point of annihilation of a few millimetres in magnitude. Furthermore the motion of a positron separates the point of emission (where the tracer has been taken up) from the point of annihilation (where it appears to have been taken up in the image). Even the current state-of-the-art PET scanners can, therefore, only achieve a spatial resolution of just less than 3 mm.9 PET imaging: a PET scanner is constructed of rings of small scintillation detectors (Figure 4). The crystals are 2e3 mm square on the side that faces the patient, but 25e30 mm in the radial direction to provide a high probability of stopping a 511 keV gamma ray. Crystals are made from high-density, high-atomic number materials, e.g. lutetium orthosilicate, also to maximize stopping power. Current systems typically have around 25 adjacent rings to give an axial field of view of about 15 cm. A robotically controlled bed allows the patients to be moved through the field of view, building up a ‘half-body’ or whole-body scan, as required. Coincidence detection: detection of the back-to-back pair allows a line through the patient to be defined along which the annihilation occurred, without the need for a collimator. This is a major advantage over the gamma camera in terms of detection efficiency. The PET scanner electronics are designed to identify pairs of gamma rays that are detected within a timing window set to about 10 ns. Such coincident pairs are assumed to have come from the same positron annihilation. However, a proportion will actually be gamma rays arising from separate annihilations. The image reconstruction software must correct for the presence of these so-called “accidental” or “random” coincidences, as well as correcting for the effects of scatter and attenuation.
Single-photon emission computed tomography (SPECT): the gamma camera is a planar imaging device, but fully threedimensional (3D) images can be produced by rotating the cameras around the patient, taking a set of images called “projections”. The reconstruction of the 3-D slices is strongly analogous to the reconstruction of X-ray CT slices. Integrated SPECT/CT: since the late 1990s, hybrid imaging cameras have been available that combine a dual-headed gamma camera with low-dose (and increasingly, full multidetector) CT. This allows sequential imaging with SPECT and CT with the patient lying in the same position, thereby allowing fusion of anatomical images with functional NM images, providing increased diagnostic accuracy. The life history of a positron: the positron is a positively charged electron that cannot penetrate more than a few millimetres in tissue, but when it collides with a negatively charged electron, it ‘annihilates’ and produces two high-energy (511 keV) gamma rays that travel essentially in opposite directions (“a back-to-back pair”) (Figure 3). These annihilation photons can be detected outside the body in a ring of detectors within a PET scanner. The photons of the “back-to-back” pair do not move in exactly
e-
F W H M ~ 0.5 O 1- 4 mm e+
Figure 4 Discovery 690 PET/CT scanner (courtesy of GE Healthcare Ltd.) with superposed schematic indicating one of the multiple rings of small scintillation crystals that detect “back-to-back” pairs of 511 keV photons arising from positron annihilation.
Figure 3 Schematic representation of the “life history” of a positron, from emission to annihilation with the subsequent creation of a (nearly) “backto-back” pair of gamma rays.
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Integrated PET/CT and PET/magnetic resonance (MR): the diagnostic advantages of co-registering a PET scan with CT (similar to SPECT/CT) acquired while the patient is still lying in the same position, compared with a PET-only investigation, are so overwhelming that it is no longer possible to purchase a PET-only scanner. Currently, the basic PET/CT acquisition involves a CT scan of fairly low radiation dose, which is adequate to provide anatomic localization of PET positive functional abnormalities and also to facilitate correction for gamma-ray attenuation. However, there is an increasing trend towards using the full diagnostic capabilities of the CT scan, including the use of imaging contrast agents, to obviate the need for separate CT studies. The first commercially available PET/MR scanner has just been launched. In theory, this is an attractive proposition due to the superior soft-tissue discrimination afforded by MR. The precise clinical applications of integrated PET/MR, however, are yet to be established.
contrast resolution and more accurate localization of lesions (especially when performed on an integrated SPECT/CT camera) and is particularly useful in the axial skeleton. If a ‘dual-phase’ bone scan is indicated, i.e. if the clinical problem is localized such as suspected fracture or osteomyelitis, a ‘blood pool’ or soft-tissue phase acquisition is performed at 5e10 min after injection, followed by a delayed or ‘crystal’ phase at 2e4 h. Any condition that is accompanied by hyperaemia will show increased uptake on the blood pool phase. The traditional ‘three-phase’ bone scan, which incorporates an initial dynamic ‘vascular’ phase as the tracer is injected, is no longer favoured in many nuclear medicine departments, as this phase adds little additional diagnostic information. Uptake of MDP depends on several factors, including (1) nonlinear relationship with blood flow and vascularity, (2) active bone turnover and osteoblastic activity and (3) incompletely understood local factors affecting calcium/phosphate deposition and intracellular calcium flux. Consequently, most active osseous processes, including tumour, infection, trauma, arthropathy, metabolic bone disease and disorders of bone growth/development, such as Paget’s disease and fibrous dysplasia, will show increased tracer uptake on a bone scan. Therefore, although the technique is highly sensitive, specificity is more limited, but this can be augmented through ‘pattern-recognition’ by an experienced nuclear medicine reporter, judicious use of SPECT and SPECT/CT, and careful correlation with clinical findings and other available imaging, including plain radiography, CT and MR.
Clinical applications of bone scintigraphy Technique Functional evaluation of pathological conditions of bone can be performed with a high level of sensitivity using 99Tc-labelled diphosphonates, which are analogues of inorganic pyrophosphate that bind avidly to hydroxyapatite crystals and become incorporated into sites of active bone turnover. The most commonly used diphosphonates are methylene diphosphonate (MDP) and hydroxymethylene diphosphonate (HDP), the latter having some advantages of more rapid blood clearance and greater bone affinity.10 There are several routine clinical indications for bone scintigraphy (Table 3). About 600e800 MBq of activity is injected into an adult patient (the higher doses are required for SPECT imaging). In paediatric patients weighing less than 70 kg, the dose has to be scaled according to the child’s body weight, with a minimum injected activity of 40 MBq.11 An uptake period of 2e4 h is required for adequate target-to-background uptake within the skeleton. The patient has to be well hydrated and is encouraged to void frequently during the uptake period in order to reduce unnecessary dose to the renal tract, which is the principal route of elimination of the tracer. Imaging is preferably performed using a whole-body technique; multiple overlapping images or a continuous ‘sweep’ with anterior and posterior views are obtained in parallel. Single ‘spot’ views of areas of interest can also be performed. A high-resolution collimator is used to strike an optimum balance between image quality and imaging time. SPECT acquisitions add to the duration of imaging, but offer increased
Physiological uptake and artefacts Normal distribution of tracer in the skeleton is usually symmetrical about the midline (Figure 5). Low-grade uptake is often seen at the shoulder joints, at the SI joints (due to weight bearing) and at sites of muscle insertion and normal muscular stress, e.g. at the deltoid and tibial tuberosities, inferior tips of the scapulae and greater trochanters. Calcified costal cartilage in the elderly may give rise to uptake in the anterior thoracic cage, which can often be slightly asymmetric. Skull uptake can be highly variable, especially at the extremes of age, with diffuse calvarial uptake not infrequently encountered as a normal variant in elderly patients. This may also imply benign conditions such as hyperostosis frontalis. Uptake at the manubriosternal joint and a welldefined midline photopaenic area in the lower sternum can also be seen as normal variants, and should not be over-called as pathological lesions. The dorsal kyphosis and lumbar lordosis can be readily recognized by slightly more apparent uptake in the dorsal spine compared to the lumbar area. In the lower limbs, patellar uptake is a common finding in asymptomatic patients. Physiological uptake at the unfused growth plate is an expected finding in children, and this is usually symmetrical. Artefacts on bone scans may result from various sources, including camera faults, dissociation of technetium from the diphosphonate moiety (with consequent free pertechnetate trapped in the thyroid, salivary glands and gastric mucosa), a paravenous injection with consequent tracer extravasation, urinary contaminant and bladder artefacts. Apparent photopaenic areas may arise due to overlying metal artefact, e.g. coins or jewellery. Careful patient preparation, direct correlation at the time of the study and additional views if required can ameliorate the clinical impact of such artefacts.
Clinical indications for bone scintigraphy Suspected bone metastases Radiographic lesion C Is it significant/active? C Is it solitary or are there multiple lesions? Persistent bony pain e normal radiography Acute symptoms e normal radiography (e.g. occult fracture) Assessment of joint disease, especially prosthetic joints Table 3
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Figure 5 Normal Tc-HDP bone scan. Anterior and posterior planar wholebody views showing normal pattern of skeletal uptake.
Figure 6 Bone scan (anterior and posterior views) in a patient with prostate cancer and multiple bone metastases. There is prominent cardiac uptake (arrow). The patient was known to have a dilated cardiomyopathy.
Extra-osseous tracer uptake Extra-osseous tracer uptake on a bone scan may or may not have clinical significance.12 It is, however, important to be aware of some of the potential causes of such findings. Approximately 50% of injected activity is cleared by the urinary tract 2e3 h following injection of diphosphonate compounds. The presence of activity in the renal tract should be scrutinized carefully. Loss of renal uptake may signify poor renal function, in which case the background activity may be increased resulting in a poor quality bone scan. This could also be an indirect clue to the presence of diffuse skeletal abnormality (see later). Unilateral loss of renal uptake may be due to a non-functioning or absent kidney. In contrast, diffusely increased parenchymal renal uptake is usually associated with chemotherapy, but may also result from any cause of hypercalcaemia or hypercalciuria. Muscle and/or soft-tissue uptake may be seen in rhambdomyolysis, myositis ossificans or as a consequence of soft-tissue oedema, infection (e.g. cellulitis) or in limb paralysis. Tracer uptake in solid abdominal organs can be associated with tissue infarction, parenchymal calcification or the presence of metastatic tumour. Diffuse splenic uptake has been described in a variety of haematological disorders, and diffuse abdominal activity may reflect the presence of ascites. Diffuse uptake in the stomach can be associated with hypercalcaemic states. Pulmonary parenchymal uptake can be seen in diffuse lung processes
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such as radiation-induced pneumonitis. Breast uptake may be physiological or may arise as a non-specific finding due to both benign and malignant conditions. In males, it is frequently seen with gynaecomastia in patients with prostatic cancer on hormone treatment. Cardiac uptake is associated with myocardial infarction, left ventricular aneurysm, cardiac sarcoidosis or amyloidosis and malignant pericardial effusions (Figure 6). Bone tumours Primary bone tumours: although many benign lesions of the bone show no increase in activity on a bone scan, some benign lesions, e.g. aneurysmal bone cysts and osteochondroma, may demonstrate a variable degree of uptake. Lesions such as bone infarcts, bone cysts and enchondromas are much better characterized using plain radiography, with bone scans having little role in such conditions. Bone scintigraphy has an important role, however, in detection of osteoid osteoma, which usually demonstrates an intense focus of uptake within the osteoblastic nidus. A negative bone scan virtually excludes the diagnosis. Aggressive primary bone malignancy, including osteosarcoma and Ewing’s sarcoma, are almost always extremely avid on bone scintigraphy. Increased uptake on blood pool phase imaging reflects the hypervascularity of these tumours, and delayed
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images will show marked intensification of tracer uptake. There may be some heterogeneity in uptake (including areas of photopaenia) related to tumour necrosis, particularly in osteosarcoma. The definition of primary tumour size and extent can be misleading on bone scintigraphy due to poorly defined margins, distortion of the bony outline and ‘blooming’ of tracer uptake as a result of soft-tissue and marrow hyperaemia. MRI is the primary imaging modality for providing local staging of primary bone tumours. It can provide information about the extent of tumour involvement, identify skip lesions and show the relationship of tumour to neurovascular structures. The principal role of scintigraphy is in identifying metastatic disease once a primary bone tumour has been identified. Bone metastases are detected in 2e11%, with higher rates associated with Ewing’s sarcoma (Figure 7).13
30e75% are required to detect lesions radiographically. Bone scans are particularly sensitive at detecting osteoblastic or sclerotic metastases, from prostate, lung and breast primary tumours. As 90% of bone metastases arise within red marrow, they are most frequently demonstrated within the axial skeleton (Figure 8). The presence of multiple focal areas of increased uptake, varying in size, morphology and intensity, with a random distribution in a high-risk cancer patient seldom leads to any diagnostic dilemma. When there is disseminated skeletal involvement, the typical ‘metastatic super scan’ appearance may be seen, with heterogeneous uptake throughout the skeleton, with a corresponding reduction in activity within the renal tract, background soft tissues and within the calvarium (Figure 9). However, difficulty in interpretation may arise when dealing with solitary lesions (Figure 10). Studying the pattern of uptake in such cases may be helpful. For instance, a solitary rib lesion in a patient with known cancer has only a 10% probability of being
Secondary bone tumours or metastases: detection of osseous metastases is one of the most common clinical indications for a bone scan. Bone scintigraphy is a readily available, whole-body examination that is significantly more sensitive than plain radiography at detecting bone metastases.14 This is largely attributable to the fact that scintigraphy can detect a change in bone turnover of as little as 5e10%, whereas bone density changes of
Figure 7 Bone scan (anterior and posterior views) in a patient with known osteosarcoma of the left radius (large arrow). There is extensive ‘blooming’ artefact due to soft-tissue hyperaemia, which over-represents the size of the primary tumour. A solitary bone metastasis was detected in the L1 vertebra (smaller arrow). Note the area of tracer extravasation at the injection site in the right antecubital fossa which has been digitally masked (arrowhead ).
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Figure 8 Bone scan (anterior and posterior views) in a patient with widespread bone metastases from a prostatic primary.
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undetected small lesions may become visible due to the healing and reparative process, and this may be misinterpreted as disease progression.15 This phenomenon usually occurs within 3 months of therapy, and subsides by 6 months, and is most commonly seen in breast cancer patients. Bone scintigraphy is less sensitive in the detection of osteolytic or rapidly destructive lesions from renal, thyroid and breast cancer, when there may only be relatively subtle circumferential uptake around a photopaenic lesion, representing a peripheral reparative process. It is also the case that the small osteolytic lesions that are classically seen in multiple myeloma are frequently undetectable at bone scintigraphy; hence bone scan is not considered a standard investigation for patients with myeloma. Other imaging modalities, including cross-sectional imaging with CT and MR, may provide additional information in such cases. A recent comparison of bone scan and MR in detection of bone metastases from renal cancer, for instance, showed that MR was significantly more sensitive (94% vs. 62%).16 Overall, therefore, the sensitivity of bone scintigraphy for detecting metastatic osseous disease is in the region of 62e100%, with a specificity of 78e100%.14 The role of PET/CT with 18F-FDG and 18 F-fluoride will be discussed later. It is reasonable to conclude, however, that for most cancer patients, bone scintigraphy remains a reliable initial screening test for bone metastases, although it is important to appreciate the limitations of the technique, and revert to other imaging modalities when required. Trauma Bone scintigraphy has a valuable role in the assessment of skeletal trauma. Plain radiographs of course remain the initial technique of choice, but scintigraphy has an extremely useful role in detecting radiographically occult bony injury and insufficiency fractures. The technique has very good sensitivity and a particularly high negative predictive value for acute bone trauma. This is a consequence of the fact that preferential tracer uptake can be seen at sites of acute fracture within 24 h after injury in 95% and within 7 days in 100%. Dual-phase bone scans are mandatory in this situation, as acute fractures will manifest increased tracer uptake on the blood pool phase, followed by marked intensification of activity on the standard delayed view (Figure 12). In contrast, ‘bone bruising’, which represents trabecular microfractures but with no overt cortical disruption, usually shows increased uptake on only the delayed images. The acute phase of intense uptake can be demonstrated for 2e4 weeks following fracture in most cases, and more moderate uptake usually persists for a further 2e3 months. Achieving normalization of uptake at the fracture site takes a highly variable course, which can last up to 2e3 years in some cases, and may never return to normal in those with mal-union or abnormal healing. In general, however, normalization occurs within 8e12 months in the majority, with rib and long bone lesions healing more rapidly than spinal fractures.10 Stress and insufficiency fractures can also be imaged with high sensitivity with bone scan. Classical patterns of uptake can help to differentiate tibial stress fractures from shin splints (medial tibial stress syndrome). Shin splints classically show low to moderate grade, symmetric tracer uptake in the distal posteromedial tibial cortex on delayed images only, with normal blood pool distribution, whereas stress fractures of the tibia tend to be much more
Figure 9 Bone scan (anterior and posterior views) showing the typical metastatic ‘super scan’ appearance, indicating disseminated bone metastases. There is diffuse and heterogeneous uptake throughout the axial and proximal appendicular skeleton, with a relative reduction in uptake within the background soft tissues, calvarium and renal tract. In particular, note the non-visualization of the kidneys.
metastatic and is much more likely to be post-traumatic in nature, particularly if the uptake is very focal rather than invading along the long axis of the rib. Interpretative difficulty may also be experienced when there is co-existent benign but active bone pathology, particularly in elderly patients, e.g. a combination of degenerative disease and metastases in the vertebral column. More accurate localization of vertebral lesions can be extremely helpful, as involvement of the central vertebral body or pedicles are much more likely to be metastatic, rather than uptake at the anterolateral or posterolateral areas of the vertebra which usually represents degenerative discogenic or facet joint disease, respectively. The use of SPECT/CT in assessing vertebral lesions has been shown to increase reporter confidence significantly in this setting (Figure 11). Other strategies to aid diagnosis of an equivocal lesion would include performing other focused imaging of the area in question, e.g. plain radiographs, CT or MR, or performing an interval bone scan to re-evaluate the lesion. Serial bone scanning for assessing response after treatment can be hindered by the ‘flare response’, whereby bone metastases may become more avid or previously
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Figure 10 a Bone scan (anterior and posterior views) in a patient with prostate cancer shows a solitary bone abnormality at T11. b AP radiograph of the thoraco-lumbar spine shows diffuse osteosclerosis of T11 consistent with a bone metastasis.
Figure 11 a Bone scan (anterior and posterior views) in a patient with thyroid cancer shows a subtle focus of increased uptake in the left side of L3. b SPECT/CT was performed to afford better localization, confirming that the uptake was in the left pedicle of L3. This was considered suspicious for a bone metastasis and subsequently confirmed as such on follow-up imaging.
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osteoblastic response in such patients. For example, in a series of 160 cases, false-negative scans were obtained in four patients, all of these occurring in patients over 70 years of age.17 Delayed/ repeat imaging after 7 days may be helpful in cases where there is a high clinical index of suspicion. In assessing suspected scaphoid fracture, it is again important to avoid premature scanning, i.e. within 2 days, as false-negative results may be obtained at this stage. When there is scintigraphic abnormality, precise localization may be challenging due to the poor spatial resolution of scintigraphy. Careful correlation with plain radiographs, crosssectional imaging with CT or MR or the use of high-quality (i.e. multidetector) CT in a SPECT/CT scanner will often prove helpful in this situation. Imaging fractures in the spine can be complicated by poor anatomic localization on planar views, and therefore SPECT and SPECT/CT imaging should be routinely performed in such circumstances. It is worthwhile appreciating that pars fractures, usually affecting L5 and L4, can often be distinguished from degenerative facet joint arthropathy by the fact that facet joints lie on the same plane as the intervertebral disc on sagittal images, whereas the pars inter articularis is located more caudally and just behind the vertebral body. Imaging of traumatic lesions close to the highly active epiphyseal plate in the immature skeleton can also prove challenging on scintigraphy. A lack of symmetry in growth plate uptake may indicate the presence of a Salter-Harris injury, but the findings can be rather non-specific as there is a differential diagnosis for growth plate abnormalities, including trauma, infection, metabolic disease and slipped upper femoral epiphysis (SUFE). Scintigraphy has a limited role in imaging complicated fracture healing. There is some experience to show that bone scan may be useful in confirming atrophic non-union or pseudarthrosis, where the classical appearances show reduced uptake or a frankly photopaenic area at the site of non-union, but beyond this the usefulness of scintigraphy in this context is questionable. Bone scan is also of limited use in evaluating soft-tissue injury.
Figure 12 Dual-phase bone scan of the hands and wrists in a patient who had a fall on the outstretched hand 10 days prior to the scan with normal radiographs. There is abnormal tracer uptake on both blood pool and delayed views near the base of the right index finger metacarpal consistent with a radiographically occult fracture.
focal, asymmetric and show uptake on both blood pool and delayed images. Other fractures that can be challenging to depict on plain radiography, such as stress fractures in the tarsal or metatarsal bones or subchondral fractures of the knee, can be also detected with great sensitivity with bone scintigraphy (Figure 13). The typical appearance of a fusiform area of intense uptake within the metatarsal shaft, usually affecting the 2nd or 3rd metatarsal, is virtually pathognomic for metatarsal stress fracture. Similarly, the classical ‘H’ or ‘Honda’ sign, where there is an intense horizontal band of uptake across the body of the sacrum with adjacent vertically orientated uptake at the lateral margins along the SI joints, is highly suggestive of sacral insufficiency fracture, although some caution has to be exercised in patients with possible metastatic disease (Figure 14). If in doubt, thin-section CT can often provide confirmation of the diagnosis. It is important, however, to be aware of some of the limitations of bone scintigraphy in the context of trauma. Hip fractures in the elderly may occasionally fail to undergo detection with scintigraphy, partly due to a combination of poor vascularity and a weak
Figure 13 Bone scan (planar anterior view of the lower limbs with additional SPECT/CT images) in an active sportsman with shin pain. There is linear uptake along the cortical margins of the tibia bilaterally, consistent with ‘shin splints’. In addition, there is an abnormal area of moderate tracer uptake in the subarticular surface of the right tibia (see SPECT/CT localization), which was felt to be consistent with bone bruising or trabecular microfractures. The patient was treated conservatively.
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Figure 14 Bone scan (anterior and posterior views) in an elderly woman with pelvic pain show the typical scintigraphic finding of the ‘Honda’ sign of sacral insufficiency fracture (arrow). Note also the presence of a left inferior pubic ramus fracture (arrowhead ) and multiple rib fractures. The patient was found to have osteoporosis.
Although secondary enthesopathic changes in the bone may be detectable at the site of injury, other modalities such as highfrequency ultrasound and MR can demonstrate the nature and extent of soft-tissue injuries with much greater clarity. Disorders of bone metabolism and development Bone scintigraphy is a valuable imaging tool in the evaluation of the entire skeleton in disorders of bone metabolism and development. Important conditions in this category include Paget’s disease, fibrous dysplasia, osteomalacia and renal osteodystrophy. Paget’s disease: it is a disorder of bone turnover and remodelling first described by the British surgeon Sir James Paget in 1877. Bone involvement is polyostotic in the majority (70e90%), and scintigraphy offers a reliable and sensitive tool for demonstrating the extent and activity of disease.1 The axial skeleton is most commonly involved, followed by the long bones, with more rare sites of disease including the ribs, fibula, patella and small bones of the hands and feet. Appendicular involvement tends to be unilateral. The scintigraphic features are quite characteristic, showing hyperaemia and intense uptake of tracer throughout most, if not all, of the involved bone with evidence of remodeling in the later stages of the disease process. Certain well-recognized scintigraphic patterns have been described at specific sites, e.g. ‘Mickey Mouse’ sign in the vertebra and ‘Abraham Lincoln’ sign in the mandible (Figure 15). The scintigraphic diagnosis is often straightforward, but occasionally in the context of malignancy, especially prostate cancer, some caution should be applied as metastatic disease may mimic Paget’s, and in these circumstances plain films of the affected areas can provide very useful additional information. Scintigraphy is less reliable at demonstrating secondary osteosarcoma arising within Pagetic bone, which can develop in
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Figure 15 Bone scan (anterior and posterior views) shows Paget’s disease of the mandible (‘Abraham Lincoln’ sign) and of the left hemipelvis. The involvement of the whole bone is a typical feature of Paget’s disease.
1e5% of these patients, as there may be only subtle heterogeneity in uptake or a relative photopaenic defect at the site of the tumour, which may be difficult to appreciate on the scintigram. Serial bone scans may be used to assess response to therapy with bisphosphonates, but this can probably be done more costeffectively through evaluation of symptomatic and biochemical response (i.e. serum alkaline phosphatase and urinary hydroxyproline). Fibrous dysplasia: this is a sporadic condition that is usually monostotic in distribution (70e80%) and is either detected due to complication such as fracture or as an incidental asymptomatic finding in young adults.1 The underlying cellular abnormality constitutes a disorder of osteoblast maturation.
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Commonly involved areas include the ribs, the craniofacial bones and long bones. The role of scintigraphy is principally in detecting polyostotic involvement and demonstrating disease activity. The polyostotic form presents earlier, is more frequently symptomatic and may be seen in McCuneeAlbright syndrome, which is also associated with cafe-au-lait spots, precocious puberty and hyperthyroidism. The typical scintigraphic appearance of fibrous dysplasia is of increased hyperaemia and moderate to markedly avid tracer uptake within the involved bone, which is of abnormal shape and morphology (Figure 16).
axial skeleton and long bones, with a corresponding reduction in uptake within the background soft tissues and renal tract. In contradistinction to the metastatic ‘super scan’, however, there is usually an increase in calvarial, sternal and mandibular uptake, prominence of the costochondral junctions and the skeletal uptake is generally more homogeneous and uniform.18 Osteomalacia is also characterized by the presence of focal uptake at sites of pseudofracture (Looser’s zones) (Figure 17). Renal osteodystrophy: in patients with renal failure, a constellation of features including secondary hyperparathyroidism, osteomalacia and osteosclerosis constitutes the syndrome of renal osteodystrophy. Scintigraphically, the more severe form of the disorder can give rise to a metabolic ‘super scan’ appearance, with some characteristic features including prominent uptake around the orbits, within the sternum (with a stripe-like appearance) and in the distal long bones (Figure 18).
Osteomalacia: characterized by abnormal accumulation of uncalcified osteoid with consequent bone softening as a result of lack of dietary calcium, osteomalacia can often be overlooked in patients with generalized bone pain and an unexplained elevation of serum alkaline phosphatase. In common with other metabolic bone disorders, such as hyperparathyroidism, pseudohyperparathyroidism and hypervitaminosis D, bone scintigraphy may show the features of a metabolic ‘super scan’, which is typified by a generalized increase in uptake throughout the
Arthritis Bone scintigraphy is a sensitive test for the demonstration of active sites of inflammatory and non-inflammatory arthropathy. Uptake occurs at hyperaemic sites in the juxta-articular bone due to active synovitis, as well as in areas of increased bone turnover where the synovio-chondral interface has been breached by the arthritic process. Characteristic sites of involvement for different types of arthropathy can be demonstrated on bone scans, but scintigraphy lacks specificity and has to be considered in correlation with the clinical, biochemical and plain radiographic findings. It is also not an entirely reliable method of demonstrating the degree of severity of an arthropathy. As a result, scintigraphy is of limited value in assessment of joint disease. Where it is of clinical value, however, is in the evaluation of patients with unexplained arthralgia, as a normal bone scan has a high negative predictive value and effectively excludes an active polyarthropathy. Vascular conditions As discussed previously, vascular integrity is a crucial requisite for extraction and uptake of diphosphonate tracers into bone. It is not surprising, therefore, that increases in regional perfusion and tissue permeability that accompany hyperaemic conditions can show increased uptake on bone scan. Similarly, interruption of blood supply will lead to reduction in tracer delivery and uptake. The scintigraphic features of two important vascular conditions need to be considered in this section. Avascular necrosis (AVN): it is well recognized that due to poor provision of collateral vascular supply, certain bones are at high risk of avascular necrosis (AVN), e.g. the femoral head, scaphoid, navicular and lunate. The scintigraphic findings depend on the time from the onset of AVN.19 Within 24 h, there is often a non-specific hyperaemic increase in tracer uptake. This is followed by the demonstration of a photopaenic defect at 24e72 h, which may be accompanied by a circumferential rim of uptake at the peripheral reactive margin of the necrotic bone (‘doughnut sign’) (Figure 19). Beyond 72 h, there is gradual bone reparation and the migration of active osteoblasts into the affected bone causes a moderate to markedly avid and nonspecific increase in tracer uptake in the affected area. This
Figure 16 Bone scan (anterior and posterior views) shows diffuse and heterogeneous bone uptake throughout with remodelling deformity and loss of normal bone shape and contours. Note the diffuse rib and skull base abnormality in addition to the long bone findings. The patient had polyostotic fibrous dysplasia (McCuneeAlbright syndrome).
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Figure 17 a Bone scan (anterior and posterior views) in a middle-aged woman with non-specific bone pain and elevated alkaline phosphatase. There is prominent uptake along the costochondral junctions and focal abnormality in the right inferior pubic ramus (arrow), anterior end of the left 1st rib and in the left medial tibial plateau. b AP radiograph of the pelvis shows the typical appearance of a ‘pseudo-fracture’ or Looser’s zone at the right inferior pubic ramus. The patient was subsequently confirmed to have osteomalacia.
Figure 18 a Bone scan (anterior and posterior views) in a patient with a renal transplant in the right iliac fossa (arrow) and hypercalcaemia. Note the generalized increase in tracer uptake throughout the skeleton, in particular around the metaphyseal regions of the long bones. Features are typical of renal osteodystrophy. There was a particularly conspicuous focus of uptake in the medial left tibial plateau, where the patient was symptomatic. b MR (STIR coronal images) shows bilateral medial tibial stress fractures.
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Infection Infection of cortical bone and/or bone marrow (osteomyelitis) typically spreads haematogenously, with preferential localization to the metaphyses of long bones in children and to the vertebral column and pelvis in adults. Other modes of spread include contiguous bone involvement or implantation at surgery. Scintigraphy with diphosphonate tracers is a useful screening tool for bone infection, with a high sensitivity of 90e95%.1 Typically, an area of bone infection will become positive on a bone scan within 2e3 days, whereas radiographic changes take a minimum of 10e14 days to develop. On blood pool imaging, there is early hyperaemia with marked intensification of uptake on delayed images of a dual-phase study. This can be differentiated from cellulitis or soft-tissue infection, where there is also initial hyperaemia, but this is followed by gradual reduction of intensity on delayed phases. Specific situations where bone scan is of lower accuracy include neonatal osteomyelitis and the neuropathic foot. It should be reiterated that bone scintigraphy lacks overall specificity and, therefore, other agents have to be utilized to confirm or refute the diagnosis of osteomyelitis when faced with a positive bone scan and a high clinical index of suspicion for infection. The gold-standard nuclear medicine technique to localize infection is 99Tc-exametazime (HMPAO, Hexamethylpropyleneamine Oxime, CeretecÒ) labelled leucocyte or white cell imaging.21 HMPAO is a lipophilic compound that penetrates the cell membrane and is retained intracellularly within the labelled leucocyte. This is a labour-intensive process that involves extracting white cells from 50 ml of the patient’s venous blood, labelling them with 200 MBq of 99Tc-HMPAO in vitro, and then reinjecting them back into the patient within 2 h. The margination, distribution and eventual localization of the labelled leucocytes can then be imaged over a 24-h period. Sites of physiological uptake include the spleen, liver, GI tract (after 2e3 h), GU tract and normal bone marrow. The technique has a sensitivity of 84e89% for detecting bone infection. Accuracy is more limited in two common clinical scenarios: firstly, in the context of spinal infection, as this often causes a non-specific area of photopaenia on white cell scans, leading to false-negative findings, and secondly, when prosthetic joints are being evaluated, as the redistribution of marrow around the prosthesis can cause falsepositive uptake. Alternative tracers such as 67Ga (gallium-67) citrate have been shown to have better utility than labelled leucocytes in evaluating spinal infection, but this is an inconvenient tracer for routine clinical use due to high radiation dose, requirement for delayed imaging and poor image quality. It is reasonable to conclude that MR with gadolinium-enhancement is a more convenient, reliable and conventional investigation for patients with suspected spinal infection. For imaging of prosthetic joint complication, however, nuclear medicine has much to offer, but some modification of technique is required and this warrants specific discussion in the following section.
Figure 19 Bone scan (anterior and posterior views) in a patient with fractured right neck of femur 72 h prior to the scan. There is low-grade uptake at the fracture site with a photopaenic defect in the right femoral head consistent with avascular necrosis (AVN).
sequence of events has been most reliably demonstrated in AVN of the hip. Reflex sympathetic dystrophy (RSD): synonymously referred to as complex regional pain syndrome, this is a poorly understood condition that may arise as a result of trauma, immobilization or occur spontaneously.20 The clinical syndrome incorporates a constellation of symptoms in the affected limb, including pain, swelling, neurological deficit and vasomotor/trophic soft-tissue changes. Dual-phase bone scintigraphy can assist in making the diagnosis. The blood pool phase classically demonstrates generalized hyperaemia of the affected limb, which can last for up to 20 weeks following the precipitating injury. In a minority of cases, there may actually be a paradoxical ‘vasospastic’ appearance with reduction in blood flow/blood pool uptake. The delayed phase of the bone scan typically shows moderate and diffuse increase in activity within the limb accompanied by conspicuous periarticular uptake within the joints of the affected extremity. The latter finding has been shown to be particularly specific for the diagnosis of RSD.1
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Evaluation of prosthetic joints: advances in technique and hardware over the last 50 years have ensured increased longterm durability of joint prostheses. However, within 10 years of implantation, about half will show aseptic loosening on plain films. Approximately 1e5% will be affected by infection or septic loosening, about a third of these occurring within 3 months of
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abnormality can be scrutinized for clues as to the underlying aetiology. Septic loosening classically gives rise to initial hyperaemia followed by diffuse uptake around all components of the joint on a dual-phase study, whereas aseptic loosening typically shows little in the way of hyperaemic uptake, and on the delayed phase shows focal uptake at the cut-surface of the bone. However, usually it is not possible to differentiate accurately between the two on bone scan findings alone, which has a maximum overall accuracy of 70% for identifying infection. The next step is to undertake a 99Tc-HMPAO labelled leucocyte or white cell scan. If this is negative in the context of relatively acute symptoms (chronic infection may give a false-negative result due to the lack of neutrophils in the joint), again no further imaging is usually necessary. If the white cell study is positive, however, false-positive results may be obtained due to redistributed marrow, as white cells will marginate to sites of infection as well as bone marrow. Performing a 99Tc-nanocolloid marrow study 5e7 days after the white cell study adds significantly to the accuracy of the latter test. If the distribution of marrow and white cell uptake around the joint is identical (i.e. ‘spatially congruent’), this pattern implies marrow redistribution and aseptic loosening (Figure 20). At sites of infection, there is usually reduced marrow uptake, and a ‘spatially incongruent’ pattern, therefore, implies infection. The strategy of combined or sequential white cell and marrow studies has been shown to have an accuracy of 95% for differentiating infection from aseptic loosening.23
Clinical applications of PET/CT (in orthopaedic practice) Technique Over the last decade, integrated PET/CT has become one of the fastest growth areas in medical imaging, due to the recognition that the combination of metabolic and anatomic information that is provided can have a major impact on patient management.3,4,24 Although many different PET tracers have been developed, the vast majority of PET/CT studies are performed using the non-physiological glucose analogue, 18F-FDG, which exploits in vivo glucose uptake mechanisms and detects the increased glycolytic metabolism exhibited by most cancer cells. FDG PET/CT is now established in the imaging pathways of many different solid-organ tumours, especially non-small cell lung cancer, colorectal tumours, oesophageal malignancy, lymphoma and head and neck cancer. Evidence is also emerging for the routine clinical use of PET/CT in other types of cancer, including hepatobiliary tumours, cervical cancer and melanoma. It has been shown that the increased accuracy of staging, re-staging and therapy response assessment that can be achieved with PET/CT results in significant management changes in 10e40% of cancer patients.3,4 Detailed discussion of the oncological applications of PET/CT is beyond the scope of this article. Patient preparation includes a 4e6 h fast, with an optimal blood glucose level of less than 10 mmol/l. Typically, a patient is injected with 400 MBq FDG, and, after a 60-min uptake period, a scout CT is obtained from the skull base to upper thigh, with subsequent non-contrast-enhanced multidetector CT. The PET acquisition follows immediately, with no change in patient position, and covers the same range, with 2e4 min/bed position. A total of 6e9 overlapping bed positions are usually required.
Figure 20 a Dual-phase bone scan of the knees with anterior views, b anterior and posterior views from a labelled white cell study and c anterior and posterior views from a labelled marrow study. The patient had bilateral knee replacements with pain in the right knee 36 months after surgical implantation. The bone scan a shows diffusely increased blood pool and delayed activity around both aspects of the right prosthesis. As infection needed to be excluded, sequential white cell and marrow scans were performed b and c, which showed identical tracer distribution. This so-called ‘spatial congruence’ indicates marrow redistribution and not infection. The patient underwent single stage revision for aseptic loosening.
implantation.22 The pathological processes underlying both septic and aseptic loosening are remarkably similar, with the main difference being the key presence of neutrophils within the inflammatory joint infiltrate in infected prostheses. However, the management differs significantly, in that the infected replacement requires a more complex two-stage revision, and therefore reliable pre-operative discrimination between septic and aseptic loosening is crucial. The nuclear medicine imaging strategy for a suspected loosened prosthesis usually begins with a dual-phase bone scan. A negative study excludes significant prosthetic complication with a negative predictive value of 95%, and in most cases no further imaging is needed. However, reactive bone uptake after prosthetic surgery may persist for 12 months at the hip and 12e36 months at the knee. Bone scan is, therefore, of limited value in a painful prosthesis within the first 12 months after implantation. Beyond this period, if the bone scan is positive, the pattern of
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Figure 21 FDG PET/CT maximum intensity projection (MIP) and sagittal CT, PET and fused PET/CT images in a patient with metastatic melanoma. There are disseminated liver and bone metastases. Note that many of the vertebral metastases cannot be detected on the CT.
The patient maintains normal tidal respiration throughout the study, which lasts for approximately 30 min. The CT information is used to provide attenuation correction for the PET data and for anatomical co-registration. Standard multimodality workstations enable viewing of fused PET/CT images within minutes of completion of the study. The PET data can be analyzed qualitatively and semi-quantitatively, by measuring the standardized uptake value, which is usually expressed as its maximum (SUVmax). The SUV is defined as the ratio of activity within the tissue (Bq/ml) and decay-corrected total activity injected divided
by body weight (Bq/g). The following sections will discuss in more detail the clinical applications of PET/CT that are relevant to orthopaedic practice. Primary and secondary bone tumours Highly malignant primary bone tumours such as osteosarcoma and Ewing’s sarcoma will invariably show increased FDG uptake. The imaging of these tumours can be performed adequately with conventional techniques such as MR, CT and bone scintigraphy, and there is little evidence to support the
Figure 22 FDG PET/CT maximum intensity projection (MIP) and sagittal CT, PET and fused PET/CT images in a patient with lung cancer (long arrow). The area of abnormal uptake medial to the tumour is shown on the selected sagittal images as corresponding to an upper sternal fracture e the patient had recently undergone cardiopulmonary resuscitation (CPR). There are also a couple of rib fractures (arrowhead ).
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Figure 23 a Bone scan (anterior and posterior views) in a patient with prostate cancer. There are no bone metastases. b. Fluoride-18 PET/CT maximum intensity projection (MIP) and sagittal CT, PET and fused PET/CT images show extremely avid areas of uptake relating to cervical spondylosis, demonstrating the marked increase in sensitivity that can be obtained with this emerging application of PET/CT.
routine use of FDG PET/CT in this setting. Emerging evidence suggests that it may have some use in selected high-risk patients with suspected metastatic or recurrent disease, and in the early assessment of treatment response.25 FDG PET/CT is also limited in its accuracy of differentiating lesser grade malignant tumours from benign lesions, as there can be considerable overlap in the degree of FDG uptake.26
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FDG PET/CT has a higher sensitivity than bone scintigraphy in detecting osseous involvement in some tumour types such as non-small lung cancer, lymphoma and melanoma. When multiple FDG avid bone lesions are detected and/or when there is concordance between the PET and CT findings, FDG PET/CT is extremely accurate at depicting bone metastases, with a positive predictive value of 95% (Figure 21).14 However, it is also
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Figure 24 a FDG PET/CT fused coronal image in a patient with pyrexia of unknown origin (PUO) demonstrates abnormal uptake centred over the T10/T11 disc space. b and c Subsequent MR T1 and T1-gadolinium enhanced sagittal images confirmed T10/T11 discitis and osteomyelitis.
recognized that FDG PET is less reliable at detecting osteoblastic metastases, although the combination of PET and CT can overcome some of this difficulty. This is particularly relevant in tumour types that are associated with mixed-type bone metastases, such as breast cancer, where the sclerotic metastasis may only be seen on the CT component of the study with no appreciable FDG uptake on PET.27 Moreover, FDG uptake is not specific for malignancy, and many benign lesions such as recent fractures, sites of surgical intervention, Paget’s disease, fibrous dysplasia, avascular necrosis, radiation osteonecrosis, osteomyelitis and arthropathy will also show a non-specific increase in FDG accumulation.28 False-positive interpretation of such findings in a patient with cancer should be avoided (Figure 22). Some of these limitations of FDG may be overcome with an alternative PET tracer, 18F-fluoride.29 This is a bone-seeking agent that has an inherently higher bone uptake, considerably faster blood clearance and achieves better target-to-background ratios than the conventional bone scan. Fluoride PET has been shown to have sensitivity of up to 100% for detection of bone metastases, in direct comparative studies with 99Tc-MDP and FDG PET/CT. Specificity is less, and although this can be improved with careful correlation with the morphological findings on the integrated CT component, benign conditions such as active arthropathy can also be extremely avid on fluoride PET and such findings should not be misinterpreted as bone metastases (Figure 23).
when the usefulness of MR may be limited, e.g. in the post-surgical spine, or in the patient with a non-specific presentation, e.g. pyrexia of unknown origin (PUO). The technique shows variable accuracy, with a positive predictive value of 65% but a negative predictive value approaching 100% (Figure 24).30 It may also be useful in the assessment of suspected infection around uncemented metallic prostheses. However, limitations in accuracy can be seen in the context of recent surgical intervention (within 6e12 months), and also with cemented prostheses, as reactive FDG uptake is frequently seen in these scenarios in the absence of infection.
Conclusion Functional imaging techniques in nuclear medicine provide crucial diagnostic information in a variety of clinical settings that are encountered regularly in orthopaedic practice. It is important that the orthopaedic surgeon is aware of the modalities on offer, has a useful working knowledge of how these studies are performed and appreciates the relative strengths and limitations of these techniques. A
REFERENCES 1 Ell PJ, Gambhir SS. Nuclear medicine in clinical diagnosis and treatment. 3rd edn. London: Churchill Livingstone, 2004. 2 Chowdhury FU, Scarsbrook AF. The role of hybrid SPECT-CT in oncology: current and emerging clinical applications. Clin Radiol 2008; 63: 241e51. 3 von Schulthess GK, Steinert HC, Hany TF. Integrated PET/CT: current applications and future directions. Radiology 2006; 238: 405e22. 4 Blodgett TM, Meltzer CC, Townsend DW. PET/CT: form and function. Radiology 2007; 242: 360e85. 5 Saha G. Fundamentals of nuclear pharmacy. 4th edn. Berlin: Springer-Verlag, 1998.
Infection imaging FDG uptake is not specific for malignancy as enhanced glycolytic metabolism is also exhibited by activated macrophages, monocytes and neutrophils, which are all involved in the recruitment, activation and healing phases of tissue inflammation. FDG PET/CT has been shown to have a role in imaging of suspected spinal infection
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6 Cherry S, Sorenson J, Phelps M. Physics in nuclear medicine. Amsterdam: Elsevier, 2003. 7 Patton J, Sandler M, Berman D, et al. D-SPECT: a new solid state camera for high speed molecular imaging. J Nucl Med 2006; 47: 189. 8 Keidar Z, Kagna O, Frenkel A, Israel O. A novel ultrafast cardiac scanner for myocardial perfusion imaging (MPI): comparison with a standard dual-head camera. J Nucl Med 2009; 50: 478. 9 Bailey D, Townsend D, Valk P, Maisey M. Positron emission tomography. London: Springer-Verlag, 2005. 10 Mettler FA, Guiberteau MJ. Essentials of nuclear medicine imaging. 5th edn. Philadelphia: Saunders Elsevier, 2006. 11 Administration of Radioactive Substances Advisory Committee (ARSAC). Notes for guidance on the clinical administration of radiopharmaceuticals and use of sealed radioactive sources. London: Health Protection Agency, 2006 (revised 2007). 12 Zuckier LS, Freeman LM. Nonosseous, nonurologic uptake on bone scintigraphy: atlas and analysis. Sem Nucl Med 2010; 40: 242e56. 13 Oberlin O, Bayle C, Hartmann O, Terrier-Lacombe MJ, Lemerle J. Incidence of bone marrow involvement in Ewing’s sarcoma: value of extensive investigation of the bone marrow. Pediatr Blood Cancer 1995; 24: 343e6. 14 Even-Sapir E. Imaging of malignant bone involvement by morphologic, scintigraphic, and hybrid modalities. J Nucl Med 2005; 46: 1356e67. 15 Coleman RE, Mashiter G, Whitaker KB, et al. Bone scan flare predicts successful systemic therapy for bone metastases. J Nucl Med 1988; 29: 1354e9. 16 Sohaib SA, Cook G, Allen SD, et al. Comparison of whole-body MRI and bone scintigraphy in the detection of bone metastases in renal cancer. British J Radiol 2009; 82: 632e9. 17 Holder LE, Schwarz C, Wernicke PG, Michael RH. Radionuclide bone imaging in the early detection of fractures of the proximal femur (hip): multifactorial analysis. Radiology 1990; 174: 509e15.
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18 Love C, Din AS, Tomas MB, Kalapparambath TP, Palestro CJ. Radionuclide bone imaging: an illustrative review. Radiographics 2003; 23: 341e58. 19 Imhof H, Breitenseher M, Trattnig S, et al. Imaging of avascular necrosis of bone. Eur Radiol 1997; 7: 180e6. 20 Duman I, Dincer U, Taskaynatan MA, et al. Reflex sympathetic dystrophy: a retrospective epidemiological study of 168 patients. Clin Rheumatol 2007; 26: 1433e7. 21 Palestro CJ, Love C, Bhargava KK. Labeled leukocyte imaging: current status and future directions. Q J Nucl Med Mol Imaging 2009; 53: 105e23. 22 Palestro CJ. Nuclear medicine, the painful prosthetic joint, and orthopedic infection. J Nucl Med 2003; 44: 927e9. 23 Love C, Tomas MB, Marwin SE, et al. Role of nuclear medicine in diagnosis of the infected joint replacement. Radiographics 2001; 21: 1229e38. 24 Blodgett TM. PET/CT with correlative diagnostic CT. Salt Lake City: Utah: Amirsys, 2009. 25 Lakkaraju A, Patel CN, Bradley KM, Scarsbrook AF. PET/CT in primary musculoskeletal tumours: a step forward. Eur Radiol 2010; 20: 2959e72. 26 Aoki J, Watanabe H, Shinozaki T, et al. FDG PET of primary benign and malignant bone tumours: standardized uptake value in 52 lesions. Radiology 2001; 219: 774e7. 27 Cook GJ. PET and PET/CT imaging of skeletal metastases. Canc Imag 2010; 10: 1e8. 28 Liu Y, Ghesani NV, Zuckier LS. Physiology and pathophysiology of incidental findings detected on FDG-PET scintigraphy. Semin Nucl Med 2010; 40: 294e315. 29 Grant FD, Fahey FH, Packard AB, et al. Skeletal PET with 18F-Fluoride: applying new technology to an old tracer. J Nucl Med 2008; 49: 68e78. 30 Love C, Tomas MB, Tronco GG, Palestro CJ. FDG PET of infection and inflammation. Radiographics 2005; 25: 1357e68.
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(iv) Imaging of non-accidental injury
Learning points C
Jeannette K Kraft
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Abstract C
Child abuse (including physical injury, emotional abuse, sexual abuse and neglect) is a social problem that is increasingly recognized not only by health care professionals but also by the government and public. Nonaccidental injury (NAI) is defined as injury of a child resulting from an abusive act by a carer. All clinicians treating children including orthopaedic surgeons should be able to recognize common presentations of NAI, identify typical fractures resulting from abuse and initiate child protection investigations to prevent further injury to the child. This article focuses on non-accidental skeletal injury. It explains the importance of a detailed skeletal survey that should be performed to agreed standards by trained radiographers and reported by a radiologist with experience in paediatric trauma imaging. Typical fractures are illustrated and important differential diagnoses are discussed.
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All doctors have a legal duty to initiate child protection proceedings if they suspect NAI. Discrepancy between the presented history and imaging findings should alert the clinician. Children under 2 years with suspected NAI should be investigated with a skeletal survey. High quality imaging undertaken according to set guidelines is essential. Multiple fractures are more common in abuse than accidental trauma. Rib fractures and metaphyseal fractures are highly specific for NAI. Long bone fractures from abuse are more commonly seen in the pre-mobile child. Protecting the child from further injury is paramount.
final diagnosis of NAI is usually reached after considering the radiological findings in the light of the history provided and assessing findings from the physical examination.
Keywords child abuse; imaging; non-accidental injury; radiography
Recognizing non-accidental injury NAI should be suspected if the history given by the carer does not match the suspected mode of injury for the presented fracture, if the history changes between carers or on repeated telling or if no plausible history for the injury can be provided. Most cases of NAI occur in the pre-mobile child. It is important to assess that the injury is in keeping with the motor development of the child. For instance, a 6-week-old baby will not be physically able to roll over before falling off a changing table. The clinician treating this child should recognize this discrepancy and initiate further investigations. Injuries should be treated as suspicious if there is no witness or if siblings are blamed. If a delay in seeking medical attention without credible explanation or previous concerns regarding the child or siblings are noted the child should be assessed carefully. NAI must be considered if the timing of the injury given in the history differs from the timing derived from investigations e.g. history of an acute injury but prominent callus formation on radiographs. Sometimes NAI is suspected indirectly when the radiologist recognizes a typical fracture associated with child abuse e. g. rib fractures on a radiograph taken for suspected chest infection. Multiple fractures are more common in abuse than in accidental trauma.6,7 Multiple fractures in different stages of healing and certain fractures such as rib and metaphyseal fractures have a strong association with NAI and warrant careful assessment of the child. Unusual fractures should also alert the orthopaedic surgeon (Figure 1).
Introduction and epidemiology Non-accidental injury (NAI) is defined as injury resulting from an abusive act by a parent or carer perpetrated on a child. It may or may not be intentional but an independent witness would usually recognize if the child was treated inappropriately. NAI is the term given to define physical abuse. However other forms of child abuse namely emotional abuse, sexual abuse and neglect may occur simultaneously. The main focus of this article is on skeletal injury caused by NAI. Head injury and neuroimaging is not discussed in detail but the reader can find further information on this topic in recently published articles.1e3 Health care professionals but also the public and the government have become increasingly aware of NAI. In Britain the number of children being referred to social services (547,000 in 2009 compared to 538,500 in 2008) and also the number of children becoming the subject of a child protection plan (37,900 in 2009 compared to 34,000 in 2008) are increasing.4 However this increasing demand and the public’s desire to see improvements in the safeguarding of children have put a strain on the health care system and social services.5 The role of the clinician looking after children encompasses detection of abuse and medical management of the injured child but also appropriate referral and prevention of further abuse. Imaging plays an important role in the evaluation of trauma. The
Clinical assessment and history taking in suspected NAI Fractures due to abuse present only a small number of childhood fractures. Most children sustain fractures from accidental causes such as household and playground falls or road traffic accidents.6 If a child presents with a suspicious injury a careful clinical history should be taken from the carer. The interviewer should
Jeannette K Kraft MD MRCP FRCR Consultant Paediatric Radiologist, Clarendon Wing Radiology Department, Leeds General Infirmary, Leeds, LS1 3EX, United Kingdom. Conflicts of interest: none.
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Case study: A 5months old boy presented to the Accident and Emergency department with injury to his right arm. a Lateral radiograph of the elbow demonstrated a supracondylar fracture. The history given for this injury was inconsistent and a supracondylar fracture in a non-mobile child is unusual (arrow). This prompted a skeletal survey which showed rib fractures (white arrows) and a metaphyseal fracture (black arrow) of the left proximal humerus b. Both fracture types are regarded as highly specific for child abuse. An old fracture of the right tibia with prominent periosteal reaction was also diagnosed (arrows). c No credible explanation for these injuries was provided. Fractures of different ages such as the acute fracture of the elbow and the healed fracture of the tibia are very suspicious of child abuse. Figure 1
seek detailed information regarding the exact time and mode of injury. Questions should include the height the child fell from, the surface it fell on (e.g. carpeted floor or concrete) and if there were witnesses present. Older children should be interviewed, if possible without the carer present. There may however be occasions when a child might not tell the truth about how an injury was sustained. Especially in unexplained and multiple injuries the clinician taking the history should also seek information regarding a possible underlying bone disease such as metabolic bone disease of prematurity or osteogenesis imperfecta. Questions regarding the child’s gestational age, age at first injury and a family history of frequent injuries with minor trauma, late walking or early onset of osteoporosis can provide clues regarding an underlying bone disease.8 An experienced paediatrician will be able to give further guidance. A full clinical examination should seek sites of soft tissue swelling, bruising or pain. It has however been noted that bruising is absent in over half of children with inflicted fractures and when present it may be well away from the site of injury.9 An ophthalmological examination will evaluate possible retinal haemorrhage. Detailed documentation is paramount especially for court proceedings that may follow.
The Royal College of Radiologists and The Royal College of Paediatrics and Child Health in the UK and by the American College of Radiology.10,11 A full skeletal survey comprises high quality radiographs of the entire skeleton which includes separate views of all four limbs, the chest, spine, skull, abdomen, pelvis, hands and feet (Table 1). The Royal College of Paediatrics
The Royal College of Radiology and Royal College of Paediatrics and Child Health standard child protection skeletal survey for suspected NAI11 Skull Anterior posterior (AP), lateral and Townes view Chest AP view including clavicles Oblique views of both of the sides of the chest to show ribs Abdomen AP view of the abdomen including pelvis and hips Spine Lateral view of the cervical, thoracic and thoraco-lumbar regions AP projections of the spine are included on the AP projection of the chest and abdomen Limbs AP view of both arms AP view of both forearms AP view of both femurs AP view of both legs Postero-anterior view of both hands Dorso-palmar view of both feet
Investigating suspected NAI Skeletal survey A skeletal survey is the standard initial imaging method for the assessment of children with suspected NAI.10 It is performed to detect occult fractures and exclude underlying bone dysplasia or metabolic condition and to aid dating of fractures. The reasons to perform a skeletal survey have to be detailed in the patient’s notes. A skeletal survey should be performed according to agreed standards. Standards have been published in a joint document by
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Table 1
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and Child Health in the UK and the American College of Radiology standards differ mainly in the assessment of the chest. The American document suggests chest imaging with a two view protocol (anterioreposterior and lateral projection of the chest) while the British document favours a three view protocol (anterioreposterior and two oblique views of the ribs). All images should be taken by radiographers experienced in paediatric imaging. A single total body radiograph (babygram) must not be performed. The imaging should be supervised by an experienced radiologist who will also advise on additional views. Initially a single view of each bone is obtained. A suspicious area is further evaluated with additional coned views and radiographs in orthogonal planes. Equally if clinical signs such as bruising or swelling indicate an injury, 2 orthogonal views of the area are obtained. This is standard radiographic practice for all cases of trauma. Metaphyseal fractures may only be visualized on one of several views obtained. Three views of the chest are performed consisting of a conventional frontal radiograph and oblique views of the ribs. This has been shown to increase the sensitivity and specificity of the skeletal survey in detecting rib fractures with increased diagnostic accuracy by about 9%.12
involve a radiation dose of approximately ten months of background radiation. However a CT scan of the abdomen involves a much higher radiation dose of approximately 4e5 years of background radiation. Risk estimation associated with diagnostic imaging is complex as different organs exhibit different sensitivities to radiation. Children are generally more sensitive to radiation than adults.10 Reporting skeletal surveys All skeletal surveys should be reported by radiologists experienced in reporting paediatric trauma imaging. Double reporting of skeletal surveys ensures that no fractures are missed or overcalled. Other imaging modalities Nuclear medicine studies: bone scintigraphy can be used to complement the skeletal survey. Bone scintigraphy has a higher sensitivity than the skeletal survey for rib fractures but a lower sensitivity for the metaphyseal fracture and skull fracture. Kemp et al. concluded that neither modality alone detected all fractures.13 Bone scanning can become positive within 7 h of an injury and remain positive for up to 1 year.13 Bone scintigraphy may be the preferred option if a follow up skeletal survey in 11e14 days cannot be performed either due to problems regarding safeguarding of the child during this interval or concerns about failure to attend any follow up imaging. Any positive sites on bone scanning will require confirmatory radiographs. The specificity of bone scintigraphy is lower than radiographs as bone scans can also be positive in infection or malignancy.
Who should be imaged? Every child under the age of 2 where physical abuse is suspected should have a full skeletal survey. Older children can often give a history and indicate the site of pain which is then further evaluated with radiographs. This should be assessed on an individual basis after discussing with health care professionals involved. When one child in a family presents with suspected NAI siblings are also assessed. Kemp et al. could not find sufficient detail to support performing skeletal surveys in siblings of abused children.13 However siblings under the age of two living in the same environment are often investigated with a skeletal survey. In older children individual assessment is usually made and areas of concern such as bruised or painful limbs/joints are imaged with a standard 2 view radiographic series.
Cross sectional imaging: as in accidental trauma CT is used to define the extent and severity of complex fractures especially within the bony pelvis, the spine and complex fractures involving joints. If injuries of the thorax and abdomen are suspected they will be investigated as for accidental trauma with contrast enhanced CT or ultrasound. CT is the investigation of choice for suspected head injury. It is highly sensitive and specific for the detection of intracranial haemorrhage and secondary changes such as cerebral oedema and infarction. Magnetic Resonance Imaging (MRI) has superior ability to define parenchymal injury and the detection of subacute and chronic haemorrhage.
Obtaining consent Good communication is important if the child is to be safely investigated. The clinician looking after the child, usually a paediatrician, has to carefully and accurately convey the concern to the family/carer, explain the imaging procedures planned and the risk/benefit involved. This should be documented in the patient’s notes.
Follow up imaging
Radiation dose In the UK each examination using ionizing radiation such as a skeletal survey, bone scintigraphy and computed tomography has to be justified according to the Ionizing Radiation (Medical Exposure) Regulations 2000 IR(ME)R.14 The clinician has to provide sufficient clinical information to the radiographer and radiologist to allow for this process. Plain radiography involves a relatively low radiation dose when compared to background radiation. A chest radiograph for example carries a radiation dose comparable to 3 days of background radiation. A skeletal survey involving multiple radiographs is comparable to four to eight months of background radiation. A computed tomography (CT) scan of the head may
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Once a fracture shows signs of healing it is more easily visualized on radiographs. Studies have shown that the detection rate of rib and metaphyseal fractures increased by 27% (although those studies did not use oblique views of the ribs in the original skeletal survey).15 Therefore follow up radiographs of suspicious areas can confirm a fracture and help with dating it. In other cases follow up imaging might contribute to the exclusion of the diagnosis. Timing of follow up radiographs is important and usually recommended 11e14 days after the initial skeletal survey.10 A repeat full skeletal survey may highlight further occult fractures and is sometimes necessary in cases of ongoing
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rib head and neck.17 A blunt direct impact can also cause rib fractures. External signs may be absent and therefore chest radiography is necessary to confirm rib fractures. According to a systematic review by Maguire et al. rib fractures in children rarely occur in cardiopulmonary resuscitation (CPR) when performed on a hard surface by trained medical practitioners or lay people.18 If rib fractures occur during resuscitation they are likely to be anterior and multiple. Posterior rib fractures after resuscitation have not been reported. If the child is laid on a hard surface no sufficient leverage force on the transverse process can be generated during CPR to generate a fracture.17 Acute rib fractures appear as linear lucent lines across the rib. Early after injury the fractures may be difficult to detect due to overlying lung markings, because the fracture is not displaced or due to the orientation of the X-ray beam relative to the fracture. Oblique views of the ribs are especially helpful and increase the detection rate of rib fractures by 9%.12 They are part of a skeletal survey performed according to ‘Standards for radiological investigation of suspected Non-accidental injury’ in the UK.10 Rib fractures become more obvious during healing which is the reason for repeat chest radiographs 2 weeks after an initial skeletal survey. During healing faint sclerosis of the rib, subtle periosteal reaction, callus formation or widening of the neck of the rib makes injury more conspicuous. Sometimes a small pleural effusion or some pleural thickening may be evident (Figure 2).
concern. A follow-up chest radiograph after 2 weeks to identify healing rib fractures through callus formation is usually performed as a minimum follow up.10 There are potential problems with a policy of follow up imaging. This includes the possible delay in reaching a final diagnosis, problems with managing the family and child, safeguarding the child and siblings in the interim and non-attendance for follow up imaging studies. Robust mechanisms have to be in place to ensure the dedicated doctor or nurse is informed in case of non-attendance.
Radiological findings in NAI Fractures are a common childhood problem with one-third of girls and boys sustaining at least one fracture before the age of 17 years mostly from falls, motor vehicle accidents and other accidental trauma.16 Most NAI occurs in children under 3 years of age and 80% of such fractures occur in children younger than 18 months.6,7 In contrast 85% of accidentally caused fractures occur in children over the age of 5 years.6 Therefore the likelihood of a fracture being caused non-accidentally increases with decreasing age. Almost any type and location of fracture has been reported in abused children. However some fractures are regarded as more specific for NAI (Table 2). Rib fractures Accidental rib fractures are uncommon in children even in major trauma. A young child’s ribs are soft and tend to bend and deform with trauma rather than fracture as typically seen in adults. According to a meta-analysis by Kemp et al a child with rib fractures has a 7 in 10 chance of having been abused.6 Rib fractures from abuse can be found in any location along the rib. They tend to be bilateral and are commonly reported in the posterior or axillary portion of the rib. Children who have rib fractures from abuse have more fractures than those who had not been abused.6 A flail chest can occur if a row of fractures involves the posterior and lateral parts of the chest. Anterior rib fractures can be associated with abdominal trauma. Rib fractures may be caused by anterior-posterior compression of the chest which is a very specific mechanism seen in child abuse. The perpetrator holds the infant by the chest with the palms at the sides and the fingers at the back causing a forceful squeezing motion. Often the child is also vigorously shaken. The posterior rib is attached relatively tightly to the vertebral body. Excessive leverage of the posterior part of the rib over the vertebral transverse process as a fulcrum leads to fractures of the
Metaphyseal factures Caffey first described the metaphyseal fracture in child abuse and introduced the terms corner and bucket handle fracture.19 These fractures are regarded as highly specific for child abuse. They most often occur in the distal femur, proximal and distal tibia and proximal humerus.20,21 The mechanism of injury involves shearing and rotational forces which occurs with violent shaking
Fractures commonly seen in NAI that warrant further imvestigation C C C C C C C
Metaphyseal fractures Rib fractures Multiple fractures Fractures at different stages of healing Skull fractures especially if complex Occult fractures Long bone fractures in the pre-mobile child
Figure 2 12 week old child presenting with numerous bilateral healing rib fractures. Note the pleural thickening along the right chest wall which can be seen with fractures.
Table 2
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fracture is inconspicuous but the peripheral thicker portion is viewed directly as a triangular shaped bone fragment called a corner fracture (Figure 3). In three-dimensions there are no corners but a continuous rounded or ovoid contour with a dense thicker periphery of the disk-like fragment.20 Repeated assault can result in metaphyseal fraying. Like most other fractures metaphyseal fractures can produce periosteal reaction and callus formation during healing if the periosteum is disrupted. Typically however metaphyseal fractures heal by bone absorption without callus formation or periosteal reaction. Healing therefore leads to a gradual, almost imperceptible healing across the metaphyseal margin. This can cause problems with accurately dating such fractures but serial follow up radiographs may assist. Many metaphyseal fractures become inconspicuous at 4 weeks and are healed at 6weeks.23
as the infant is held by the trunk or extremities. Therefore metaphyseal fractures are almost always seen in small children under the age of 2 years as they are unable to protect their extremities. Bruising overlying metaphyseal fractures is often absent.9 The metaphysis is the part of the bone between the diaphysis or shaft of the bone and the growth plate. The metaphyseal fracture seen in NAI is a transmetaphyseal disruption of the trabeculi of the primary spongiosa of the growing bone. This results in a disk like fragment of bone and calcified cartilage. Centrally the fracture abuts the chondro-osseous junction. Peripherally it turns away from the physis and undercuts a larger peripheral fracture fragment because more trabeculi and the subperiosteal bone collar are located there.22 The radiographic projection and position influence the appearance of the fracture line on radiographs resulting in the characteristic patterns typically described with metaphyseal fractures. If angled slightly caudally or cranially a crescent shaped fragment is visible often termed a bucket handle fracture.22 If viewed at right angles the central, slightly oblique portion of the
Long bone fractures Long bone fractures seen in the paediatric emergency department are a common finding in ambulatory children. The younger the
2 week old baby presenting with leg injury. AP a and lateral b radiographs of the left leg show metaphyseal fractures of the proximal and distal tibia and fibula (arrows). Note that the metaphyseal injury appears as a corner fracture in one projection and as a bucket handle type fracture in the corresponding projection. Figure 3
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Once the child is able to walk or pull up from standing a femoral fracture can be sustained from a fall with a twisting motion. A fine spiral fracture of the tibia (often named a toddlers’ fracture) is a well known accidental fracture in the mobile child. According to Kemp et al. a child under 3 years of age with a humeral fracture has a one in two change of having been abused.6 Midshaft spiral fractures of the humerus are more likely due to abuse whereas supracondylar fractures are more likely due to accidental trauma.6,25 Skull fractures In children under 3 years skull fractures are the most common fracture type in abused and non-abused children.6 There is no specific pattern of skull fracture differentiating abuse from accidental trauma. Therefore it is not possible to assess the radiological features of a skull fracture to identify if it was caused accidentally or through non-accidental trauma.2 The most common fracture in both accidental and abusive trauma is a linear fracture and the most common location is parietal (Figure 5). Multiple, diastatic and bilateral fractures and fractures that cross a suture are significantly more common in abused children.6,26 Skull radiographs should be performed even if a CT scan has been obtained or is planned as it has been shown that skull fractures can be missed by CT.10 A skull fracture results from direct impact trauma to the head. Minor falls are very rarely associated with severe or fatal head injury. However significant intracranial injury can be seen without a skull fracture when shaking occurs as the mechanism of injury. Therefore any child who presents with signs of physical abuse and neurological symptoms and any child with suspected NAI under the age of 1 year should be investigated with a cranial CT scan.10 After significant head injury a scalp haematoma is often visible. Most haematomas disappear after 3e4 days and the presence of a haematoma suggests a recent fracture. Skull fractures do not heal with callus formation
Figure 4 4 week old baby presenting with a femoral fracture with inconsistent history.
child the more likely it is the fracture was caused by non-accidental trauma. This is related to the developmental ability of the child. For a non-walking child who is unable to pull to a standing position it is difficult to sustain a long bone fracture from a simple accident. Diaphyseal or shaft fractures are more likely due to abuse when multiple or seen in a state of healing suggesting a delay in seeking medical attention. According to a systematic review by Kemp et al. a child with a femoral fracture has a 1 in 3e4 chance of having been abused.6 A midshaft fracture is the most common site of a femoral fracture in accidental and non-accidental trauma. In children who are not yet walking spiral femoral fractures are more commonly seen from abuse.6,24 A spiral fracture will require a rotational force. It could be sustained when the child is inappropriately pulled by the limb or falls awkwardly when thrown. The mechanism of injury for a transverse fracture is usually an indirect bending force or direct blow to the bone (Figure 4).
3 month old girl with cranial injury. a Lateral skull radiograph demonstrates a complex parietal skull fracture (black arrows) with overlying soft tissue swelling (white arrows), b CT image on bone windows demonstrating right sided fracture (short arrow) with overlying soft tissue swelling (long arrows). Brain imaging also demonstrates a subdural haematoma (not shown). Figure 5
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Figure 6 10 week old child presenting with apnoea and bleeding from the mouth following strangulation. A pelvic radiograph shows bilateral pubic rami fractures (arrows). In addition the skeletal survey also highlighted rib fractures and metaphyseal fractures to the humerus and tibia (not shown).
Figure 7 5 months old boy presenting collapsed and in poor condition. A chest radiograph demonstrates free intraperitoneal gas due to bowel perforation (long arrows) and multiple healing rib fractures (short arrows).
which makes dating difficult. If the edges of the fracture are smooth and less distinct the fracture is more than 2 weeks old.
fractures but there is little evidence in the literature to validate them.28 Posser et al. recently reviewed the literature to define the evidence for radiologic dating of fractures and concluded that periosteal reaction can be seen as early as 4 days after injury and is present in at least 50% of cases by 2 weeks.27 Early callus is first noted at 7 days after injury and is seen in 50% of cases at 4 weeks, hard callus peaks at about 8 weeks after injury. Remodelling is seen from 3 months to up to a year after injury. Therefore it is easier to evaluate a recent fracture which can be dated more accurately than a healing fracture. It has been suggested that fractures heal at different rates with younger children showing faster bone healing. This has not been scientifically proven. However skull and metaphyseal fractures do not typically heal with callus formation and are therefore more difficult to date. Bone scans are not helpful in dating fractures as they show positive results as early as 7 h after a fracture and can show positive results for as long as 1 year.27
Other fractures Virtually any fracture type and location has been described in the setting of NAI. Especially fractures in atypical sites (acromion, sternum, pubic rami, phalanges in very young children) should be treated suspicious for NAI as they rarely occur in accidental trauma. Compression fractures of the vertebrae and fracture dislocation of vertebral bodies as well as pelvic fractures have been reported in NAI (Figure 6). Visceral and soft tissue injury Violent beating may result in haematomas that can eventually calcify and might be visible radiologically. Abdominal trauma can lead to bowel perforation and pancreatic injury (Figure 7).
Dating fractures In the court setting radiologists are often asked to date fractures. During healing fractures go through a recognized sequence of histopathological changes. These correspond to radiographic features that are demonstrated on X-rays. Initially subperiosteal new bone formation is seen followed by loss of fracture line definition, soft callus and hard callus formation and finally bone remodelling. The radiologic features of bone healing show a continuum with considerable overlap.27 Paediatric radiologists use their clinical experience gained by reviewing radiographs obtained after accidental trauma to evaluate the stage of healing of a fracture. This helps with dating the time of injury. Charts derived from experience of the authors of textbooks have been used to help evaluate the healing stage of
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Differential diagnosis Most often, especially when the injury is isolated, the differential diagnosis is between an atypical presentation of accidental trauma and NAI. In a young child late presenting birth trauma needs to be considered. Skull fractures may occur after instrumental delivery e.g. forceps delivery. Clavicular fractures can be seen with shoulder dystocia and femoral fractures after breech extraction which may not be immediately evident. Birth injury may even cause metaphyseal fractures especially after caesarean section. A detailed birth history should be taken.
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Figure 9 Newborn child with limb deformities. A chest radiograph performed on day one of life shows numerous rib fractures in different stages of healing, clavicular fractures with callus formation as well as a healing and an acute humeral fracture. The child was diagnosed with osteogenesis imperfecta.
such as blue sclera or radiological features including osteopenia (Figure 9). If there is clinical doubt genetic analysis can be performed but this is currently confined to specialist centres. Consultation with an endocrinologist or geneticist may be required if mild forms of osteogenesis imperfect or metabolic conditions need to be excluded. Metaphyseal chondrodysplasia type Schmidt and spondylometaphyseal dysplasia, corner fracture type can show metaphyseal fragments that might mimic fractures on a skeletal survey. However a follow up skeletal survey will show no change in the appearances and no signs of healing. Rarely fractures are iatrogenic. Children with neuromuscular disorders receiving vigorous physiotherapy have been reported to sustain fractures. Grayev et al. described metaphyseal fractures in children undergoing serial casting for club foot correction.29 Occasionally developmental variants can be difficult to differentiate from fractures. The normal step off of the metaphyseal collar as it approaches the physis, metaphyseal spurs especially around the knee and wrist and metaphyseal fragmentation of the distal femur or proximal tibia associated with
4 week old premature baby (25 weeks gestation). a Radiograph of the left arm shows a mid-shaft fracture of the humerus (long arrow) and a proximal metaphyseal humeral fracture (short arrow). b Radiograph of the left leg shows healing metaphyseal fractures of the proximal and distal femur as well as the distal tibia (arrows). Similar fractures were seen in the right leg (not shown). The bones are very osteopenic in keeping with metabolic bone disease of prematurity. He had not been discharged from the neonatal unit. Figure 8
Differential diagnosis of nonaccidental fractures Taking a careful clinical and family history may highlight fracturing associated with minor injury therefore suggesting an underlying bone disease. If a child is born severely premature prolonged ventilation and parental nutrition may lead to metabolic bone disease of prematurity and increased risk of fracturing (Figure 8). In rickets metaphyseal irregularities and fragmentation may be seen in addition to the characteristic physeal widening and osteopenia. However laboratory findings typical of rickets will be able to differentiate.8 An underlying bone dysplasia causing excessive fracturing is usually diagnosed on clinical and radiological grounds. Osteogenesis imperfecta may be suggested by clinical features
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C
C
C C
C C
Birth injury e.g. clavicular fracture with shoulder dystocia, skull fracture with instrumental delivery Metabolic bone disease e.g. Rickets, Osteopenia of prematurity, Cooper deficiency Sepsis e.g. osteomyelitis Bone dysplasia, e.g. osteogenesis imperfecta, metaphyseal chondrodysplasia Malignancy, neuroblastoma, leukaemia Insensitivity to pain
Table 3
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physiological bowing may cause difficulties.30 A follow up skeletal survey will show no change in the appearances and may sometimes be required. Physiological periosteal reaction can also cause confusion in interpreting the findings of a skeletal survey. If benign it is usually thin, bilateral and symmetrical more often affecting the femora, humeri or tibiae. Malignancies such as leukaemia or neuroblastoma and osteomyelitis might show radiographic findings that could mimic NAI (Table 3).
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Multidisciplinary team approach and medico-legal issues 9
Children with suspected NAI might present to different health care professionals including the general practitioner, emergency department staff, a paediatrician or orthopaedic surgeon in a fracture clinic. Early involvement of the paediatric team should be sought especially if the paediatric experience of the assessing doctor is limited. A close working relationship with the radiology department and clear communication between all health care professionals are essential if the child is to be adequately investigated. In the UK, if NAI is suspected the child will be referred to social services and civil court proceedings start. While the child is moved to a safe place, social services, the police and the court will try to act in the child’s best interest. Medical health care professionals may be asked to provide reports in relation to suspected NAI. In legal proceedings a factual report or expert opinion may be required. The expert opinion should be straightforward, not misleading or biased and well researched. A report may be commissioned by one of the parties and the health care professional providing it should remember to be a witness to the court and not an advocate for either side.10
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Research directions High quality published studies in the field of child abuse are limited. Further research should focus on pre-school children and include larger populations focussing on the presentation and outcome of each individual case. Future studies also need to include disabled children who appear underrepresented in the literature but are at high risk. A
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18 REFERENCES 1 Fernando S, Obaldo RE, Walsh IR, Lowe LH. Neuroimaging of nonaccidental head trauma: pitfalls and controversies. Pediatr Radiol 2008; 38: 827e38. 2 Stoodley N. Neuroimaging in non-accidental head injury: if, when, why and how. Clin Radiol 2005; 60: 20e30. 3 Kemp AM, Rajaram S, Mann M, et al. What neuroimaging should be performed in children in whom inflicted brain injury in suspected? A systematic review. Clin Radiol 2009; 64: 473e83. 4 Referrals, assessment and children and young people who are the subject of a child protection plan, England - Year ending 31 March 2009, Department of Children, Schools and Families, 17 September 2009 (available online at http://www.dcsf.gov.uk/rsgateway/DB/SFR/ s000873/index.shtml). Accessed September 2010. 5 The chief adviser on the safety of children, First annual report to the parliament - 2010, Sir Roger Singleton March 2010 (available online
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at http://publications.education.gov.uk/default.aspx?PageFunction¼ productdetails&PageMode¼publications&ProductId¼DCSF-0031002010). Accessed September 2010. Kemp AM, Dunstan F, Harrison S, et al. Pattern of skeletal fractures in child abuse: A systematic review. BMJ 2008; 337: 1518e26. Worlock P, Stower M, Barbor P. Patterns of fractures in accidental and on-accidental injury in children: a comparative study. BMJ 1986; 293: 100e2. Bishop N, Sprigg A, Dalton A. Unexplained fractures in infancy: looking for fragile bones. Arch Dis Chil 2007; 92: 251e6. Peters ML, Starling SP, Barnes-Eley ML, Heisler KW. The presence of bruising associated with fractures. Arch Pediatr Adolesc Med 2008; 162: 877e81. The Royal College of Radiologists and Royal College of Paediatrics and Child Health. Standards for radiological investigations of suspected non-accidental injury. London: RCR/RCPCH, 2008. American College of Radiology. ACR practice guideline for skeletal surveys in children. 2006 (available online at http://www.acr.org/ secondarymainmenucategories/quality_safety/guidelines/pediatric/ skeletal_surveys.aspx). Accessed October 2010. Ingram JD, Connell J, Hay TC, Strain JD, Mackenzie T. Oblique radiographs of the chest in nonaccidental trauma. Emerg Radiol 2000; 7: 42e6. Kemp AM, Butler A, Morris S, et al. Which radiological investigations should be performed to identify fractures in suspected child abuse? Clin Radiol 2006; 61: 723e36. Health and Safety Legislation. Statutory Instrument 2000 No.1059 The Ionising Radiation (Medical Exposure) Regulations 2000 (available online at http://legislation.hmso.gov.uk/si/si20001059.htm). Accessed online September 2010. Kleinman PK, Nimkin K, Spevak MR, et al. Follow up skeletal surveys in suspected child abuse. Am J Roentgenol 1996; 167: 893e6. Cooper C, Dennison EM, Leufkens HGM, Bishop N, vanStaa TP. Epidemiology of childhood fractures in Britain: A study using the general practice research database. J Bone Miner Res 2004; 19: 1976e81. Kleinman PK, Schlesinger AE. Mechanical factors associated with posterior rib fractures: laboratory and case studies. Pediatr Radiol 1997; 27: 87e91. Maguire S, Mann M, John N, et al. Does cardiopulmonary resuscitation cause rib fractures in children? A systematic review. Child Abuse Negl 2006; 30: 739e51. Caffey J. Multiple fractures in the long bones of infants suffering from chronic subdural haematoma. AJR 1946; 56: 163e73. Kleinman PK, Marks SC, Blackbourne B. The metaphyseal lesion in abused infants: A radiologic-histophathologic study. AJR 1986; 146: 895e905. Kleinman PK, Marks SC. A regional approach to the classic metaphyseal lesion in abused infants: The distal femur. AJR 1998; 170: 43e7. Kleinman PK, Marks SC. Relationship of the subperiosteal bone collar to metaphyseal lesions in abused infants. J Bone Joint Surg Am 1995; 77: 1471e6. Kleinman PK. Problems in the diagnosis of metaphyseal fractures. Pediatr Raiol 2008; 38(Suppl 3): S388e94. Beals RK, Tufts E. Fractured femur in infancy: The role of child abuse. J Pediatr Ortho 1983; 3: 583e6.
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25 Strait RT, Siegel RM, Shapiro RA. Humeral fractures without obvious etiologies in children less than 3 years of age: When is it abuse? Pediatrics 1995; 96: 667e71. 26 Hobbs CJ. Skull fracture and the diagnosis of abuse. Arch Dis Child 1984; 59: 246e52. 27 Prosser I, Maguire S, Harrison SK, et al. How old is this fracture? Radiologic dating of fractures in children: A systematic review. Am J Roentgenol 2005; 184: 1282e6. 28 O’Conner J, Cohen J. Dating fractures. In: Kleinman PK, ed. Diagnostic Imaging of child abuse. 2nd edn. St Louis. MO: Mosby, 1998: 168e77.
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29 Grayev AM, Boal DKB, Wallach DM, Segal LS. Metaphyseal fractures mimicking abuse during treatment for clubfoot. Pediatr Radiol 2001; 31: 559e63. 30 Kleinman PK, Belanger PL, Karellas A, Spevak MR. Normal metaphyseal radiological variants not to be confused with findings of infant abuse. AJR 1991; 156: 781e3. FURTHER READING Kleinman PK, ed. Diagnostic Imaging of child abuse. 2nd edn. St. Louis: Mosby, 1998.
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(v) The basic science of MRI
tend to align with or against the magnetic field and precess around it, in much the same way as a spinning gyroscope precesses in the earth’s gravitational field (Figure 1). The frequency of precession depends on the strength of the external magnetic field, as described by the Larmor equation, the central equation of MRI:
Richard J Hodgson
Abstract
u ¼ g$B
Magnetic resonance imaging is widely used in the investigation of disorders of the musculoskeletal system. When a patient is placed in a strong magnetic field a signal can be obtained, the frequency of which is related to the strength of the magnetic field. By changing the field strength so it depends on location, it is possible to create an image of the patient. The image intensity depends on several inherent properties of the tissues including hydrogen content, and T1 and T2 relaxation times. MRI is uniquely able to control the sensitivity of the image to these properties to generate different types of image contrast, including T1, T2 and proton density weighting, with and without fat suppression. The most appropriate image for a particular application is a compromise between the conflicting requirements of image resolution, time and image quality. A number of artefacts including chemical shift, metal and magic angle artefacts may degrade images of the musculoskeletal system; however these can be minimized by appropriate choice of imaging parameters. Newer techniques such as delayed gadolinium enhanced MRI of cartilage, dynamic contrast enhanced MRI and ultrashort echo time imaging are now becoming available and these further extend the capabilities of MRI.
where: u is the frequency of precession; g is a constant known as the gyromagnetic ratio; B is the strength of the external magnetic field. In the presence of an external magnetic field there are slightly more protons aligned in the low energy state with the magnetic field than against it, giving rise to a net magnetization in this direction. If a second, much weaker, magnetic field (B1) is applied at 90 to the first field and oscillated at a frequency which precisely matches the frequency of precession (the resonant frequency), the proton magnetization will spiral down into a plane perpendicular to the external magnetic field (Figure 2). At this point, the magnetization from all the protons is aligned. The oscillating B1 magnetic field required to achieve this is known as a 90 excitation pulse. If the B1 magnetic field is then removed, the magnetization continues to rotate about B0, at 90 to it. This rotating magnetization can be detected by placing a radiofrequency coil near to the patient, where the proton magnetization behaves like a rotating magnet in a dynamo, inducing a signal in the coil, which can be measured. Thus, after applying an oscillating magnetic field of the resonant frequency to a patient in a magnet, a signal can be detected from hydrogen nuclei at the same frequency, a frequency which depends on the strength of the magnet.
Keywords image artefacts; image contrast; MRI; MR physics; T1; T2
Introduction Magnetic resonance imaging is a non-invasive imaging technique with many orthopaedic applications. This article aims to provide an introduction to the basic physical principles of MR image formation and contrast in the musculoskeletal system. MRI produces images of a patient from the hydrogen within their body, mainly from water and fat, by placing the patient in a powerful magnet. The signal intensity depends on several intrinsic tissue properties, and the relative importance of these depends on the precise parameters of the MR imaging procedure, allowing extensive control of the image contrast.
B0
Nuclear magnetic resonance The proton which forms the nucleus of the hydrogen atom has a charge and spin. It therefore possesses a magnetic moment and in the semi-classical model of nuclear magnetic resonance the proton is thought of as a tiny spinning magnet. In the absence of an external magnetic field, the protons are randomly orientated. If an external magnetic field (B0) is applied, for example by placing the patient in the magnet of an MRI scanner, the protons
Richard J Hodgson BM PhD Senior Lecturer in MRI and Honorary Consultant Radiologist, Leeds Musculoskeletal Biomedical Research Unit, Chapel Allerton Hospital, Leeds LS7 4SA, UK. Conflicts of interest: none.
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Figure 1 Spinning hydrogen nuclei precess around the direction of the external magnetic field, B0, at the Larmor frequency, which depends on the strength of the external magnetic field.
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B0
Figure 2 A 90 excitation pulse. Application of an oscillating magnetic field at the Larmor (resonant) frequency for the correct duration rotates the magnetization into a plane which is perpendicular to the static external magnetic field, B0 (left). When the oscillating field is removed, the magnetization rotates in that plane at the resonant frequency (right).
Gradient and spin echoes
will consequently diminish (Figure 3). However, subsequently reversing the field gradients by inverting the current down the gradient coils will cause nuclei on the left of the patient, which were lagging behind, to precess faster than those on the right. The magnetization of nuclei on the left of the patient will therefore start to catch up with that from the right. The net magnetization and hence the signal will increase to a maximum when the magnetization across the patient is in phase again, then start to decrease once more. This refocusing of the NMR signal is known as a gradient echo (Figure 4). The spin echo is an alternative to the gradient echo for regenerating the NMR signal. To create a spin echo following signal decay due to a magnetic field gradient, a second radiofrequency pulse is applied after the initial 90 excitation pulse, instead of reversing the field gradient. This second pulse is twice
The frequency of rotation of the proton magnetization depends on the strength of the external magnetic field, B0, according to the Larmor equation. If the magnetic field across the patient is not uniform, but increases from left to right, for example, the frequency of rotation of the protons will also increase from left to right. Such a non-uniform field may be created by superimposing a small magnetic field gradient on the external magnetic field by passing current down appropriately positioned coils of wire, or gradient coils. Because the hydrogen nuclei on the left of the patient are precessing more slowly than those on the right they will start to lag behind. Hydrogen nuclei at different locations in the patient will therefore move out of phase with each other, and magnetization from different regions in the patient will tend to cancel out; the net magnetization and hence the signal detected
B0
Signal
distance
time
Figure 3 Effect of applying a gradient in the magnetic field across a patient. Hydrogen nuclei in different parts of the patient precess at different frequencies and move out of phase with one another. The net magnetization and hence the signal decays.
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B0
B0 Reverse gradients
Signal
Figure 4 A gradient echo. When a magnetic field gradient is applied, hydrogen nuclei on the left of the patient precess slower than those on the right and move out of phase leading to reduction in the signal. Reversal of the field gradient causes the nuclei on the left to precess faster than those on the right, so they catch up again leading to an increase in signal or gradient echo.
the power of the excitation pulse and hence it causes the magnetization vectors to rotate by 180 . This pulse, (known as a 180 refocusing pulse) reverses the phases of the magnetization so that the fast precessing protons on the right of the patient now lag behind the slowly precessing protons on the left. The protons on the right of the patient therefore start to catch up with those on the left, forming a maximum or spin echo (Figure 5).
Magnetic field gradients may be generated in other directions as well as from front to back across the patient. Three sets of gradient coils are included in MR scanners. These all generate magnetic fields in the same direction as the main static magnetic field, but the gradient of the field, i.e. the direction in which the strength of the field changes may be from either left to right, or front to back, or head to foot. By combining these fields it is possible to generate magnetic field gradients which vary in any direction. The MR scanner achieves this by controlling the amount of current passed through each of the coils. The signal from spin or gradient echoes is usually collected while magnetic field gradients are applied. If a field gradient is present across the patient (in a direction perpendicular to that used for slice selection), for example so the hydrogen nuclei on the left of the patient experience a lower magnetic field than those on the right of the patient (Figure 7), the signal detected from the left of the patient will be at a correspondingly lower frequency, according to the Larmor equation, whereas signal from nuclei on the right of the patient will be at a higher frequency because they experience a higher field. By breaking the signal down into its constituent frequencies (Fourier transformation) it is possible to tell where it comes from in the patient. The process of Fourier transformation is analogous to the process performed by the ear on sound waves, enabling the discrimination of sound of different frequencies. Thus, since there is more tissue in the middle of the patient than at the edges in Figure 7, the Fourier transform of the signal acquired with a field gradient from left to right will show more signal at intermediate frequencies than at low or high frequencies. A graph of signal intensity against frequency represents a 2D profile of the patient in the direction of the field gradient. The process of encoding
Image formation In order to generate an image of a patient it is necessary to localize the NMR signal in space. This is typically done by first selecting only those protons in a thin slice through the patient. The signal from this slice is then spatially encoded in two perpendicular directions, allowing an image to be generated of the slice through the patient. Excitation of the hydrogen nuclei from a patient in a static magnetic field requires an oscillating magnetic field of precisely the correct frequency to match the frequency of precession of the nuclei (the resonant frequency), as discussed previously. If a gradient is generated in the magnetic field across the patient (for example from front to back), the frequency of precession will be different at different positions in the patient. Application of an excitation pulse with a limited range of frequencies or bandwidth will therefore only excite those nuclei with matching frequencies of precession. This results in excitation of a thin slice through the patient (Figure 6). The position of this slice can be controlled by changing the frequency of the excitation pulse; the thickness of the slice can be controlled by changing the strength of the field gradient.
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B0
180 pulse
Signal
Figure 5 A spin echo. When a magnetic field gradient is applied, hydrogen nuclei on the left of the patient precess slower than those on the right and move out of phase leading to reduction in the signal. A 180 radiofrequency pulse inverts the magnetization so that the fast moving nuclei on the right now lag behind the slow moving nuclei on the left. Over time they catch up, so the magnetization comes into phase leading to an increase in the signal or spin echo.
turbo spin echo imaging, where additional 180 refocusing pulses are applied after the signal from the first echo decays to create additional, subsequent echoes while changing the phase encode gradient between them. The method described for imaging a single slice through the body using slice selection, read and phase encoding, can be extended to acquire multiple slices in the same time. While protons from an excited slice are recovering prior to being excited again for the next phase encode step, additional slices may be excited independently. This allows multiple contiguous or nearly contiguous slices through the region of interest to be imaged in the same time period, known as multislice imaging. 3D imaging is an alternative to multislice imaging for acquiring data from a volume of interest. In 3D imaging, instead of selecting a thin slice from the patient, a thick slab is excited. Phase encoding is performed in two perpendicular directions together with read encoding to generate a 3D dataset. 3D Fourier transformation then yields a 3D image. By appropriate choice of the imaging parameters it is possible to obtain an image with isotropic resolution in all three directions which can be reformatted after acquisition to provide images in any plane (Figure 9). Because of the additional phase encode steps, 3D images are typically time consuming or limited in contrast or resolution.
spatial information by application of a field gradient in this way is known as read encoding. Phase encoding is an alternative to read encoding for spatially localizing the MRI signal. In read encoding the signal intensity is measured at multiple time points while the protons precess under the influence of the magnetic field gradient. In phase encoding, after excitation of the magnetization, the magnetic field gradient is applied briefly, then switched off, and the signal acquired in its absence. The process is repeated may times with different magnetic field gradient strengths. This causes the signal intensity to vary between excitations in much the same way as it varies with time after a single excitation under the influence of the read encoding field gradient. Once again, Fourier transformation of the signal generates a profile of the patient in the direction of the gradient of the field. Phase encoding takes considerably longer than read encoding, as the magnetization has to be allowed to recover between excitations. The main use for phase encoding is by combining it with read encoding in a perpendicular direction. The signal intensity acquired under the influence of the read gradient can be stacked up at different phase encoding gradient strengths to make a 2D dataset. The resulting 2D data can be Fourier transformed in two-dimensions to yield a 2D image of the patient (Figure 8). The time required for phase encoding may be reduced by fast or
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T2 and T2* relaxation times. Differences in these properties lead to differences in signal intensity and hence contrast between the various tissues on the image. The relative importance of the different tissue properties to the image contrast depends on the type of imaging sequence used; examples include spin echo, gradient echo and inversion recovery sequences. Parameters such as the repetition time (TR), the echo time (TE) and the flip angle, which may be changed by the MR scanner, also control the contribution of the different MR properties to the image contrast. Fat suppression techniques can be used to eliminate signal from fat.
Field
Proton density Proton density is used to refer to the concentration of hydrogen nuclei in a tissue. Since all the signal in clinical MRI comes from the hydrogen nuclei, the intensity of the MR image depends on the proton density.
distance
Excitation pulse
T1 contrast The T1 or longitudinal or spin-lattice relaxation time of a tissue is a measure of how quickly the hydrogen nuclei realign themselves with the external magnetic field after excitation. T1 values for biological tissues are typically hundreds to thousands of milliseconds, and depend on the strength of the external magnetic field. As multiple excitations are needed for most imaging sequences, the signal from a tissue depends on the T1 relaxation time and the time between excitations or repetition time (TR). If TR is very long, the nuclei in all the tissues in the patient will have time to realign themselves with the static external magnetic field after excitation and the tissue contrast will be independent of T1. However, if TR is short, realignment will be incomplete so less signal will be obtained, particularly from tissues with long T1 relaxation times. Contrast between tissues with different relaxation times will therefore increase as the TR is decreased. For example, synovial fluid has a longer T1 relaxation time than articular cartilage. MR images obtained with long relaxation
frequency Figure 6 Slice selection. In order to excite the hydrogen nuclei in the patient, the frequency of the excitation pulse must match the frequency of precession of the nuclei. Application of a field gradient across the patient means a different frequency of excitation pulse is required in different regions of the patient. An excitation pulse made up of only a narrow range of frequencies will therefore only excite a thin slice in the patient (corresponding to the yellow slice in the figure).
Image contrast The brightness or darkness of the representation of a tissue on an MR image reflects the intensity of the signal detected from it. This signal intensity depends on several intrinsic MR properties of the tissues including the concentration of hydrogen nuclei and T1,
Patient
Patient
B0
B0
distance Signal
distance Signal
frequency
frequency
Figure 7 Read encoding. Fourier transformation of the signal acquired while a magnetic field gradient is applied leads to a profile of the patient in the direction of the field gradient.
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Figure 8 A 2D image is created by spatially encoding the signal with a read encoding gradient in one dimension and multiple phase encoding gradients in another. 2D Fourier transformation of the signal data gives an image.
times may show them with similar signal intensities; however as TR is reduced, the signal intensity from the synovial fluid decreases more than that from cartilage, so contrast is increased with fluid appearing darker than cartilage. Figure 10 shows how contrast between fat and muscle increases at shorter repetition times. There are limits to how far the repetition time can be reduced; however, as all images contain noise within them and if the repetition time is too short noise will dominate the signal from the tissues. Gradient echo images can also show T1 contrast; however the situation is more complicated as the angle between the static external magnetic field and the magnetization due to excitation (the flip angle) may also be changed. If the hydrogen magnetization is excited until it makes an angle of 90 to the static external magnetic field, the signal detected from the patient is maximized, but a long repetition time is needed between excitations, increasing the time needed to acquire the image. Reducing the flip angle in gradient echo images reduces the time taken for the magnetization to realign itself with the external magnetic field. This reduces T1 contrast in the images; alternatively, shorter repetition times may be used and the imaging time can be reduced. Gradient echoes are therefore often used for 3D imaging where more phase encoding steps are required. Images with strong T1
contrast may be generated by using short repetition times and high flip angles. To minimize confounding effects of T2 relaxation, short echo times are often used (see below). Magnetic field variations due to molecular motion promote T1 relaxation. The effect is greatest when motion occurs near the Larmor frequency, for example in fat molecules, which consequently have short T1 relaxation times. T1 in free water such as synovial fluid or the nucleus pulposus of intervertebral discs is longer. T2 contrast The T2 or transverse or spin-spin relaxation time is a measure of how quickly the hydrogen nuclei move out of phase with one another. Immediately after the 90 excitation pulse, all the nuclei are in phase with one another, precessing with the Larmor frequency. However, some move faster than others as they exchange energy causing them to move out of phase with one another. This dephasing is not refocused by either the 180 pulse in a spin echo or the reversal of the field gradients in a gradient echo. It therefore causes in a reduction of the signal intensity measured at the echo. The reduction is greater in tissues with a shorter T2. The size of the effect depends on the time between excitation and the formation of the echo, the echo time, TE. At
3D images. Sagittal, coronal and axial reconstructions from a 3D dataset of the knee in a patient with a radial tear of the lateral meniscus (arrow). Figure 9
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Long repetition time Poor T1 contrast
Signal
Short repetition time Good T1 contrast Repetition time Figure 10 T1 contrast. Schematic graph of signal intensity vs. repetition time for muscle (long T1, blue) and fat (short T1, red). Signal intensity of fat is greater than that of muscle. The difference in signal intensity and hence the contrast between the two tissues is greater at short repetition times due to the difference in their T1 relaxation times.
short echo times, the effect of T2 is relatively small. At longer echo times, tissues with a long T2 still give a large signal, whereas those with a short T2 give much less signal. Consequently, T2 contrast increases as the echo time increases. For example, synovial fluid has a longer T2 relaxation time than cartilage. At short echo times both synovial fluid and cartilage appear with high signal intensity and there is little contrast between them. At long echo times, however, the signal from the
Signal
cartilage has decayed much more than that from the synovial fluid and contrast between them is improved. Again, background noise limits how long the echo time can be before noise dominates the signal from the tissues. Figure 11 shows how synovial fluid, with its long T2 relaxation time, becomes more prominent on the long TE images. The same mechanisms which contribute to T1 relaxation also promote T2 relaxation. In addition, static field gradients can
Short echo time Poor T2 contrast
Long echo time Good T2 contrast
Echo time Figure 11 T2 contrast. Schematic graph of signal intensity vs. echo time for synovial fluid (long T2, blue) and cartilage (short T2, green). Signal intensity of fluid (black arrow) is greater than that of cartilage (white arrow). The difference in signal intensity and hence the contrast between the two is greater at long echo times due to the difference in their T2 relaxation times.
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known as T1 weighted images. Images with a long repetition time and a short echo time are relatively insensitive to both T1 and T2 and are known as proton density images. In fast spin echo imaging, multiple echoes at different times contribute to the final image and the net effective echo time is a complex combination of the individual echo times. Inflammation and oedema in tissues tend to increase both T1 and T2 relaxation times, leading to reduced signal on T1 weighted images and increased signal on T2 weighted spin echo images. T2 weighted images tend to be more sensitive for detecting pathology than T1 weighted images.
fat Signal
muscle
Inversion time
TI
T2* contrast The magnetic field in a patient is not completely uniform but varies slightly from place to place, even in the absence of imaging field gradients. Inhomogeneities due to the external magnetic may be minimized, but variations in the field are also induced by the patient themselves, due to small-scale differences in the intrinsic magnetic properties of different tissues in the body, called magnetic susceptibility. These effects lead to additional dephasing. This is refocused by a 180 pulse and so has little effect on spin echo images. However, in gradient echo images, the susceptibility effects remain and cause loss of signal at the echo in addition to that due to T2 relaxation. The combined effects of T2 and susceptibility are characterized by the T2* relaxation time, where T2* is always less than T2. Contrast in gradient echo images therefore depends on T2*, rather than T2. T2* contrast is greater at longer echo times. Susceptibility effects are largest at tissue interfaces, particularly between calcified trabeculae of bone and the surrounding marrow. Signal intensity of trabecular bone is therefore lower on gradient echo images than spin echo images.
Figure 12 Short tau inversion recovery (STIR) imaging. Graph of signal intensity vs. inversion time for muscle (long T1, blue) and fat (short T1, red). The signal intensity depends on the inversion time TI and the T1 of the tissue. At short inversion times without T1 relaxation all tissues give large (negative) signal. At long inversion times there is complete T1 relaxation and all tissues give a large (positive) signal. At the appropriate inversion time, signal from the fat (red), with its short T1, is nulled, whereas signal from other tissues with longer relaxation times, such as muscle (blue), is not.
cause T2 relaxation, so T2 is always shorter than T1. T2 tends to be long in freely moving water such as in synovial fluid and shorter in more tightly bound hydrogen nuclei such as those in macromolecules. Some tissues, such as cortical bone and normal tendons, have T2 relaxation times which are so short they cannot be visualized with conventional MRI. Typically, pathological changes such as inflammation within a tissue lead to an increase in free water and an increase in the T2 relaxation time. In order to generate images in which T2 contrast dominates, a long echo time is used to accentuate T2 effects while T1 contrast is minimized by using a long repetition time. These are known as T2 weighted images. To generate images in which T1 contrast dominates, a short repetition time is used to accentuate T1 contrast while T2 effects are minimized by using a short echo time. These are
Fat suppression Fat and water are the major contributors to clinical MR images. Signal from fat may be suppressed either on the basis of its chemical shift or its T1 relaxation time.
Fat suppression. Removal of the signal from fat from images using chemical shift selective fat suppression (left) and STIR (right). There is failure of fat suppression in the fat saturated image on the left at the distal tibia due to field inhomogeneity. The STIR image on the right is more resilient to field inhomogeneity and shows good fat suppression throughout. Figure 13
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The magnetic field a hydrogen nucleus experiences is slightly different to the external magnetic field, due to the effects of surrounding electrons. The electronic configuration depends on the chemical environment of the hydrogen. Hydrogen nuclei of fat therefore experience a slightly different magnetic field to those of water, and consequently they precess at a slightly different frequency (chemical shift). This frequency difference can be used to create images devoid of fat. Water only images can be generated by using an oscillating magnetic field for excitation with a very narrow range of frequencies so only the hydrogen nuclei from water are excited (water excitation). Alternatively, the signal from lipid may be suppressed by exciting the fat prior to imaging and applying magnetic field gradients causing dephasing and signal loss (see Figure 3); the water is then excited in the usual manner before longitudinal relaxation of the fat occurs ( fat saturation). Figure 9 shows an example of fat saturated imaging of the knee; no signal is obtained from the fat, for example in the subcutaneous tissue, Hoffa’s fat pad or the bone marrow, in contrast to the nonfat suppressed images in Figures 10 and 11. These techniques require a very uniform external magnetic field so the fat and water frequencies are consistent throughout the region of the patient which is being imaged. Fat may also be suppressed on the basis of its short T1 relaxation time. Prior to excitation of the hydrogen nucleus for imaging, an oscillating magnetic field pulse is applied to rotate the hydrogen nuclei magnetization 180 so it lies anti-parallel to the external static magnetic field (inversion pulse). This is equivalent to applying two sequential 90 excitation pulses. Excitation immediately after this results in a negative signal (although the sign is not taken into account when the image is displayed). However, if there is a delay between inversion and excitation (the inversion time), the magnetization undergoes T1 relaxation and rotates back towards the equilibrium state, parallel to the external field (Figure 12). After a particular inversion time, which depends on the T1 relaxation time of the tissue, the magnetization will lie perpendicular to the external field. Excitation at this point results in no signal. The inversion time at which this signal nulling occurs depends on the T1 relaxation time of the tissue. Since the T1 of fat is very short, choice of an appropriately short inversion time nulls signal from fat whereas signal from the longer T1 tissues remains. This method of fat suppression is known as Short Tau Inversion Recovery or STIR imaging. STIR imaging is less sensitive to magnetic field inhomogeneities than chemical shift-based techniques and is therefore more robust. A comparison of the different fat suppression techniques is shown in Figure 13.
Figure 14 T1 weighted fat suppressed image after intravenous Gadolinium-DOTA from the knee of a patient with arthritis. There is marked enhancement of the synovitis (black arrow) which appears bright. The suprapatellar effusion (white arrow) does not enhance and appears dark.
arthritis after the intravenous administration of GadoliniumDOTA, showing enhancement of synovitis. Dilute gadolinium chelate solution may also be directly injected into joints in MR arthrography, leading to high signal joint fluid on T1 weighted images which can sensitively outline joint pathology. Risks associated with the use of gadolinium-based contrast agents are low, although recently, they have been linked to nephrogenic systemic fibrosis, particularly in patients with renal impairment.
Exogenous gadolinium-based contrast agents Gadolinium ions are strongly paramagnetic and reduce the T1 (and to a lesser extent the T2) relaxation time of surrounding tissues. In chelated form, such as gadolinium-DTPA or gadolinium-DOTA, they may be administered intravenously. They move from blood vessels into tissues depending on the tissue vascularity, capillary permeability and extracellular fluid volume, all of which may be increased in disease, for example inflammation. The reduction of the T1 relaxation time leads to high signal on T1 weighted images. Fat suppression is often used to distinguish high signal due to contrast enhancement from fat. Figure 14 shows an example of images acquired from the knee of a patient with
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Figure 15 Chemical shift artefact. Image of the distal interphalangeal joint of a finger. The image of the fat is shifted distally compared to the image of the water. The distance between the fatty marrow of the trabecular bone and the articular cartilage of the joint therefore appears increased in the distal phalanx (white arrow) and decreased in the proximal phalanx (black arrow).
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Figure 16 Metal artefact. Axial images through the knees of a patient with bilateral total knee replacements. There are large signal voids around the metal of the prostheses.
Image noise, resolution and imaging time
boundaries between fat and water, only in one direction (the direction of read encoding). Sometimes these artefacts can result in fat obscuring tissues of interest; in these cases fat suppression techniques (Figure 13) may be helpful. Alternatively, the effect may be reduced by increasing the receiver bandwidth, at the expense of more noisy images.
MRI is an inherently noisy technique. Thermal energy causes background noise in the image, limiting the image quality or signal to noise ratio. This depends on several factors. Higher resolution images contain more noise. Increasing the acquisition time by increasing the repetition time or combining repeated images (signal averaging) improves the signal to noise ratio. The final image is therefore a compromise between resolution, signal to noise ratio and acquisition time.
Metal artefact Metal distorts the nearby magnetic field. The degree of distortion depends on the type of metal but can cause major artefacts in the vicinity of metallic orthopaedic implants. This can include extensive signal voids (Figure 16), areas of high signal or image distortion. As with chemical shift artefacts, metal artefact may be reduced by increasing the receiver bandwidth at the expense of image noise. Spin echo images are less sensitive than gradient echo images, and T1 weighted images are less susceptible than T2 weighted images. Fat suppression using chemical shift selective techniques is often unreliable near to metal and STIR may be better.
Imaging artefacts There are a number of artefacts which can affect MR images. Of particular relevance to musculoskeletal imaging are chemical shift, metal and magic angle artefact. Chemical shift artefact Because fat and water precess at slightly different frequencies in the same external magnetic field, the fat image is shifted slightly with respect to the water image (Figure 15). This effect can lead to spurious low signal lines where fat and water are shifted away from each other, or high signal lines where they overlap. Such artefacts are easy to identify because they occur at the
Magic angle artefact Tendons usually appear with low signal intensity on all conventional MRI sequences, due to their very short T2 relaxation times, caused by the highly ordered collagen. However, this is dependent
Figure 17 Magic angle artefact. High signal is seen in the tendon on T1 weighted image as it changes orientation where it makes an angle of 55 to the external magnetic field (arrow).
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Figure 18 dGEMRIC imaging. A colour coded T1 map of the hip acquired 1 h after intravenous contrast agent, for assessment of the proteoglycan content of the articular cartilage.
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0.5
Relative early enhancement rate
0.45 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0
0
2
4
6 8 Time (weeks)
10
12
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Figure 19 Dynamic contrast enhanced MRI. An early enhancement rate map of a patient with rheumatoid arthritis (left). Early enhancement rates are colour coded and superimposed on a standard grey-scale image, showing rapid enhancement of synovitis in the wrist and metacarpophalangeal joints (red/yellow). The graph on the right shows the change in synovial early enhancement rate after TNF blocking treatment.
monitoring cartilage repair.1,2 These include T2 relaxation time measurement and sodium imaging,3 but perhaps the best developed is delayed gadolinium enhanced MRI of cartilage (dGEMRIC).2,4 In dGEMRIC, gadolinium-based contrast agent is administered intravenously then the T1 relaxation time of the cartilage is measured after about 1 h. At equilibrium, the concentration of gadolinium in the cartilage depends on the proteoglycan content. Since gadolinium reduces the T1 of the cartilage, T1 measurements can be used to assess proteoglycan concentration. This has the potential to identify early cartilage changes before irreversible, structural damage occurs.4 Figure 18 shows an example of a dGEMRIC map of cartilage in the hip.
on the orientation of the tendon relative to the static external magnetic field. When the collagen fibres of the tendon make an angle of 55 to the external field, its T2 relaxation time increases many times, causing high signal on short echo time images of the tendon (Figure 17). The effect depends on the angle between the tendon and the static magnetic field, independent of the plane of imaging, so may occur on images of the tendon in cross-section, where its curvature may not be obvious. This artefact can be distinguished from tendinopathy by the 55 angle between the tendon and the static magnetic field and the absence of high signal on T2 weighted images.
Advanced MRI techniques
Dynamic contrast enhanced MRI The early phases of contrast enhancement also provide useful tissue information. If sequential MR images are acquired rapidly (every few seconds) as contrast agent is administered intravenously, the gadolinium uptake rate may be calculated (the early enhancement rate). Such measurements are very sensitive to tissue vascularity and capillary permeability and are therefore likely to be good markers of inflammatory activity. Figure 19 shows an example of the response of the synovial early enhancement rate in patients with rheumatoid arthritis following biologic therapy. The technique can also be used to assess the response of tumours to treatment.5
Most clinical MRI uses standard T1, T2 or proton density weighted images. However there is increasing interest in using more advanced MRI to better characterize the tissues. Examples with the potential for clinical use include methods for cartilage assessment, dynamic contrast enhanced MRI and ultrashort echo time imaging. Cartilage characterization There are a number of techniques for cartilage characterization, many of which have been developed for osteoarthritis research but which may have clinical application, for example for
Ultrashort echo time MRI Tissues such as tendon and bone are difficult to see using conventional MRI because of their very short T2 relaxation times. For example, changes of tendinopathy are not seen until they are sufficiently severe either to cause gross thickening of the tendon or to increase the T2 many times. Ultrashort echo time MRI can directly visualize normal tendon, allowing the assessment of more subtle changes.6 Figure 20 shows an example of such changes in a patient with spondyloarthritis.
Conclusion Magnetic resonance images are generated from the hydrogen nuclei in a patient. The signal intensity in the images reflects intrinsic properties of the tissues which change in disease, allowing visualization of pathology as well as anatomy. T1, T2 and proton density weighted images are commonly used, with or without fat
Figure 20 Ultrashort echo time imaging. Enhancing tissues appear bright after intravenous contrast agent. There is abnormal enhancement within the Achilles tendon (arrow) in this patient with spondyloarthritis.
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2 Burstein D, Gray M, Mosher T, Dardzinski B. Measures of molecular composition and structure in osteoarthritis. Radiol Clin North Am 2009 Jul; 47: 675e86. 3 Potter HG, Black BR, Chong le R. New techniques in articular cartilage imaging. Clin Sports Med 2009 Jan; 28: 77e94. 4 Pollard TC, McNally EG, Wilson DC, et al. Localized cartilage assessment with three-dimensional dGEMRIC in asymptomatic hips with normal morphology and cam deformity. J Bone Joint Surg Am 2010 Nov 3; 92: 2557e69. 5 Bakhshi S, Radhakrishnan V. Prognostic markers in osteosarcoma. Expert Rev Anticancer Ther 2010 Feb; 10: 271e87. 6 Robson MD, Benjamin M, Gishen P, Bydder GM. Magnetic resonance imaging of the Achilles tendon using ultrashort TE (UTE) pulse sequences. Clin Radiol 2004 Aug; 59: 727e35.
suppression. Intravenous contrast agents may be useful for highlighting areas of abnormal vascularity. The optimum image is a compromise between resolution, acquisition time and image noise. A number of artefacts can degrade MR images, however these may be minimized and are straightforward to recognize; metal artefacts in particular limit the usefulness of postoperative MRI. MRI is continually developing and new techniques for quantifying and improving image contrast are becoming available. A
REFERENCES 1 Trattnig S, Domayer S, Welsch GW, Mosher T, Eckstein F. MR imaging of cartilage and its repair in the knee e a review. Eur Radiol 2009 Jul; 19: 1582e94.
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SYNDROME
surgeon who described a case in 1891.1 This was not the first report however.2e5 The scapula is dysplastic, particularly the supero-medial corner and mal-positioned. Characteristically there is an omovertebral bone; a fibro-osseous connection between the cervical spine and scapula. The deformity is most frequently mild but when severe may cause cosmetic distress or functional deficit. Analysis of William Shakespeare’s descriptions of Richard III suggests that this was King Richard’s physical affliction.6 He is described as “a valiant crook-back prodigy”, of slight build, for which he compensated by undertaking vigorous exercise, especially fighting. He did not appear functionally compromised. In this article the deformity will be discussed along with the possible surgical treatments and their indications.
Sprengel’s deformity Lucy Radmore William Thomas Andrew Tasker Donna Diamond Rouin Amirfeyz Martin Gargan
Abstract Sprengel’s deformity is a congenital dysplasia of the scapula characterized by scapular elevation, rotation and characteristically, an omovertebral bone. Cases may appear in the FRCS (Trauma & Orth) exam. This article reviews the deformity and management principles.
Associations Sprengel’s shoulder is rare but is the most common shoulder girdle deformity.7 It is associated with vertebral and rib deformities, scoliosis, spina bifida and abnormal musculature torticollis.8,9 Between 20 and 42% of patients with KlippeleFeil syndrome also have a Sprengel’s deformity.8,10 It is equally frequent in males and females.
Keywords congenital elevation of the scapula; omovertebral bone; omovertebral connection; KlippeleFeil syndrome; Sprengel’s deformity; Sprengel’s disease; Sprengel’s shoulder
Introduction Aetiology
Congenital elevation of the scapula has gained the eponymous name of Sprengel’s after Otto Gerhard Karl Sprengel, a German
The aetiology of Sprengel’s deformity is yet to be fully elucidated. It has been described as an undescended scapula, with arrest of the normal embryological descent, leaving the scapula high on the chest wall.11 Horwitz proposed oligohydramnios12 and Engel described a cerebrospinal ‘bleb’, probably of neural crest origin as the primary defect. Evidence for these causes has been unconvincing. A molecular biological study has implicated the axial skeleton of neural crest origin in the development of Sprengel’s deformity, KlippeleFeil syndrome and Arnold Chiari I/II syndrome.13
Lucy Radmore BMBS BSc Core Trainee in Trauma and Orthopaedics, Department of Trauma & Orthopaedics, Bristol Royal Infirmary & Bristol Royal Hospital for Children, Upper Maudlin Street, Bristol BS2 8HW, UK. Conflicts of interest: none. William Thomas MRCS MBBS BSc SpR in Trauma and Orthopaedics, Department of Trauma & Orthopaedics, Bristol Royal Infirmary & Bristol Royal Hospital for Children, Upper Maudlin Street, Bristol BS2 8HW, UK. Conflicts of interest: none.
Pathoanatomy
Andrew Tasker MRCS MBBS SpR in Trauma and Orthopaedics, Department of Trauma & Orthopaedics, Bristol Royal Infirmary & Bristol Royal Hospital for Children, Upper Maudlin Street, Bristol BS2 8HW, UK. Conflicts of interest: none.
The scapula in Sprengel’s is dysplastic, in an abnormal, elevated and adducted position.8,11,14,15 Presence of an omovertebral connection that originates from the cervical vertebral spinous processes and attaches to the scapula occurs in 20e25% of cases and is diagnostic.8,9,12,15 Variable attachments to the scapula are described including a true joint, pseudoarthrosis, synostosis and a fibrous band.9 It is thought that the position on the scapula of this connection determines the shape, rotation and superior displacement of the scapula16 with consequent reduction of glenohumeral abduction.11 On plain radiographs the scapula appears small and until recently it has been taken to be hypoplastic.11 A 3D-CT study of 15 patients however found that affected scapulae were in fact larger with a characteristic shape and a decrease in the height to width ratio.16 There was an inverse relationship between scapular rotation and superior displacement and no significant difference in glenoid version (although the authors note that the glenoid is not fully ossified in this age group).
Donna Diamond DCR(R) Superintended Paediatric Radiographer, Department of Trauma & Orthopaedics, Bristol Royal Infirmary & Bristol Royal Hospital for Children, Upper Maudlin Street, Bristol BS2 8HW, UK. Conflicts of interest: none. Rouin Amirfeyz FRCS(Trauma & Orth) Upper Limb Fellow, Department of Trauma & Orthopaedics, Bristol Royal Infirmary & Bristol Royal Hospital for Children, Upper Maudlin Street, Bristol BS2 8HW, UK. Conflicts of interest: none. Martin Gargan FRCS(Trauma & Orth) MA Consultant Paediatric Orthopaedic Surgeon, Department of Trauma & Orthopaedics, Bristol Royal Infirmary & Bristol Royal Hospital for Children, Upper Maudlin Street, Bristol BS2 8HW, UK. Conflicts of interest: none.
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SYNDROME
Clinical features The deformity is present at birth and progresses with development. Cosmetic asymmetry and functional impairment may be apparent but are rarely significant before the child’s first birthday. First presentation is usually in the first or second year of life. The glenohumeral joint develops normally and reduced shoulder abduction is partly a product of a scapular rotation but mainly due to limited scapulothoracic motion. This is a functional impairment that is generally well tolerated. Sprengel’s shoulder is nearly always associated with other congenital malformations.8 It is important to be mindful that, when considering surgical correction, these other deformities will persist. The severity of the deformity can be graded using a clinical classification devised by Cavendish8 and the Rigault radiographic classification.17 Both are used to support surgical intervention and to a lesser extent, success of surgery (Figures 1 and 2).
Figure 2 X-ray of a patient with bilateral Sprengel’s and omovertebral bones.
co-morbidities and the child’s age. When surgery is for cosmetic gains alone, the patient and carer’s expectations must be carefully managed. Concurrent deformities will likely persist along with an unsightly surgical scar. The increased complexity of operating on young children, when structures are small, is weighed against the greater risk of brachial plexus injury and deformity recurrence in older children.8,18 The optimal age is controversial but most authors agree that surgery has best results when performed between 3 and 8 years.19 Corrective operations range from simple excision of the superior angle of the scapula8,20 (associated with very high recurrence rates) to subtotal scapulectomy9,21 (associated with poor functional outcome). Contemporary surgical procedures are based on one of three operations and their modifications: Green’s procedure Woodward’s procedure Scapular osteotomy
The Cavendish classification8 C Very mild, shoulder level and deformity invisible when dressed C Mild, shoulders almost level, lump visible in web of the neck when dressed C Moderate, shoulder elevated 2e5 cm. Deformity easily visible C Severe, superior angle of scapula near occiput, with or without neck webbing The Rigault classification17 C Supero-medial angle lower than T2 but above T4 transverse process C Supero-medial angle located between C5 an T2 transverse process C Supero-medial angle above C5 transverse process
Green’s procedure22 is an extraperiosteal, periscapular muscle release. The skin incision is long, curving around the superomedial scapular corner and finishing 5 cm below the inferior angle. The surgical dissection is demonstrated in Figure 3. The
Management The indications for surgery are functional impairment and cosmetic dissatisfaction. When symptoms are minimal, no intervention is required. When considering surgery, the surgeon should consider the associated congenital abnormalities, medical
Figure 1 X-ray of a Child with unilateral Sprengel’s.
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Figure 3 Posterior view of omovertebral bar.
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periscapular muscles are taken off from their insertion into the scapula, facilitating excision of the dysplastic superior medial corner and omovertebral connection. The scapula is displaced distally and held. In their original description, a percutaneous wire was employed, attached to the tip of the scapula and held by a spring balance to a spica plaster cast. Modifications of the procedure avoid this percutaneous wire by securing the inferior scapular angle either into a pocket of latissimus dorsi or directly onto the thoracic cage.14 Although these techniques reduce scapulothoracic motion, they permit early rehabilitation and are more acceptable to the patient and family.
medial fragment is reduced distally allowing extraperiosteal dissection of the tensioned soft tissues from the dysplastic supero-medial scapular border. The omovertebral bone is then excised extraperiosteally along with the superior scapular angle. Adhesions deep to the lateral fragment are bluntly taken down enabling displacement of the fragments and re-alignment of the offset holes which are then secured with heavy, non-absorbable sutures.
Rehabilitation The described postoperative rehabilitation is most cautious after Green’s procedure with 4 weeks of shoulder immobilization.14,27 Woodward’s procedure describes waiting only for the wounds to heal before active rehabilitation.15,18,23 The Edinburgh group adopted a similar, accelerated rehabilitation following their scapular osteotomy24 (however previous series have delayed full active rehabilitation for 6 weeks26).
15
Woodward’s procedure retains the scapular muscular insertions and instead addresses their origins. It is performed through a long, midline incision. The surgical dissection is demonstrated in Figure 4. The trapezius is dissected from its spinous process origin in continuity cranially with the rhomboids. The superomedial border and aberrant omovertebral structures are dissected extraperiosteally then excised. The mobile scapula is then reduced caudally and the tough aponeurotic border of the muscle flap is reattached to the spinous processes in the new position, maintaining the reduction. Borges describes23 additional excision of the medial border of the scapula, addressing the abnormal height to width ratio. This resection is an attempt to prevent postoperative apparent winging of the scapula by decreasing its horizontal width. Lastly, a scapular osteotomy24e26 addresses the position of the scapula whilst maintaining the integrity of the periscapular muscle origins and insertions. A longitudinal skin incision is made, 2e3 cm lateral to the midline and is somewhat shorter than those described above. The soft tissues and periosteum are split 1 cm from the medial scapular border in line with the osteotomy. Offset drill holes are made adjacent to the osteotomy line at predetermined distances equal to the required degree of displacement planned, before the osteotomy is completed. The
Outcomes When the complications listed below are avoided, outcome measures are uniformly satisfactory. Shoulder abduction is consistently improved, caudal scapular displacement achieved and improvement of at least one Cavandish Grade is expected irrespective of the procedure performed.15,23,24,27
Complications Brachial plexus palsies, both transient and permanent are reported with each technique.15,19,24,27 The plexus is most at risk during caudal scapular displacement, either due to plexus traction or compression in the thoracic outlet. Great care should be taken not to over-reduce. Alignment of the superior border with the contralateral side produces satisfactory cosmesis with least possible displacement. Robinson28 recognized this complication and suggested a preliminary clavicle resection prior to commencing the scapular surgery. Alternatively, intraoperative somatosensory evoked potential recording has been described with success,29 avoiding routine clavicle surgery. Postoperative scapular winging is common following both Green’s and Woodward type procedures.14,18,23 It may be a result of mechanical or neurological failure of serratus anterior, or as a structural result of the abnormal height to width ratio of the dysplastic scapula (apparent winging), which can be addressed by excision of the medial scapular border.23 Winging has not been reported following scapular osteotomy.24,26 Surgical scars are of particular importance following surgery, particularly when cosmetic appearance is the indication for surgery. Green’s procedure tends to produce a long scar that is prone to hypertrophy. Woodward’s scar is also long, but being midline tends to be less obvious. The scapular osteotomy scar is smaller, but in a similar position to Green’s and prone to hypertrophy. Advocates of the osteotomy suggest that unlike Green’s scars, their’s does not extend into the neck and can be concealed by most summer clothes.26
Summary Sprengel’s deformity is the most common congenital anomaly of the scapula, characterized by a dysplastic, rotated and
Figure 4 Medial dissection showing omovertebral bar.
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13 Matsuoka T, Ahlberg PE, Kessaris N, et al. Neural crest origins of the neck and shoulder. Nature 2005; 436: 347e55. 14 Leibovic SJ, Ehrlich MG, Zaleske DJ. Sprengel deformity. J Bone Joint Surg Am 1990; 72A: 192e7. 15 Woodward JW. Congenital elevation of the scapula. Correction by release and transplantation of the muscle origins e a preliminary report. J Bone Joint Surg Am 1961; 43: 219e28. 16 Cho TJ, Choi IH, Chung CY, Hwang JK. The Sprengel deformity e morphometric analysis using 3D-CT and its clinical relevance. J Bone Joint Surg Br 2000; 82B: 711e8. 17 Rigault P, Pouliquen J, Guyonvarch G, Zujovic J. Congenital elevation of the scapula in children. Anatomo-pathological and therapeutic study apropos of 27 cases. Rev Chir Orthop Reparatrice Appar Mot 1976; 62: 5e26. 18 Carson W, Lovell W, Whitesides TJ. Congenital elevation of the scapula. Surgical correction by the Woodward procedure. J Bone Joint Surg Am 1981; 63: 1199e207. 19 Greitemann B, Rondhuis J, Karbowski A. Treatment of congenital elevation of the scapula. 10 (2e18) year follow-up of 37 cases of Sprengel’s deformity. Acta Orthop Scand 1993; 64: 365e8. 20 McBurney S. Congenital deformity due to malposition of the scapula. N Y Med J 1888; 47: 582e3. 21 Schrock RD. Congenital elevation of the scapula. J Bone Joint Surg Am 1926; 8: 207e15. 22 Green WT. The surgical correction of congenital elevation of the scapula (Sprengel’s deformity). J Bone Joint Surg Am 1957; 39: 1439e48. 23 Borges JLP, Shah A, Torres BC, Bowen JR. Modified Woodward procedure for Sprengel deformity of the shoulder: long-term results. J Pediatr Orthop 1996; 16: 508e13. 24 McMurtry I, Bennet GC, Bradish C. Osteotomy for congenital elevation of the scapula (Sprengel’s deformity). J Bone Joint Surg Br 2005; 87B: 986e9. €nig F. Einc neue operations des angeborenem sculterblattoch25 Ko standes (New operations for congenital scapular elevation). Zentralbl Chi 1914; 40: 530e7. 26 Wilkinson JA, Campbell D. Scapular osteotomy for Sprengel’s shoulder. J Bone Joint Surg Br 1980; 62: 486e90. 27 Andrault G, Salmeron F, Laville JM. Green’s surgical procedure in Sprengel’s deformity: cosmetic and functional results. Orthop Traumatol Surg Res 2009; 95: 330e5. 28 Robinson R, Braun R, Mack P, Zadek R. The surgical importance of the clavicular component of Sprengel’s deformity. J Bone Joint Surg Am 1967; 49-A: 1481. 29 Shea KG, Apel PJ, Showalter LD, Bell WL. Somatosensory evoked potential monitoring of the brachial plexus during a Woodward procedure for correction of Sprengel’s deformity. Muscle Nerve 2010; 41: 262e4.
undescended scapula with or without an aberrant omovertebral connection or other structural abnormalities. Most cases need no intervention but when function or aesthetics are significantly compromised, surgery is indicated. Successful surgery relies on careful patient selection in terms of associated structural abnormalities, medical co-morbidities, functional abilities and the child’s age; along with management of patient and carer’s expectations. Risk of brachial plexus injury during caudal scapular displacement can be reduced by either by performing a clavicle osteotomy or intraoperative plexus monitoring. Reported outcomes are similar for each of the surgical technique described. A
REFERENCES 1 Sprengel O. Die angeborene vershiebung der schulterblattes nach oben. 1891; 42: 545. € lliker T. Mittheiglungen aus der chirugischen casuistic und kleinere 2 Ko mittheilungern. Bermerkungen zu, aufsatze von Dr Sprengel. ‘Die €r angerborene vershiebung des schulteblattes nach oben’. Archiv fu klinische chirurgie 1981; 42: 925 (Remarks to an essay by Dr Sprengel). 3 Willett A. An account of the dissection of the parts removed after death from the body of a woman, the subject of congenital malformation of the spinal column, bony thorax and left scaplar arch. In: Medico-Chirugical transactions second series 1880; vol. 45. p. 513. 4 Willett A, Walsham W. A second case of malformations of the left shoulder-girdle. BMJ 1883; 1: 513. 5 Eulenburg M. Neitrag sue dislocation der scapula Amtliche berichte €ber due versammlungen deutscher naturoscher und aerzte fu €r die u jahre (Official reports of the meetings of German physicians). 1863; 37: 291. 6 Rhodes P. Physical deformity of Richard III. BMJ 1977; 2: 1650e2. 7 Pinsky HA, Pizzutillo PD, Macewen GD. Congenital elevation of the scapula. Orthop Trans 1980; 4: 288e9. 8 Cavendish M. Congenital elevation of the scapula. J Bone Joint Surg Br 1972; 54: 395e408. 9 Jeannopoulos C. Congenital elevation of the scapula. J Bone Joint Surg Am 1952; 34 A: 883e92. 10 Hensinge Rn, Lang JE, Macewen GD. KilippeleFeil syndrome e constellation of associated anomolies. J Bone Joint Surg Am 1974; A 56: 1246e53. 11 Grogan DP, Stanley EA, Bobechko WP. The congenital undescended scapula e surgical correction by the Woodward procedure. J Bone Joint Surg Br 1983; 65: 598e605. 12 Horwitz E. Congenital elevation of the scapula e Sprengel’s deformity. Am J Orthop Surg 1908; S2-6-2:260e311.
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REHABILITATION
Upper limb prosthetic rehabilitation
upper limb deficiency. The aim is to provide an overview of rehabilitation based on the World Health Organisation (WHO) International classification of Functioning, Disability and Health (ICF) model2 shown in Figure 1 below. In some cases surgical reconstruction of the affected limb may be an option and comprehensive reviews of this area can be found elsewhere.3,4 The more proximal the amputation or congenital absence, the less likely it is that reconstructive surgery will be applicable. In cases where surgical intervention has created a prehensile hand, prostheses will not be required. The ICF model is a distinctly different model of health care compared to a conventional medical model: it is a cause-based model, which emphasizes health condition or disease. However we would all recognize that the same health condition affects people in different ways depending upon a range of factors including co-morbidities, age, physical and social environment and psychological status. This concept is especially relevant in chronic conditions. In rehabilitation, it is the functional impact of a disease that is emphasized. By shifting the focus from cause to impact of disease, it places all health conditions on an equal footing and identifies opportunities for managing the condition and optimizing function when a cure is not available. Compared with those with lower limb amputation, people with upper limb amputation are in a very different situation with respect to body image and social response. Although their mobility is not affected, it is much more difficult to disguise the amputation with clothing, for instance. This may also have cultural implications. In Western society it is very common to start a conversation with a handshake and physical differences will be immediately apparent for an upper limb amputee, more so for a bilateral amputee. Loss of the dominant hand also means patients will have to relearn even the simplest of tasks. Rehabilitation is not only about the provision and maintenance of prostheses. Upper limb services also provide advice and treatment in the management of pain, amputation stump skin problems and vocational choices. In cases of elective or planned amputation, a pre-amputation consultation can be arranged to aid understanding of the implications of undergoing an amputation including the likelihood of phantom pain, the likely functional outcome and insight into the rehabilitation process. A similar consultation is available to parents of children with congenital limb deficiency either before or after birth. Upper limb rehabilitation is a highly specialized discipline, which is only offered in the larger supraregional centres in the UK. In general the limbs that are prescribed are expensive and require a level of upfront investment for assessment purposes, which only the larger centres can offer. Private prosthetic providers operating outside the NHS can provide upper limb prostheses but the NHS treats by far the majority of patients.
Sachin Watve Greg Dodd Ruth MacDonald Elizabeth R Stoppard
Abstract This article describes principles of rehabilitation, according to the ‘international classification of functioning’ model, for people who either required upper limb amputation or have a congenital absence. It also provides a description of current clinical practice at one of the largest prosthetic service providers in the UK. The aim is to provide an overview for any health professional who may work with people with upper limb deficiency as well as providing sufficient details to be useful to those already working in the speciality. Even with clinical advances, upper limb prostheses are often not what a prospective user may imagine. Clinicians need to be sensitive to this at the first consultation and when demonstrating prosthetic limbs. For instance, terminal devices including a split hook are still commonly used to provide useful power or precision grip in highly skilled manual work e.g. joinery. The development of a perfect prosthetic hand in both appearance and function, not to mention texture and warmth of a natural hand, remains a holy grail.
Keywords absence; amputation; congenital; deficiency; extremity; limb; prosthesis; prosthetic; rehabilitation; upper
Introduction The process of rehabilitation assists people to achieve functional goals in their chosen activities and roles. Many conceptual frameworks have been developed to describe the connections between health, disability and society (for example the Social Model of Disability; the Nagi model1). This article focuses on rehabilitation following upper limb amputation or congenital
Sachin Watve MBBS MRCS D.Ortho Registrar Rehabilitation Medicine, Chapel Allerton Hospital, Leeds LS7 4SA, UK. Conflicts of interest: none. Greg Dodd MBAPO SR. Pros/Orth Specialist Prosthetist in Upper Extremity Prosthetics, Specialist Rehab Services, Seacroft Hospital, York Road, Leeds, LS14 6UH, UK. Conflicts of interest: none.
Health condition
Ruth MacDonald Dip COT BSc (Hons) Dip MEd Prosthetic Occupational Therapist Specialist Rehab Services, Seacroft Hospital, York Road, Leeds LS14 6UH, UK. Conflicts of interest: none.
Upper limb amputation is less common than lower limb amputation. In 2006e2007, 7% of all referrals to UK amputation services were for upper limb loss, where upper limb amputation represented 4% and congenital absence 3%.5 The previous year, 2004e2005, the total number of referrals for upper limb loss was 267. Upper limb amputations can be classified according to cause or level and tend to be in the younger age groups, reflecting the
Elizabeth R Stoppard MBChB MRCP Consultant in Rehabilitation Medicine, Specialist Rehabilitation Service, Seacroft Hospital, York Road, Leeds LS14 6UH, UK. Conflicts of interest: none.
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Health Condition E.g. diabetes or vascular disease or, in case of trauma, no underlying disease
Body function/structure E.g. Upper limb amputation, pain, low mood, contracture
Activities E.g. Driving tractor, fence repair, dressing, washing up
Participation E.g. Farmer, employee, student, spouse
Environmental
Personal
Factors
Factors
E.g. Isolated home, bathroom facilities
E.g. Concern for appearance, experience of illness
Figure 1 The World Health Organisation classification of functioning, disability and health.
aetiology of the condition. Almost three quarters of all upper limb referrals were aged less than 55 years.5
widely available. There have been concerns about the potential impact of the reintroduction of thalidomide and whether current surveillance of congenital limb deficiency will be adequate.7
Cause After congenital deficiency, trauma is the next commonest aetiology (approximately 60% of acquired upper limb loss) followed by neoplasia and dysvascularity. Trauma is most commonly seen in work-related accidents (e.g. the hand when clothing becomes trapped in machinery, farming accidents) and road traffic accidents. Congenital deficiencies of the upper limb accounted for 58.5% of all newborn limb-deficiency discharges in a US study.6 Among those, longitudinal hand reductions were most frequent, accounting for 46.4% of upper limb anomalies. Therefore absence of the hand and some forearm is seen in about a quarter of all cases of congenital limb deficiency. In most cases the underlying reason for attenuated development in-utero is unknown and in the vast majority of cases are an isolated unilateral problem. It is rarely associated with a syndrome. Amniotic band formation, though a well recognized phenomenon, is rare (1 in 15 000 live births). Meningococcal septicaemia is associated with necrosis of the extremities, which may lead to auto-amputation or the requirement for surgical amputation. This devastating illness accounts for some cases of multiple limb loss in both adults and children and most centres in the UK will care for at least one person with all four limbs lost due to meningitis. In the 1960s, Thalidomide, promoted as a treatment for nausea in pregnancy, caused limb deficiencies in thousands of infants worldwide. The limb deficiencies were frequently of the intercalary type. Recent studies have shown that Thalidomide may be beneficial for a range of conditions, including Crohn’s disease, leprosy and HIV/AIDS, and it may once again become
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Level As evident in Figure 2, 43% of all upper limb referrals are for trans-humeral or trans-radial limb loss/deficiency. Partial hand and upper digit amputation account for a further 41% of referrals.
Body function/structure In the ICF model, amputation is an impairment at the level of body function/structure. From the rehabilitation point of view, it is important to be always thinking ahead with regard to
Transradial, 18%
Upper digits, 27% Elbow disarticulation, 1% Double upper amputation, 4% Forequarter amputation, 4% Wrist disarticulation, 1% Partial hand, 14% Transhumeral, 25%
Figure 2 The relative frequency of amputations at different levels in the upper limb.5
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optimizing function when an amputation is planned. This often means being aware of how someone will manage wearing a prosthesis and what can be done to facilitate this when fashioning the amputation stump.
traction, shear and perspiration. Intact normal skin also has the great benefit of sensory feedback when a prosthesis is not being worn. Muscle preservation is relevant for use of electronic prostheses, which make use of electrodes placed on the skin over muscle. Myoplasty and myodesis allow useful muscle contraction, as well as providing a stable and reliable underlying shape to the limb. A dumbbell-shaped limb should be avoided, as it is difficult to suspend a prosthesis when the proximal diameter of the limb is less than the distal diameter. Controlled muscle contraction facilitates use of a myoelectric prosthesis. An obvious point is that bone ends need to be bevelled otherwise pain and skin ulceration can occur. Osseo-integration is an innovative surgical approach under development, which uses titanium implants. The titanium integrates into the bone and into the skin giving a stable fixation for a prosthesis. However, infection, although now better managed, may still become a problem. Overall the risk benefit ratio is such that osseo-integration is not offered routinely.
Pre-amputation stage As a general rule it is never too early to involve the rehabilitation team and if possible, patients should be offered the opportunity to meet the rehabilitation team prior to a planned amputation. Exchange of information helps allay anxiety and allows evaluation of the patient’s expectations and needs. Consultation with the multidisciplinary amputation rehabilitation team at this stage may also assist surgical decisions, such as deciding on the optimal level of residual limb if prosthetic use is anticipated. Peer support by someone with amputation at a similar level can be helpful, and this can be arranged through the centre or the service user groups aligned with most centres.
Surgical procedure
Problems affecting prosthetic use Overgrowth of long bones in relation to skin is most commonly seen in acquired amputation in children. Overgrowth has been reported in congenital limb deficiencies, but is rare. This may require surgical revision several times before skeletal maturity. It should be remembered that the residual limb after amputation in a child will not grow as much as the unaffected side and when deciding on how much to shorten, this should be taken into account. An average length residual limb in a child can end up as a very short limb in adult life, making suspension of the prosthesis more difficult. Bony spurs in adults are managed by modification of prosthetic fit in the first instance but may need surgical removal if there is ongoing pain or skin breakdown.
For the most part, surgical procedures in upper limb loss will come under one of the following areas. Creating a prehensile hand This may be considered when the amputation is at hand level in both congenital and acquired amputation. Some plastic surgery centres can assess for toe transfer surgery (usually to fashion a thumb). In the past the Krukenberg procedure was sometimes considered, where the ulna and radius are divided with skin coverage over both, to give the ability to ‘grip’. However this is not cosmetically satisfactory and more recent prosthetic developments have rendered this option obsolete in routine practice. Upper limb transplantation could be considered as the ultimate ‘treatment’ for amputation. Transplantation can be autologous (reimplantation) or allogeneic (from donor). There are limitations to reimplantation surgery including the extent/time of tissue loss and local availability of microsurgical expertise. Rejection reactions in allogeneic graft are controlled by immunosuppressants. Unlike solid organs, any limb has multiple tissue types, which increases immunogenicity.8 The practical and ethical issues mean that this is a procedure which has only been done in a few cases worldwide.
Facilitating use of a prosthesis Postoperative care A rehabilitation regimen including active and passive range of movement should be encouraged as soon as possible. This will strengthen proximal musculature and minimize the risk of contractures and oedema, optimizing function. Patients with sudden limb loss may experience muscle and posture imbalance and, if this is reported, referral to a physiotherapist with amputee and musculo-skeletal (MSK) experience would be appropriate. Graded compression socks to wear on the residual limb are helpful in preventing oedema. Massaging of the scar with hypoallergenic emollients reduces adherence and sensitivity of skin and prepares the limb for prosthesis use. It also reduces the risk of hypertrophic scarring and assists with psychological adjustment particularly for patients who have great difficulty touching or even looking at their amputation stump.
Preparing for prosthesis use To achieve the best outcome for prosthetic use the following should be one’s aims. The amputation site will be at the middle of a long bone with preservation of as many proximal joints as possible. A short trans-radial limb for example, would make suspension difficult and compromise elbow function, resulting in poorer function. Conversely a long trans-radial limb in an adult would make it impossible to accommodate a functional wrist unit (precluding some components, for example a myoelectric prosthesis) because the forearm would be too long compared with the sound limb. Durable soft tissue cover with minimal scar tissue and a scar that is not directly over a bony prominence will lead to fewer skin problems. Skin grafts may be necessary, particularly if this will allow a longer residual limb, but grafted skin may be more prone to breakdown with prosthetic use as it is subject to
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Pain management Pain in the amputated-limb can occur for different reasons and it is important to identify which apply in order to allow correct management. It is also common following upper limb amputation. In one study of 104 patients, nearly all (90%) of the
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respondents reported pain, with 76% reporting more than one pain type.9 Phantom-limb pain and residual-limb pain were the most prevalent (79% and 71%, respectively), followed by back (52%), neck (43%), and non-amputated limb pain (33%). Although pain in the non-amputated limb was least prevalent, it was reported to cause the highest levels of interference and painrelated disability days. Phantom pain is the sensation of pain perceived in the amputated part and should be differentiated from phantom sensation, an almost universal experience, which describes the feeling that the limb is still present (non-painful sensations include position of limb or tingling). At least half of patients with acquired amputation complain of phantom pain, which tends to be worse in the first year and generally improves with time. It is not reported by people with congenital absence of a limb. Pharmacological treatment is considered if the pain interferes with postoperative mobilization, sleep or activities of daily living. Any chronic pain can significantly affect mood and this should be assessed. The recent NICE guidelines on treatment for neuropathic pain recommend amitriptyline and pregabalin.10 Other treatments used, but which do not have a strong evidence base, are topical treatments (capsaicin cream or lidocaine) and anxiolytics, as well as non-pharmacological approaches. The latter includes transcutaneous electrical nerve stimulation (TENS), decreasing residual limb-oedema, and mirror therapy. The use of a prosthesis also results in less reporting of phantom limb pain. Mirror therapy is a non-invasive treatment and is easier to try with upper compared to lower limb amputation. It appears to work for some individuals but not others but tends to offer relief of pain for the duration of use only. The equipment required is heavy and not portable. Pain in the scar tends to arise from adherent scar tissue, exacerbated by delayed wound healing, and is often triggered by use of the prosthesis because of shear forces on the scar. Massaging the scar with emollients can help mobilize the skin and is advised routinely. Pain in the amputation stump can be associated with bony spurs, recurrence of malignancy (if the aetiology of amputation was malignancy) or neuroma. A cut nerve forms a neuroma, which may become symptomatic when exposed to irritation due to size, adhesions and/or reduced soft tissue cover. Neuromas can be palpable and applied pressure will reproduce symptoms. Neuromas can also produce phantom pain. Treatment options include desensitization, modification of the prosthesis to avoid pressure, injection with anaesthetics/steroids/phenol and surgical removal (with traction on the nerve before cutting).
cotton liners on a daily basis. Skin infections include folliculitis, boils, abscesses and fungal rash and should be treated with appropriate medication. Allergic dermatitis can result from various materials of socks/socket/detergents used to clean socks etc. Trigger factors should be isolated and avoided. Topical steroids may be indicated. Psychological adjustment Those with traumatic amputation appear to be at greater risk of psychological adjustment issues, including altered body image and post-traumatic stress disorder. Anecdotal evidence would suggest high levels of distress in this population, particularly in the context of unplanned surgery. Occasionally a patient will have extreme difficulty adjusting to what has happened and professionals should be alert to this in order to arrange appropriate follow up. This is particularly important for the acute team because individuals affected may not pursue prosthesis wearing and may chose not to attend the prosthetic rehabilitation centre. There is a lack of research evidence about the range of psychological issues faced by patients.
Activity The hand, supported by the arm, undertakes complex functional tasks, therefore replacement is a highly challenging subject. To ensure the correct prosthesis is prescribed, it is essential to listen to the patient’s expectations and have a full understanding of their needs. Factors will include level of amputation and dominant handedness, age (particularly in the case of children), family support, occupation, hobbies and interests. The design of the prosthesis should meet the needs of the patient as closely as possible within the constraints of the technologies that are available, and the limitations of the supply environment.
Types of prostheses There are broadly three groups of upper extremity prosthesis available to both groups of congenital and acquired amputation: cosmetic, body powered and electronic. Each of these groups has subdivisions, and each of these groups may well overlap another, so it is not unusual for a patient to be prescribed from more than one group of prostheses. Cosmetic Where a prosthesis is required for appearance purposes only, a cosmetic prosthesis is provided. Typically this group of prostheses remains non-functional and are shaped and coloured to match the remaining sound arm, with no sophisticated components, thus having the benefit of remaining lightweight. They also perform a passive assistive role to the sound arm, such as pushing open a door or steadying a piece of paper when writing.
Skin problems Wearing a prosthesis creates a microenvironment which is conducive to skin problems, commonly infections and dermatitis. Sweating into the close fitting prosthesis can affect fit and lead to increased shear, which may result in skin breakdown. Excessive sweating can lead to maceration, which predisposes to fungal or bacterial infection. This can be treated by topical antiperspirants but talc should be avoided because, rather than keeping the area dry, it tends to mix with skin secretions and creates a further irritant. Good hygiene is important, which means washing and drying the limb and thoroughly cleaning the prosthesis liner and any
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Body powered This group of prostheses is functional, having an active hand that opens and closes, as shown in Figure 3. The method of activation is by an operating cable, which is tensioned using differential body movements. The hand may be readily removed by the user and replaced with a variety of tools, described as terminal devices, appropriate for their needs. For example a patient who carries out manual work such as joinery may need a variety of
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tolerance, the number and adequacy of control sites and the level of arm loss. Recently the i-Limb hand, invented in Edinburgh by David Gow has become the first commercially available hand prosthesis with five individually powered digits; similar second-generation myoelectric prostheses are being developed by other companies. Currently, most powered artificial limbs are controlled with the surface electromyogram (myoelectric signals) from a remaining pair of agonisteantagonist muscles in the amputated-limb. Targeted muscle reinnervation (TMR) for enhanced prosthetic function is an approach under development in upper limb prosthetic rehabilitation. TMR uses the residual nerves from an amputated-limb and transfers them on to alternative muscle groups that are not biomechanically functional. For example, transferring the median nerve to a segment of pectoralis muscle provides a hand-close myoelectric signal. The patient thinks about closing his or her hand and the median nerve reinnervated segment of the pectoralis muscle contracts. The myoelectric signal from this reinnervated muscle segment is then used to provide a control input to close the motorized hand.11 Similarly, targeted sensory reinnervation (TSR) might potentially be used to provide the amputee a sense of touch in the missing limb.
Figure 3 A body powered prosthesis.
different terminal devices for the different tasks during the working day. Each level of amputation requires a unique suspension system and is prescribed accordingly. Electronic In recent years it has been possible to incorporate electric motors (see Figure 4), and latterly microprocessors, into the manufacture of prostheses, enabling the user to control movement through active muscle contraction. Using a variety of control systems, it is possible to provide electric prostheses which are suitable for a range of occupational, recreational and social activities. A typical method of activation is by positioning electrodes on the surface of the skin over the nearest agonist and antagonist muscle groups. These electrodes are designed to identify the increase in voltage within the muscle when it is contracted; this signal is sent to a transducer, amplified and used to activate the graded opening and closing of the hand. Highly skilled users may progress to additional motors to power elbow flexion and wrist rotation and hand as required. Successful application of an electric prosthesis depends on careful evaluation, patient motivation, accurate fitting and appropriate training. The number of powered components practical for a patient will depend on factors such as weight
Prosthesis for level of amputation Forequarter This is the highest level of upper limb amputation and a prosthesis would need to include all joints, with the prosthetic shoulder being built out to conform to the sound side, thus restoring the appearance and balance of the body. However, due to the weight and limited function, patients frequently elect just to have a shaped shoulder cap to restore the shoulder contour, thus eliminating unnecessary weight. Through shoulder With the clavicle and scapula remaining, it is easier for the patient to support the weight of the prosthesis, therefore there is greater incentive for the patient to use the device. Whilst the control of terminal devices is possible, this remains difficult due to the absence of the humerus. Trans-humeral This level allows various methods of suspending and activating the prosthesis to be adopted and provides a secure fixation for using it for various daily living tasks. Having the ability to flex, extend, abduct and adduct the humerus, the patient is able to exercise adequate control of the prosthesis, and therefore activate appropriate terminal devices (see Figure 5). Elbow disarticulation This level of amputation does not allow a prosthetic elbow mechanism to be fitted to the prosthesis without significantly increasing the length of the upper segment due to a lack of space. Trans-radial Having retained the elbow joint, the patient has greater control when supporting and activating the prosthesis and this level of amputation or congenital absence offers the most useful residual limb for successful prosthetic limb use.
Figure 4 An electronic prosthesis.
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a prosthesis is to cast for one at about 6 months of age and then to allow the child to handle and play with it. Initially they will wear it for only a few minutes from time-to-time, and in a passive assistive function, for example holding a handle of a bucket or basket over the arm during play, or for crawling. This means that the prosthesis is likely to be accepted by the child as a potentially useful tool so that their choice to use one or not later on is a natural step. One of the activities for which some kind of prosthetic adaptation is required is riding a bicycle and this can either be a prosthesis with hand component, which can grip the bike handlebar, or a bespoke arm rest attached to the handlebar which the child can put their arm into. Acquired upper limb loss Adults with acquired upper limb loss frequently work in jobs which involve the use of tools or machinery (unfortunately the source of the limb loss in many of these people). A clear understanding of their role and level of desire to return to the same job is required to assess the most useful type of prosthesis and terminal devices. With respect to the selection of prostheses, the combination of durability, required for occupations as above, and cosmesis is very difficult to achieve. This means that the highly effective cosmetic prostheses, which can look disturbingly life-like separated from their owner, are not able to withstand high impact use. Conversely, terminal devices for occupational use do not usually even resemble a hand.
Figure 5 A prosthesis suitable for trans-humeral amputation allowing various terminal devices to be fitted.
Wrist disarticulation This level of amputation restricts the fitting of a conventional hand without having to increase the length of the prosthesis in relation to the sound arm. Congenital abnormalities of the hand/partial hand Conventional prostheses are not suitable for patients presenting with minor congenital abnormalities, such as the shortening or absence of fingers. There are several simple and effective devices that can be manufactured to enhance dexterity without impeding sensory feedback.
Terminal devices As evident in Figure 6 a large range of different attachments (such as split hook) can be applied to the artificial limb after the removal of the mechanical hand. For example, a beef and arable farmer sustained a traumatic trans-humeral amputation and, after healing and provision of a body powered prosthesis, the therapist and patient worked through exactly what tasks he needed to undertake on the farm. These tasks included machine maintenance, tractor driving, calving, milking, gate lifting and fence repairs. A variety of suitable terminal devices were provided to enable him to continue with his work.
Digital replacement These cosmetic devices may be made from silicone or PVC. They are generally only used as a cosmetic replacement since their presence impedes dexterity. Protective ‘thimble like’ caps may be used to protect the distal end of the fingers when undertaking manual work.
Participation Due to the aetiology and pathology of upper limb loss, people with either acquired or congenital upper limb loss are often children or young adults. The unchanging nature of the impairment means the challenge for the multidisciplinary team is to enable the patient to optimize their abilities at each life stage of development. For example the abilities and demands of a toddler are different even from those of a child starting school and needs change throughout the school career and beyond. Congenital absence An important part of the team’s role is to help the parents and child to anticipate additional demands as the child grows, in order to plan prosthetic requirement. Timely assessment of the patient’s skills and needs is important and regular (at least 12 monthly) planned reviews are advisable. This avoids the ‘fire fighting’ response when a young person presents, say, requesting a limb that will assist on the school skiing trip in 2 weeks time. Infants with congenital limb loss are usually referred early and this should be encouraged. The usual procedure for issuing
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Figure 6 A range of terminal devices that can be fitted to an upper limb prosthesis.
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Assessing patient needs
high school, then to university and on into the working environment. The curricular demands of high school often require additional support, for instance to enable the study of food technology and design technology. This additional support might be provided through the supply of specific terminal devices to facilitate bilateral tasks when preparing food or working with wood, metal and scientific instruments. Occupational therapists can advise on the move to higher education and in identifying possible employment. A patient with the congenital absence of the forearm has recently qualified as an airline pilot and is currently working with one of the larger airlines. Another successfully completed a medical degree and is now practicing medicine. Career planning can be helped by facilitating meetings with fellow patients in various different careers such as law, education or police work and by contact with the local Disability Employment Advisor (DEA).
For the multidisciplinary team to work effectively, individual staff who assess within their professional field must communicate their findings to the rest of the team. In prosthetics, during the process of limb provision (casting, fitting, and delivery), there is the opportunity to complete these assessments over a period of time, thus allowing the establishment of a therapeutic relationship. This takes place over a period of weeks for the first limb, and then over years as the patient returns to the service. For example, the occupational needs of the patient are discussed with the occupational therapist who will ask about activities/occupations that a patient may not have initially identified as targets for rehabilitation, including leisure activities such as computer console games for young children. These are in addition to the more obvious needs such as dressing and meal preparation. All team members are alert to issues of psychological adjustment, but it may be in environments external to the clinic setting that these become more obvious. For example, a child who presents as happy and well adjusted when attending with parents may be a very different child in the school situation. The ability to monitor each child in the school environment is therefore useful, as is access to a psychologist within the team to ascertain if patients require specialized psychological services.
Personal factors Some of the unique issues upper limb amputees encounter are self-esteem and body-image concerns, the impact on appearance and social abilities, secondary post-traumatic adjustments for the majority of traumatic injury patients, and feeling isolated from other upper limb amputees to share experiences.12 Personal factors refer to aspects of an individual’s past experience and personality which contribute to the way that they respond to their situation. Psychological evaluation is an important component of the holistic assessment of the patient. Amputation is an emotional experience; a study by Price and Fisher13,14 supports both upper limb and traumatic amputees as being the most emotionally affected.
Choosing not to use a prosthesis The principle of client-centred practice is fundamental to rehabilitation and jointly agreed goals, reached through a process of multidisciplinary goal setting and outcome measurement, is how this is achieved. For example, a teenager with a congenital partial hand entering High School and attending a family wedding was much more concerned with her role as a bridesmaid than the transition to High School. The obvious prosthetic solution was the provision of a cosmetic hand. However the role of bridesmaid can equally be carried out without a prosthesis and both patient and family needed the opportunity to consider a variety of solutions to the activity, in this case without a prosthesis. It is important to be aware that some activities can be best achieved through a combination of a prosthetic and assistive device. For example, the task of making a sandwich with a transhumeral amputation is helped by the additional provision of a bread buttering board to hold the bread, whilst the jam jar is being held by the mechanical hand.
Environmental factors These relate to how the wider environment impacts upon daily life. Examples range from the physical environment (home and access to public buildings and public transport), support and relationships, wider societal attitudes (for instance acceptance of disabled people in employment or the media) to products and services. These aspects need to be considered with the patient as they adjust to life following the amputation. The rehabilitation team will consider how activities and occupations important to the patient can be carried out in a variety of locations and the most appropriate prosthetic prescription.
Bilateral amputees
Prosthetic services in the UK
In unilateral amputees a prosthesis usually supplements the remaining manual dexterity and sensory feedback of the sound hand. Without this feedback and dexterity, bilateral amputees are significantly more reliant on their prostheses. When prescribing, the emphasis is on function to enable the patient to have as much independence as possible. With more distal levels of amputation, the patient frequently elects to use a prosthesis on one residual limb, whilst leaving other exposed to offer sensory feedback.
Considerable development in prosthetics took place following the two world wars. The Artificial Limb Service was created in 1915 to treat the large number of soldiers who had lost a limb during the First World War. Initially only providing free prosthetic limbs to war pensioners, the UK amputee rehabilitation service has changed over the decades. There are now 44 NHS Prosthetic and Amputee Rehabilitation Centres providing a service, free at the point of delivery, to those with limb deficiency from all causes. In the last 4 decades or so, modern surgical techniques combined with advanced prosthetic engineering have provided improved functional outcome for patients. During and after World War II (1939e1945), newer and lighter materials like plastics and aluminium were joined to
Occupation The prosthetic rehabilitation team provides support throughout many transitions, such as starting primary school, the move to
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6 Froster UG, Baird P. Upper limb deficiencies and associated malformations: a population based study. Am J Med Genet 1992 Dec; 44(6): 767e81. 7 Yang Q, Khoury MJ, James LM, Olney RS, Paulozzi LJ, Erickson JD. The return of thalidomide: are birth defects surveillance systems ready? Am J Med Genetics 1997 Dec 19; 73(3): 251e8. 8 Pasquina PF, Bryant PR, Huang ME, Roberts TL, Nelson VS, Flood KM. Advances in amputee care. Arch Phys Med Rehabil 2006; 87(3 suppl 1): S34e43. 9 Hanley MA, Ehde DM, Jensen M, Czerniecki J, Smith DG, Robinson LR. Chronic pain associated with upper-limb loss. Am J Phys Med Rehabil 2009 Sep; 88(9): 742e51. quiz 752, 779. 10 Neuropathic pain e pharmacological management. NICE Guidelines, 2010. 11 Kuiken TA, Miller LA, Lipschutz RD, et al. Targeted reinnervation for enhanced prosthetic arm function in a woman with a proximal amputation: a case study. Lancet 2007 Feb 3; 369(9559): 371e80. 12 Ruth M Morris. Therapeutic influences on the upper-limb amputee. LMS, 2008. O&P Edge supplement. 13 Price EM, Fisher K. Additional studies of the emotional needs of amputees. J Prosthet Orthot 2005; 17: 52. 14 Price EM, Fisher K. Further study of the emotional needs of amputees. J Prosthet Orthot 2007; 19: 106.
newly updated mechanical joints and for the first time prostheses became comfortable and easier to use. With post-war research supported by the U.S. Veteran’s Administration, mechanical arms were developed whose hook end could open or close with a shrug of the shoulder.9 In United Kingdom, prosthetic service has been available at Queen Mary’s Hospital since the First World War. It has developed into an internationally recognised service offering highly specialised services for amputees.
Conclusion Amputation is often done as an emergency intervention or following reconstruction attempts. A residual limb of the correct length and shape is the best starting point in a patient’s rehabilitation and the surgeon has an important role in bringing the required surgical skill and attention to treatment at this stage. Early referral to a centre which has upper limb expertise will equip the patient, their family and clinicians with relevant information to allow good decision-making, reduce distress and optimize function. In the case of congenital deformity or absence, referral to the prosthetic rehabilitation centre for information can be made either before birth (if detected on scan) or after. Contact between the individual with an upper limb amputation or congenital absence and the prosthetic rehabilitation centre is likely to continue on a lifelong basis, although not everyone will choose to use a prosthesis. Improvements in the design of myoelectric prostheses may lead to increased ability in some tasks for upper limb amputees. Social participation is also facilitated by increased public awareness and acceptance of amputation. A
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REFERENCES 1 Nagi SZ. An epidemiology of disability among adults in the United States. Milbank Mem Fund Q 1976; 54: 439e67. 2 http://www.who.int/classifications/icf/en/. 3 Steven J, Hansen Scott L, Jones Neil F. Reconstruction of congenital differences of the hand. Advances in Pediatric Plastic Surgery Supplement. Plast Reconstr Surg July 2009; 124(suppl 1): 128ee43. 4 Stewart Watson. The principles of management of congenital anomalies of the upper limb. Arch Dis Child 2000; 83: 10e7. 5 UK National amputee statistical database (NASDAB); 2006e2007.
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National charity for children with hand or arm deficiency; offers advice and support for families and children through their website, DVD, family weekends, children’s activity holidays and publications for teachers and parents, www.reach.org.uk. National charity for children, parents and teachers working towards enabling children and schools with strategies to prevent bullying, www.kidscape.org.uk. National high profile charity and lobby group for all amputees, www.limbless-association.org. Part of the Douglas Bader Foundation, www.limbloss informationcentre.com
Acknowledgement Thank you to Dr Vera Neumann for comments on an earlier draft.
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HAND
varied grips possible e including key, pinch, large and small object grasp. If the thumb is competent, then the focus can turn to the other digits. In assessing and planning the reconstruction of a child’s hand the surgeon must always plan for the future. A young child can function well with basic hand grasp patterns. However, as they grow and become more independent they will need more refined, precise hand movements.
Congenital hand anomalies Gr ainne Bourke
Abstract Congenital upper limb anomalies affect 0.1e0.2% of all newborns. They are often isolated phenomena but can be associated with other congenital anomalies and may be the only external manifestation of a syndrome. Knowledge of the treatment options is imperative to ensure appropriate referral and counselling. The aim of surgery for a congenital hand anomaly is to improve both function and appearance. Apart from the face, the hand is the only other part of the body on regular display. Independent living is largely dependent on good bimanual hand function. For example a large proportion of activities of daily living such as washing, dressing, and feeding consist of bimanual tasks. It is only when we temporarily lose the function of one hand that the significance of this becomes apparent. However, children with congenital hand anomalies adapt very well to limitations of hand function and can often find “trick” manoeuvres to achieve essential tasks. As there is a wide variation in the types and severities of hand anomalies these cases are largely managed in specialized clinics. It is in this setting that the child and family will have access to long-term multidisciplinary care which includes input from geneticists, psychologists, therapists and children’s hand surgeons. For some children with more complex anomalies, psychological support can be as valuable as surgery to aid integration with and acceptance by their peers.
Timing There are very few congenital anomalies that require urgent surgical intervention although ring constriction syndrome with severe distal oedema and neonatal Volkmann’s ischaemic contracture may be the exceptions. However, referral to a specialized hand clinic where psychological, genetic and hand therapy input is available should be arranged as soon as possible after diagnosis. Certain conditions merit very early surgery not necessarily because of the severity of the hand anomaly but more for the benefit of performing surgery under local anaesthesia in neonates. This is possible for some with extra digits and for the release of minor acrosyndactyly (the distal joining of finger tips in ring constriction syndrome). Early surgery before the age of 1 year is recommended for the separation of syndactylized (joined) border digits including involvement of the first web space. This will prevent the problems related to differential growth of the digits and optimize hand function. In general if surgery is performed before school age the child will tend to forget any negative psychological experience and make a speedy postoperative recovery. However, if co-operation and compliance are essential for good postoperative outcome, as in tendon transfers, then it is best to wait unit the child is 6/7 years old. Apart from these examples, surgery for the correction of most congenital anomalies takes place once the following criteria are satisfied: (i) each subsequent figure should be increased, the risk of general anaesthesia is minimal or as low as possible given any other organ anomalies; (ii) a knowledge of the severity of other anomalies is apparent and they have been treated where possible; (iii) the size of the hand structures is such that surgery is possible; (iv) sufficient time has elapsed so that the benefit of splinting has had time to be effective. i.e. clasp thumb, trigger thumb, camptodactyly. In the majority of children this is between the ages of 1 and 2 years.
Keywords birth defect; congenital hand anomalies; duplication; finger abnormalities; forearm abnormalities; hand deformity; newborn; syndactyly; thumb abnormalities; toe transfer
Treatment principles Functionality and cosmesis The aim of surgery or therapy is to provide the child with the best functional and cosmetic outcome possible. As some of these children have other anomalies it is critical to look at the global function of the child, rather than at specific elements of their hand function. The best functional outcome will provide the child with normal grasp patterns for both single and bimanual tasks. In simple anomalies this can be achieved with relative ease. However in more complex and bilateral anomalies achieving an acceptable level of function for activities of daily living can be extremely challenging. The limits of function are largely dependent on the number of competent digits in the hand and their location. The presence of a stable, sensate and mobile thumb is essential for competent hand function. The thumb plays a key role in achieving the
Psychology The attitude of the child’s parents affects their long-term outcome. Their approach and method of coping with their child’s hand anomaly will significantly affect how the child adapts psychologically. This in turn will influence how the child integrates into society. As the severity of the congenital abnormality may vary, so too can the reaction of the child’s parents and does not necessarily parallel the severity of the child’s hand anomaly.1 Parents often have difficulty making decisions about surgery on behalf of their new baby. This can lead to parental disharmony and feelings of guilt.
Grainne Bourke MB Bch BAO FRCSI FRCS(PLAST) Consultant Plastic, Reconstructive and Hand Surgeon, Leeds Teaching Hospitals Trust, United Kingdom. Conflicts of interest: none.
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Early input from a psychologist with experience dealing with parents and children with hand anomalies can be very valuable in helping to allay fears and to encourage acceptance and support.2,3
Each category is then divided into subcategories for example group I failure of formation is divided into the subcategories: (Ia) longitudinal, (Ib) transverse or (Ic) failure of finger ray induction including cleft hand. Each subcategory is then further catalogued by the anatomical level of the deformity i.e. shoulder, arm, elbow, wrist etc. Following this the anomalies are then listed by common diagnosis for example, cleft hand, cutaneous syndactyly (Table 1).
Associated anomalies Congenital hand anomalies can be part of a recognized genetic syndrome or they may occur as a consequence of arrest or disruption in gestational development. The limb bud develops between the 4th and 8th week of gestation. At this time other organs and systems are also developing so there can be disruption of both limb and other organs simultaneously. This explains why radial ray deficiencies can be associated with other anomalies of cardiac, skeletal and gastrointestinal systems as occurs in the VACTERL sequence (Vertebral, Anal, Cardiac, Tracheooesophageal, Renal and Limb). Simultaneous proximal and distal disruptions of limb development may also occur as in Poland’s syndrome where there can be associated anomalies of the hand with symbrachydactyly and complete or partial absence of the pectoral muscles. Knowledge of the common syndromes and typically associated anomalies is very useful when assessing a child with a congenital hand anomaly. It can help in planning timing of surgery and ensuring appropriate specialist referral if other anomalies are diagnosed. In some syndromes the limb anomaly may be the only external manifestation of the syndrome. This is the case in Thrombocytopenia Absent Radius syndrome and Fanconi ’s Anaemia. The latter is a potentially fatal condition where the radial ray deficiency or duplication may be the only external feature of the syndrome. Children with Fanconi’s Anaemia usually develop bone marrow failure within the first decade of life and are at high risk of solid organ malignancy. Early diagnosis of Fanconi’s anaemia at the time of presentation of the limb anomaly is essential to ensure appropriate referral to haematology and genetic clinics for assessment and counselling.
Failure of formation Radial longitudinal deficiency: deficiencies on the radial border of the hand and arm are not common. They are significant not only because of the impairment of hand function but also because there is a high risk of associated anomalies. The risk of associated thumb hypoplasia is proportional to the severity of the radial deformity.7 Radial border anomalies have a high incidence
Abbreviated IFFSH Swanson’s classification of congenital hand anomalies Main category I. Failure of formation
Subcategory a. Transverse b. Longitudinal
c. Central II. Failure of differentiation
a. Soft tissue
b. Skeletal
Classification In 1968 Swanson first classified congenital anomalies by their morphology assuming these were related to defects in embryogenesis.4 This system has remained as the most commonly used classification system to date. It has been amended and updated with the progress of time and knowledge by Swanson, the International Federation of Societies for Surgery of the Hand (IFSSH) and the Japanese Society for Surgery of the Hand (JSSH).5,6 However there are still controversies about the classification of certain anomalies such as symbrachydactyly which was originally classified in group V as undergrowth while atypical cleft hand was classified in group I failure of formation. As the spectrum of congenital anomalies is so great there is, as one would expect, a group of unclassifiable anomalies which was added at the time of the JSSH modification to include all those anomalies which do not fit into another category. As further knowledge about the embryological aetiology of various congenital hand anomalies unfolds a new classification system based on embrynogenesis may supersede this current system. The Swanson classification system divides the anomalies into the following categories: Failure of formation, Failure of differentiation, Duplication, Overgrowth, Undergrowth, Constriction band syndrome and Generalized Skeletal Abnormalities.
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c. Tumorous
Diagnosis Longitudinal radial deficiency Longitudinal ulnar deficiency Cleft hand Cutaneous syndactyly Camptodactyly Congenital trigger digit Radioulnar synostosis Synostosis of the metacarpals Synostosis of the phalanges Symphalangia Clinodactyly Haemangioma Malformation Osteochondromatosis Enchrondroma Fibrous dysplasia Epiphyseal abnormalities
III. Duplication
Thumb duplication Ulnar polydactyly
IV. Overgrowth
Hemihypertrophy Macrodactyly
V. Undergrowth
Brachdactyly Brachysyndactyly
VI. Constriction Band Syndrome
Constriction band with oedema Constriction band without oedema
VII. Generalized abnormalities and syndromes
Marfan’s syndrome
Table 1
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of other associated congenital anomalies.8Up to 70% of children with radial longitudinal deficiency will have other medical or musculoskeletal anomalies while one third of those with thumb hypoplasia will have associated anomalies.8 These include cardiac (HolteOram syndrome), haematological (Thrombocytopenia Absent Radii, Fanconi’s Anaemia), osseous, renal and other anomalies. As the radial deformity may be the only external feature of some of these syndromes it is crucial that these children are all seen by a paediatrician and geneticist. A radiological classification of radial longitudinal deficiency was first described by Bayne and Klug in 1987.9 Type 1 has a small radius with both proximal and distal epiphyses present, type 2 has a hypoplastic radius, in type 3 the distal radius is absent and in type 4 the complete radius is absent. Later a type 0 was added where the radial carpal bones are hypoplastic and the thumb is absent but the radius is of normal length. Although the classification is based on the appearance of the bone, the tendons, neurovascular structures joint capsule and ligaments are also involved. In general the radial wrist extensors and flexors are invariably involved. The radial nerve and artery are often absent especially in the severe forms (Figure 1). In general it is better both cosmetically and functionally to correct the deviated wrist with a combination of distraction techniques followed by centralization or radicalization of the carpus over the distal ulna. This must be combined with soft tissue procedures to allow skin cover and tendon rebalancing. Once the wrist has been corrected then associated thumb hypoplasia can then be addressed with either augmentation procedures or pollicization.
However there are occasions when it is actually preferable not to correct the deformity. These include those patients with absent or limited elbow flexion. In these patients straightening the wrist may leave the hand further from the mouth or perineum and so disrupt function. In older patients who have already developed patterns of use on the ulnar border of the hand changing the hand pattern may decrease function. In those with severe soft tissue contracture the neurovascular structures will limit complete correction. In those patients with minor anomalies where there is no limitation of function surgery does not add any advantage.9 Thumb hypoplasia: disorders of the thumb limit function more than those of the other digits. The thumb plays a crucial role in hand function and enables all forms of grip apart from palmer grasp. The classification system routinely used for thumb hypoplasia is that described by Blauth in 196710 (Table 2). Thumb hypoplasia can be an isolated unilateral deformity, bilateral and may be associated with other anomalies of the musculoskeletal system or of other organs8 (Figure 2). It is thus important to ensure that other pathologies have been sought and the child has been seen by a paediatrician. In some children with Fanconi’s Anaemia or other rare disorders, the thumb anomaly may be the only external feature of the condition and so these children should be referred to a geneticist for screening at an early age. The aim of treatment of thumb hypoplasia is to improve function. As the thumb functions well in type 1 hypoplasia surgery is not indicated. For type 2 deformities surgery must address the tight first web space, the instability of the metacarpophalangeal joint with collateral ligament reconstruction and the lack of thumb opposition. The web space tightening is usually corrected using a local flap. This can be a transposition flap from the radial border of the index finger, a rotational advancement flap from the back of the hand or multiple Z plasties. Multiple opponensplasty procedures have been described but probably the most popular for congenital thumb hypoplasia is the Huber transfer, using the abductor digiti minimi.11 Type 3 thumb hypoplasia is subdivided into two groups depending on the competency of the basal joint. Where a competent basal joint is present the treatment is similar to type
Blauth’s classification of hypoplastic thumb
Figure 1 Longitudinal radial deficiency with thumb aplasia. The wrist is flexed radially due to the lack of structures on the radial side of the forearm and hand.
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Subtype Type 1
Clinical findings Small thumb but functions normally
Type 2
Small thumb Adduction contracture of the first web space Absence of thenar muscle Ulnar collateral ligament laxity at the metacarpophalangeal joint
Type 3
Small thumb Lack of intrinsics muscles Lack of extrinsics muscles Abnormal CMC joint.
Type 4
Pouce flottant
Type 5
Absent thumb
Table 2
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Central longitudinal deficiency (typical cleft hand): cleft hand or central longitudinal deficiency is a rare autosomal dominant condition. It typically involves all four limbs in a V-shaped central deformity (Figures 3 and 4). It may be associated with other anomalies of the musculoskeletal system or other organs. When associated with abnormalities such as cleft palate and ectodermal dysplasia it is called as Ectodermal, Ectrodactyly Cleft syndrome (EEC). Barsky differentiated between typical and atypical cleft hand or symbrachydactyly. The latter being a U-shaped deformity confined to one limb.16 The hand anomaly may vary from a simple soft tissue cleft to suppression of all rays except the little finger. In general it involves a combination of suppression of central rays, syndactyly and central polydactyly with the presence of transverse bones in the cleft increasing the deformity with growth. The features which cause functional limitation are involvement of the first web space which can be narrowed or even syndactylized to the index ray and a number of remaining digits.15 Despite the very unusual appearance of the hands, as long as two or more digits are preserved on each upper limb, children with typical cleft hands function well. Surgery is aimed at improving the first web space, closing the central cleft and reconstructing absent digits where possible, to improve both function and cosmesis. Several methods have been described for closure of the cleft. The most common of these is the Snow Littler procedure and that described by Miura and Komada.17 Both of these methods involve a combination of local soft tissue flaps, transposition of the index metacarpal and reconstruction of the transverse intermetacarpal ligament in order to provide an adequate first web space and close the central cleft deformity.18 Associated foot abnormalities may also need to be addressed to allow the child to wear normal footwear.
Figure 2 A hypoplastic thumb with a tight first web space.
2 deformities. Where the basal joint is not competent then pollicization of the index finger is the current treatment of choice. This is also the choice for reconstruction of type 4 and 5 thumb hypoplasia where the thumb is absent or floating. Ulnar longitudinal deficiency: this is rare. Bayne classified the radiological appearance of the ulna, radius and associated radiohumeral synostosis into four sub-types.12These range from a short ulna to severe absence with bowing of the radius and dislocation of the radial head. Radiohumeral synostosis is associated with the more severe deficiencies. This classification system was modified by Goldfarb and colleagues to include more proximal anomalies.13 Associated hand anomalies are common and have been classified by Ogino.14 When children with ulnar longitudinal deficiency first present the affected short arm is often internally rotated and thus positioned behind the child’s back. This always improves over time and eventually the arm lies in a normal plane to enable limb function. Some children have radiohumeral synostosis while others have radial head dislocation and a bowed radius. Thus each child is different and should be examined for functional limitations rather than cosmetic appearance. Treatment involves the early application of splints to correct the ulnar deviation of the wrist combined with stretching exercises. It is not usually necessary to excise the fibrous anlage of the distal ulna. In the hand, any digit may be involved and the ulnar digits may be absent. The thumb may lie in the same plane as the fingers and there may be syndactyly between any of the digits which must be corrected to improve function. Overall, children with ulnar deficiency function well. Apart from surgery to correct the associated hand anomalies they often escape surgical intervention.15
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Figure 3 A typical cleft hand illustrating a central cleft combined with a narrow first web space.
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Figure 5 Symbrachydactyly-short finger type. The first web space is also tight and requires release. This child also had deficiency of the shoulder girdle muscles and thus had a diagnosis of Poland’s syndrome.
Failure of differentiation Syndactyly: meaning joined digits, is one of the commonest congenital hand anomalies (Figure 7). It occurs in 1 in every 2000e2400 births and is often bilateral.23,24 It is more common in males than females and is variable in presentation. Five different types of autosomal dominant syndactyly have been described which may or may not involve the foot.25 Syndactyly is a consequence of an absence of apoptosis in mesodermal tissue between digits during embryonic development. This has been associated with a decrease in BMP 4.23 It is classified by the length of the skin shared between the two digits into complete where the join includes the finger tips and incomplete where the join is partial only. It is also classified by the type of tissue involved. If the join only involves skin it is called simple syndactyly while if there is bony involvement it is called as complex (Figure 8). Syndactyly is associated with several syndromes. These include the multiple suture craniosynostosis syndromes such as Apert’s and Saethre Chotzen as well as Greig’s Cephalopolysyndactyly. In these syndromic cases the syndactyly tends to be complex and often complicated. Syndactylized border digits such as the thumb and the index finger are usually separated between 6 and 12 months of age.
Figure 4 A typical cleft foot in the same child. The toes are splayed which can lead to problems with footwear.
Symbrachydactyly: in the original Swanson classification system symbrachydactyly was classified in Undergrowth (V). However following the Japanese modification of the classification system it is now placed in Failure of formation (I).5 Symbrachydactyly has previously been described as atypical cleft hand. It is sporadic in nature and presents as a U-shaped deformity. It classically involves one limb. It is a combination of short, joined digits which may be of variable severity. In some cases only rudimentary digits called as nubbins remain. It has been classified into short finger, oligodactylic, monodactylic and peromelic subgroups depending on the severity of the deformity and the number of digits remaining (Figures 5 and 6).19 The treatment of symbrachydactyly is based on improving both hand function and cosmesis. In the short finger type where a normal thumb is present simply separating the joined digits may suffice. However, in the other more severely affected types digit reconstruction is indicated to enable competent hand function. This can be achieved with the use of microvascular toe transfers. These transferred digits have excellent growth potential and are both mobile and sensate.20e22 Symbrachydactyly is associated with Poland’s syndrome. This syndrome presents with deficiency of skeletal and soft tissue components around the shoulder girdle and can include symbrachydactyly. Classically there is an absence of all or part of the pectoralis major muscles but this may be associated with deficiencies of the skeletal components of the chest wall. However other shoulder girdle muscles can be involved in isolation or combination. The absent pectoralis major can be reconstructed at an early age using an ipsilateral latissimus dorsi transfer. Staged breast reconstruction is then undertaken during teenage years.
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Figure 6 Symbrachydactyly-oligodactylic type with a single ulnar digit and radial nubbins.
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web space between the digits using a flap, reconstruction of the nail folds and separation of the digits while avoiding linear scars that may cause contractures26,27 (Figures 8 and 9). Camptodactyly: camptodactyly or “arched finger” was first described in 1846 by Tamplin.28 It is a flexion contracture of the proximal interphalangeal joint which can be progressive (Figure 10). It is not associated with trauma and unless there is additional joint laxity it is not associated with any abnormality of the distal interphalangeal joint. Benson and colleagues classified it into three main groups: infantile, adolescent and syndromic.29 Infantile and adolescent types are usually isolated to a single digit. This is usually the little finger. Syndromic types have multiple digit involvement and tend to have more severe deformities. The aetiology is due to an imbalance between the flexor and extensor systems of the finger. There is often but not always an anomaly of the lumbrical or flexor digitorum superficialis insertion. There is a secondary soft tissue shortage particularly of skin on the volar surface of the proximal phalanx which also needs to be addressed. It can be associated with bony and joint abnormalities such as loss of the normal curve of the head of the proximal phalanx. The treatment for infantile and adolescent types is quite similar. Many of patients in these groups respond well to a combination of dynamic and static splints. The aim of this treatment is to try to address the imbalance between the flexor and extensor tendons. In those who are symptomatic and do not improve with splints, surgery is an option.
Figure 7 Simple, complete syndactyly.
This is to promote the normal development of hand grasp from palmar to pincer grip and prevent deformity due to unequal digit length and growth. The separation of central rays is less essential to hand function but does improve the span of hand grasp and cosmesis. This is usually performed between the age of 1 and 2 years. Various techniques for syndactyly release have been described. The essential components are creation of an adequate and aesthetic
Figure 8 Complex syndactyly with sparing of the first web space. The differential growth of the central rays is visible when compared to the little finger.
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Figure 9 The same patient postoperatively. All four fingers have been separated using a combination of local flaps and full thickness skin grafts.
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Shortage of skin is corrected with either a local transposition flap from the border of the digit or a full thickness skin graft. Any abnormal or tight fascial bands can be divided. The abnormal anatomical insertions of the lumbrical or flexor digitorum superficialis tendons can be corrected. Several techniques have been described involving transfer of the flexor digitorum superficialis to the extensor, transfer of extensor indicis to the lumbrical insertion or lengthening or dividing the FDS tendon.30e32 In cases where there is an abnormality of the head of the proximal phalanx correction by soft tissue procedures is unlikely to yield a satisfactory outcome. In these cases a closing wedge osteotomy of the proximal phalanx or arthrodesis may be indicated.
and closing wedge. The latter should be avoided as it will further shorten the middle phalanx.32 Clinodactyly is often associated with other congenital anomalies and syndromes including Down syndrome, Apert’s syndrome, Treacher Collins syndrome and Kleinfelter’s syndrome. It can affect any digit but the little finger and thumb are the most commonly involved. In Apert’s syndrome the thumb and/or index finger are/is usually affected and require surgical correction to improve function. An opening wedge osteotomy combined with a local skin flap to correct the soft tissue deficiency works well.35 Clinodactyly also occurs in some triphalangeal thumbs. This should be suspected in a thumb which is long and has an ulnar curvature. The extra triangular phalanx may not be obvious on early X-rays but will be seen once the bone ossifies. If these are diagnosed early and the extra phalanx is small it can be removed and the thumb realigned to give and excellent result.36
Clinodactyly: means “bent finger”. It describes a curvature of the digit in the radioulnar plane (Figure 11). Familial clinodactyly is an autosomal dominant condition. It is usually bilateral and classically affects the little finger. The middle phalanx has an abnormal ‘c’ shaped epiphysis and is trapezoidal due to the deficiency in longitudinal growth. This results in a radial curvature of the digit.33 Familial clinodactyly cannot be treated with splints and surgery is usually for cosmetic rather then functional reasons. Vickers described resection of the central portion of the ‘c’ shaped epiphysis and placement of a fat graft into the defect. These cases were not splinted and showed gradual correction of the deformity over time.34 Other methods of correction that have been described are osteotomies- opening wedge, reverse wedge
Duplication Ulnar polydactyly: polydactyly is the most common congenital anomaly of the hand. It can be preaxial (radial), postaxial (ulnar) or central. Ulnar polydactyly is more common in those of African origin. It is more common in males than in females and is an autosomally dominant inherited condition. Ulnar polydactyly is usually bilateral but may affect all four limbs. The extra digit may either be a pedunculated digit (type 1b) or else a fully formed finger that articulates with the 5th metacarpal (type 1a).37 Ulnar polydactyly does not usually cause any functional problems but the extra digit is frequently removed for cosmetic reasons. If the digit is pedunculated there is a risk of the pedicle twisting and infarcting the digit causing pain. Simple ulnar polydactyly with a pedunculated digit can be excised under local anaesthetic in the neonatal period (Figure 12). If the metacarpophalangeal joint is involved, the ulnar collateral ligament must be reconstructed, the metacarpal
Figure 10 Camptodactyly of the little finger with compensatory hyperextension of the MCP joint.
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Figure 11 Clinodactyly of the little finger.
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head narrowed and the tendons assessed and realigned at the time of surgery.
Wassell’s classification of thumb duplication
Radial polydactyly: thumb duplication was categorized based on the radiological appearance into six groups by Wassel in 196938(Table 3). In 1978 Wood extended the classification to include triphalangeal thumb duplication39 (Table 3). It occurs more frequently in Caucasians and is usually an isolated abnormality (Figures 13e15). However, it can be associated with other congenital abnormalities and syndromes including Fanconi’s Anaemia, VACTERL syndrome and Duane radial ray syndrome. The principles of treatment for thumb polydactyly are to fashion a thumb of adequate length, stability and motion so that it works well and is similar in appearance to the contralateral normal thumb. Where the duplicates are of unequal size and one is superior in size and function then the smaller is removed making sure to realign the shared joint and reconstruct the collateral ligament. This may also necessitate osteotomies of the metacarpal or phalanx. If both duplicates are equal then a sharing procedure such as described by Bilhauth Cloquet may be required.40,41 It is best to avoid a nail bed scar where possible as this often causes a ridge or a split nail and can be difficult to treat.
Type 1 2 3 4 5 6 7 Table 3
It can be associated with neurofibromatosis, Ollier’s disease and Maffucci’s syndrome. The later two are syndromes involving multiple encondromatosis. Lipofibromatosis is usually unilateral and more common in males than females. The overgrowth follows the distribution of a nerve i.e. median nerve and can involve adjacent digits and extend into the palm of the hand. The affected digits are often divergent. There are two growth patterns either static or progressive. Static macrodactyly is present at birth and the digit grows proportionally with the child. Progressive macrodactyly is also present at birth but the digit grows disproportionally when compared with the rest of the hand. This type of macrodactyly will require more aggressive and earlier treatment.43 The psychological implications of macrodactyly are significant. Both parents and child are usually more concerned about the abnormal size and appearance of the macrodactylous digit than any limitation of function. Early surgical intervention is aimed at debulking soft tissues but preserving vital structures such as nerves and arteries. It is important to inform both parent and child that multiple staged procedures will be necessary to achieve an acceptable outcome. Access incision should be placed in a midlateral plane where possible to avoid obvious scars, prevent contractures and promote motion. Limitation of bone growth can be achieved with epiphyseal arrest. This is performed when the digit is the same radiological length as that of the same sex parent. Differential arrest of the epiphysis can be performed to correct the abnormal curvature that occurs when adjacent involved digits are divergent. Osteotomies
Overgrowth Macrodactyly: is probably one of the most difficult congenital hand anomalies to treat. It was classified by Flatt into four groups based on its aetiology. These are gigantism with lipofibromatosis, gigantism with neurofibromatosis, gigantism with digital hyperostosis and gigantism with hemihypertrophy.42
Figure 13 In correcting thumb duplication, nail bed scars should be kept to a minimum as there is a high risk of split or ridged nail deformities.
Figure 12 Ulnar polydactyly type 1b.
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Radiological findings Bifid distal phalanx Duplication of distal phalanx Bifid proximal phalanx Duplication of proximal phalanx Bifid metacarpal Duplication of metacarpal Duplication triphalangeal thumb
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Figure 15 Proximal thumb duplication. Here as the ulnar digit was smaller and less functional it was excised.
Figure 14 Where there are two unequal components the smaller is sacrificed. It is essential to reconstruct the collateral ligament during the procedure.
The treatment is surgical with excision of the constricting band and z plasty closure, release of the acrosyndactyly and where necessary digit reconstruction. It is important to realize that anatomical structures proximal to the constricting band are normal. Thus free microvascular toe transfer is an effective means of digit reconstruction in cases of complete digit loss. However, the involvement of multiple limbs often interferes with available donor toes (Figure 16e18). In general, despite the loss of distal digital parts children with ring constriction syndrome have good hand function. Often simply releasing conjoined digits and correcting deep constrictions will yield a very functional result.
can be performed to correct abnormalities of width, length and curvature. If a single digit is involved it is worth considering ray amputation and in the case of the thumb, reconstruction with a microvascular toe transfer.43 Ring constriction syndrome: also called amniotic band syndrome, it has an incidence of 1 in 1,200e1 in 15,000.44 It occurs equally in males and females and usually involves more than one limb. It involves a combination of distal ring constriction, intrauterine digit amputation and acrosyndactyly. There is distal syndactyly with proximal fenestrations.44There are two theories describing its aetiology e intrinsic and extrinsic. The intrinsic theory attributing the deformities to an abnormality in the development of the subcutaneous tissues was first described by Streeter in 1930 and subsequently modified by Patterson in 1961.26,45 The extrinsic theory describes a rupture of the amniotic membrane with the limb or body part then lying between the amniotic and chorionic membranes. This was described by Torpin in 1965.46 It is associated with other anomalies such as club foot, cleft lip and palate, craniofacial anomalies and limb length discrepancies. The hand anomalies vary considerably, but if the constricting band is tight it can result in abnormalities of nerve and vessels as well as skin and subcutaneous fat. If there is severe oedema distal to the ring constriction then urgent surgery is indicated to avoid further compromise of lymphatic and venous flow in the limb.
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Generalized skeletal abnormalities Trigger thumb: is a common condition seen in young children. Whether it is actually a congenital anomaly is often debated. Several studies have illustrated its absence at birth.47,48 Notta first described the swelling of the flexor pollicis longus at the level of the A1 pulley in 1850.49 This description has remained and the swelling is now classically called Notta’s node. This palpable swelling combined with a thickened A1 pulley causes the triggering. However once the pulley has been released the tendon reverts to normal and the node disappears. The child usually presents with a thumb flexed at the interphalangeal joint rather than with triggering as this is too painful. Children presenting before the age of one can be treated conservatively. One third of those presenting before the age of 6 months resolve spontaneously and 12% of those presenting between the ages of 6e12 months also resolve without intervention.50 Children
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Figure 18 Foot involvement in ring constriction syndrome demonstrating the band encircling the great and second toes. Figure 16 Ring constriction syndrome illustrating the tight constricting rings and distal oedema.
thumbs with aplasia of the extensor pollicis brevis and a tight web space. These usually correct with the use of splints, Type 2 are complex thumbs with associated abnormalities of the MCP joint, collateral ligament instability, hypoplasia of the thenar muscles and collateral ligament instability. Type 3 clasped thumbs are associated with syndromes such as arthrogryposis and windblown hand anomalies.51 The treatment for all types is with splints initially. These help to release the web space contracture and hold the thumb in an abducted and extended position. A significant number of type 1 thumbs will correct with splint therapy alone. In those cases with
who present after the age of 3 years are at risk of developing a flexion contracture at the interphalangeal joint and thus should be managed with an A1 pulley release. The surgery is performed through a transverse incision at the level of the metacarpophalangeal joint with preservation of the adjacent digital bundles. The A1 pulley is released in full and the tendon motion should be checked before the skin is sutured. Once the pulley has been fully released the symptoms resolve and seldom recur. Clasp thumb: congenital clasped thumb involves flexion of the thumb at the metacarpo-phalangeal (MCP) joint with an adduction contracture of the first web space (Figure 19). The thumb is flexed across the palm. The interphalangeal joint may be involved also if the extensor pollicis longus is absent or hypoplastic. It must be differentiated from congenital trigger thumb where only the interphalangeal joint is involved. It may be an isolated anomaly but more commonly is part of a syndrome such as, windblown hand, Freeman Sheldon syndrome, arthrogryposis or other neuromuscular syndromes.49 The deformity is present at birth but children present after 3/4 months. They are classified into three main groups: types 1/supple
Figure 17 The same patient (as shown in Figure 16 with ring constriction syndrome) 6 weeks after digit reconstruction with synchronous bilateral second toe transfers.
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Figure 19 A clasped thumb with a tight first web space, flexion of the metacarpophalangeal joint and flexion of the interphalangeal joint. The thumb is positioned across the palm.
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15 Manske PR, Goldfarb CA. Congenital failure of formation of the upper limb. Hand Clin 2009 May; 25: 157e70. 16 Barsky AJ. Cleft hand: classification, incidence, and treatment. Review of the literature and report of nineteen cases. J Bone Joint Surg 1964 Dec; 46: 1707e20. 17 Buck-Gramcko D. Cleft hands: classification and treatment. Hand Clin 1985 Aug; 1: 467e73. 18 Sykes P, Kay S. The cleft hand. In: Gupta A, Kay S, Scheker L, eds. The growing hand. 1st edn. Mosby, 2000. 19 Buchler U. Symbrachydactyly. In: Gupta A, Kay S, Scheker L, eds. The growing hand. 1st edn. Mosby, 2000. 20 Kay SP, Wiberg M. Toe to hand transfer in children. Part 1: technical aspects. J Hand Surg Br 1996 Dec; 21: 723e34. 21 Kay SP, Wiberg M, Bellew M, Webb F. Toe to hand transfer in children. Part 2: functional and psychological aspects. J Hand Surg Br 1996 Dec; 21: 735e45. 22 Kay SP. Microvascular toe transfer in children. In: Gupta A, Kay S, Scheker L, eds. The growing hand. Mosby, 2000. 23 Tonkin MA. Failure of differentiation part I: syndactyly. Hand Clin 2009 May; 25: 171e93. 24 Smith P. Syndactyly. In: Gupta A, Kay S, Scheker L, eds. The growing hand. 1st edn. Mosby, 2000. 25 Temtamy SA, McKusick VA. The genetics of hand malformations. Birth Defects Orig Artic Ser 1978; 14. iexviii, 1e619. 26 Buck-Gramcko D. Syndactyly between the thumb and index finger. In: Buck-Gramcko D, ed. Congenital malformations of the hand and forearm. Churchill Livingstone, 1997. 27 Ger E. Syndactyly. In: Buck-Gramcko D, ed. Congenital malformations of the hand and forearm. Churchill Livingstone, 2000. 28 Burke FD. Camptodactyly. In: Gupta A, Kay S, Scheker L, eds. The growing hand. Mosby, 2000. 29 Benson LS, Waters PM, Kamil NI, Simmons BP, Upton 3rd J. Camptodactyly: classification and results of nonoperative treatment. J Pediatr Orthop 1994 NoveDec; 14: 814e9. 30 McFarlane RM, Classen DA, Porte AM, Botz JS. The anatomy and treatment of camptodactyly of the small finger. J Hand Surg Am 1992 Jan; 17: 35e44. 31 Gupta A, Burke FD. Correction of camptodactyly. Preliminary results of extensor indicis transfer. J Hand Surg Br 1990 May; 15: 168e70. 32 Ty JM, James MA. Failure of differentiation: Part II (arthrogryposis, camptodactyly, clinodactyly, madelung deformity, trigger finger, and trigger thumb). Hand Clin 2009 May; 25: 195e213. 33 Burke FD. Clinodactyly. In: Gupta A, Kay S, Scheker L, eds. The growing hand. Mosby, 2000. 34 Vickers D. Clinodactyly of the little finger: a simple operative technique for reversal of the growth abnormality. J Hand Surg Br 1987 Oct; 12: 335e42. 35 Fereshetian S, Upton J. The anatomy and management of the thumb in Apert syndrome. Clin Plast Surg 1991 Apr; 18: 365e80. 36 Upton J, Shoen S. Triphalangeal thumb. In: Gupta A, Kay S, Scheker L, eds. The growing hand. Mosby, 2000. 37 Galjaard RJ, Smits AP, Tuerlings JH, et al. A new locus for postaxial polydactyly type A/B on chromosome 7q21eq34. Eur J Hum Genet 2003 May; 11: 409e15. 38 Wassel HD. The results of surgery for polydactyly of the thumb. Clin Orthop Relat Res 1969 MayeJun; 64: 175e93. 39 Wood VE. Polydactyly and the triphalangeal thumb. J Hand Surg Am 1978 Sep; 3: 436e44. 40 Ikuta Y. Thumb duplication. In: Buck-Gramcko D, ed. Congenital malformations of the hand and forearm. Churchill Livingstone, 2000.
a supple deformity that has not corrected with splints as well as types 2 and 3, surgery aims to release the web space contracture with the use of local flaps, reconstruct the extensor mechanism and correct any deformity of the metacarpophalangeal joint.
Summary Congenital hand anomalies are common and can be associated with other anomalies.52 It is important to have an awareness of treatment principles so that parents receive the appropriate counselling and children are referred to specialist clinics if warranted. The Swanson classification system is widely accepted and helps with both communication and documentation of anomalies. The types of anomalies are very diverse and it is not possible to produce a comprehensive and complete algorithm of treatment options in this article. However, the principles of management, including the important role played by skilled therapists and psychologists are demonstrated. A
REFERENCES 1 Bradbury ET, Hewison J. Early parental adjustment to visible congenital disfigurement. Child Care Health Dev 1994 JuleAug; 20: 251e66. 2 Bradbury ET, Kay SP, Hewison J. The psychological impact of microvascular free toe transfer for children and their parents. J Hand Surg Br 1994 Dec; 19: 689e95. 3 Bellew M, Kay SP. Psychological aspects of toe to hand transfer in children. Comparison of views of children and their parents. J Hand Surg Br 1999 Dec; 24: 712e8. 4 Swanson AB, Barsky AJ, Entin MA. Classification of limb malformations on the basis of embryological failures. Surg Clin North Am 1968 Oct; 48: 1169e79. 5 De Smet L. Classification for congenital anomalies of the hand: the IFSSH classification and the JSSH modification. Genet Couns 2002; 13: 331e8. 6 Swanson AB. A classification for congenital limb malformations. J Hand Surg Am 1976 Jul; 1: 8e22. 7 James MA, Green HD, McCarroll Jr HR, Manske PR. The association of radial deficiency with thumb hypoplasia. J Bone Joint Surg 2004 Oct; 86-A: 2196e205. 8 Goldfarb CA, Wall L, Manske PR. Radial longitudinal deficiency: the incidence of associated medical and musculoskeletal conditions. J Hand Surg Am 2006 Sep; 31: 1176e82. 9 Bayne LG, Klug MS. Long-term review of the surgical treatment of radial deficiencies. J Hand Surg Am 1987 Mar; 12: 169e79. 10 Blauth W. [The hypoplastic thumb]. Arch Orthop Unfallchir 1967; 62: 225e46. 11 de Roode CP, James MA, McCarroll Jr HR. Abductor digiti minimi opponensplasty: technique, modifications, and measurement of opposition. Tech Hand Up Extrem Surg 2008 Mar; 14: 51e3. 12 Bayne LG. Ulnar club hand (Ulnar deficiencies). In: Green DP, ed. Operative hand surgery. 1st edn. New York: Churchill Livingstone, 1982: 245e57. 13 Goldfarb CA, Manske PR, Busa R, Mills J, Carter P, Ezaki M. Upperextremity phocomelia reexamined: a longitudinal dysplasia. J Bone Joint Surg 2005 Dec; 87: 2639e48. 14 Ogino T, Kato H. Clinical and experimental studies on ulnar ray deficiency. Handchir Mikrochir Plast Chir 1988 Nov; 20: 330e7.
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41 Teoh L. Polydactyly. In: Gupta A, Kay S, Scheker L, eds. The growing hand. Mosby, 2000. 42 Brotherston MM-B, Kleinert H. Macrodactyly. In: Gupta A, Kay S, Scheker L, eds. The growing hand. Mosby, 2000. 43 Carty MJ, Taghinia A, Upton J. Overgrowth conditions: a diagnostic and therapeutic conundrum. Hand Clin 2009 May; 25: 229e45. 44 Kawamura K, Chung KC. Constriction band syndrome. Hand Clin 2009 May; 25: 257e64. 45 Patterson TJ. Congenital ring-constrictions. Br J Plast Surg 1961 Apr; 14: 1e31. 46 Torpin R. Amniochorionic mesoblastic fibrous strings and amniotic bands: associated constricting fetal malformations or fetal death. Am J Obstet Gynecol 1965 Jan 1; 91: 65e75.
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47 Ogino T. Trigger thumb in children: current recommendations for treatment. J Hand Surg Am 2008 JuleAug; 33: 982e4. 48 Rodgers WB, Waters PM. Incidence of trigger digits in newborns. J Hand Surg Am 1994 May; 19: 364e8. 49 Watt AJ, Chung KC. Generalized skeletal abnormalities. Hand Clin 2009 May; 25: 265e76. 50 Dinham JM, Meggitt BF. Trigger thumbs in children. A review of the natural history and indications for treatment in 105 patients. J Bone Joint Surg Br 1974 Feb; 56: 153e5. 51 Mih AD. Congenital clasped thumb. Hand Clin 1998 Feb; 14: 77e84. 52 McCarroll HR. Congenital anomalies: a 25-year overview. J Hand Surg Am 2000 Nov; 25: 1007e37.
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CME SECTION
CME questions based on the Mini-Symposium on “Imaging” The following series of questions are based on the MiniSymposium on “Imaging”. Please read the articles in the Mini-Symposium carefully and then complete the selfassessment questionnaire by filling in the square corresponding to your response to each multiple-choice question. After completing the questionnaire, either post or fax the answer page to the Orthopaedics and Trauma Editorial Office at the address at the bottom of the RESPONSE sheet. Please photocopy this page if you wish to keep your copy of Orthopaedics and Trauma. Replies received before the next issue of the journal is published will be marked and those reaching an adequate standard will qualify for three external CME points. You will be notified of your marks and a CME certificate will be despatched, via email, for your records.
C The skeletal survey involves about the same dose of radiation as the CT D The skeletal survey involves about three times as much radiation as the CT E The skeletal survey involves about ten times as much radiation as the CT 4 After what interval should a skeletal survey be repeated in cases of suspected non-accidental injury? A 2 days B 7 days C 11e14 days D 21e28 days E When indicated for routine follow-up of fractures found on the first survey
Questions
5 What proportion of children with rib fractures sustain them through any cause other than non-accidental injury? A 10% B 30% C 50% D 70% E 90%
1 When carrying out a trauma CTwith contrast, how does the protocol differ for the haemodynamically unstable patient compared to the haemodynamically stable patient? A The unstable patient should not be scanned B The unstable patient has a limited scan of the chest in the arterial phase and pelvis in the portal venous phase C The unstable patient has a scan without contrast, as it is unreliable in hypotension D The unstable patient has a scan of the chest in the arterial phase then the torso in the portal venous phase E The unstable patient has a scan of the chest and the torso in the arterial phase, followed by a further scan of the torso in the portal venous phase
6 What is the source and fate of Technetium 99m, used in bone scans? A Formed by decay of Technetium 100m, emits beta particles with half life of 2 days B Formed by decay of Molybdenum 99, emits beta particles with half life of 24 h C Formed by decay of Technetium 101, emits gamma particles with half life of 6 h D Formed by decay of Molybdenum 99, emits gamma particles with half life of 6 h E Formed in cyclotron by bombardment of Lithium, emits gamma particle with half life of 12 h
2 In suspected non-accidental injury of an 18-month-old, what films are taken when a skeletal survey is requested? A A babygram e single plate whole-body film B Views appropriate to any clinical signs, such as bruising, tenderness or lost function C Lateral Skull, AP chest, AP pelvis and views appropriate to any clinical signs on limbs D Lateral Skull, AP chest, AP pelvis and single view of all four limbs, with orthogonal views of any abnormalities E Skull, spine, abdomen, pelvis, AP and two oblique chest views, single view of all four limbs, hands and feet
7 What proportion of otherwise occult acute fractures, not visible on X-ray, are detected by isotope bone scanning at 7 days? A 50% B 70% C 90% D 95% E 100% 8 What is the gold standard nuclear medicine technique for localizing infection? A Technetium 99m bone scan at 7 days after onset of symptoms B Indium 111 labelled leucocyte scan C Gallium 67 citrate bone scan at 7 days after onset of symptoms
3 How does the radiation dose of a skeletal survey carried out in suspected non-accidental injury compare to the radiation dose of a CT scan of the abdomen? A The skeletal survey involves about one-tenth as much radiation as the CT B The skeletal survey involves about one-third as much radiation as the CT
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CME SECTION
D Technetium 99 exametazime labelled leucocyte scan E Gallium 67 citrate leucocyte scan
B Increase the receiver bandwidth C Use spin echo rather than gradient echo sequences D Use T1 rather than T2 imaging E Use of STIR rather than chemical shift for fat suppression
9 Which of the following patients is least likely to benefit from cement augmentation kyphoplasty? A A patient with concave vertebral morphology and 2 months of symptoms B A patient with swelled front vertebral morphology with 4 months of symptoms C A patient with bow shaped vertebral morphology with 6 months of symptoms D A patient with projecting vertebral morphology and 9 months of symptoms E A patient with dented vertebral morphology and 12 months of symptoms
Please fill in your answers to the CME questionnaire above in the response section provided to the right. A return address and fax number is given below the response section.
Responses Please shade in the square for the correct answer. B C D E 1A 2A B C D E 3A B C D E 4A B C D E 5A B C D E 6A B C D E 7A B C D E 8A B C D E 9A B C D E 10 A B C D E 11 A B C D E 12 A B C D E
10 To what does ‘magic angle’ refer in MR imaging? A The angle between the static magnetic field and the gradient coils B The angle of precession of protons under the influence of an applied external strong magnetic field C The change in magnetization vector caused by the application of a pulsed external field D The angle of highly ordered collagen fibres to the external field that results in large changes to T2 relaxation time E The orientation of metal artefacts that produces destructive degradation of T1 weighted images
Your details (Print clearly) NAME ............................................................................
11 What pathology is seen in best detail by ultrashort echo time MRI? A Tendinopathy B Fracture C Metastatic infiltration D Synovitis E Infection
ADDRESS ............................................. ........ ............................................. EMAIL ................................................. ........ RETURN THE COMPLETED RESPONSE FORM by fax to þ44-113-392-3290, or by post to CME, Orthopaedics and Trauma, Academic Department of Orthopaedic Surgery, “A” Floor Clarendon Wing, Leeds General Infirmary, Great George Street, Leeds LS1 3EX, UK.
12 Which of the following does not reduce the extent of artefacts on MRI scanning in the presence of metallic orthopaedic implants? A Use of titanium rather than stainless steel implants
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CME SECTION
Answers to CME questions based on the Mini-Symposium on “Pathology” Please find below the answers to the Orthopaedics and Trauma CME questions from Vol. 24, issue 6 which were based on the Mini-Symposium on “Pathology”
Answers 1 A,
B,
C,
D-
E,
2 A,
B,
C,
D-
E,
3 A,
B,
C,
D,
E-
4 A,
B,
C-
D,
E,
5 A,
B,
C,
D,
E-
6 A,
B-
C,
D,
E,
7 A,
B,
C-
D,
E,
8 A-
B,
C,
D,
E,
9 A,
B,
C-
D,
E,
10 A ,
B-
C,
D,
E,
11 A -
B,
C,
D,
E,
12 A ,
B-
C,
D,
E,
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BOOK REVIEWS
Paediatric orthopaedics: a system of decision-making
Children’s Orthopaedics and Fractures
Benjamin Joseph, Selvadurai Nayagam, Randall T Loder, Ian Torode, 1st edn. Published by: Hodder Arnold, 2009, ISBN 978-0-34088945-9, Price: £80.00, 560 pages
Edited by Benson M, Fixsen J, Macnicol M, Parsch K, 3rd edn. Publihed by: Springer, 2010, £125, 869 pages
When this textbook first appeared 16 years ago, it made a positive impression with its comprehensive and generally wellwritten contributions from a wide range of authors from all over the world. If there was a criticism it would be that some topics were treated in a somewhat superficial manner, particularly in the section on fractures, which was relegated to the last 100 pages of the book. The latest incarnation of this book is now several hundred pages longer, and it is a weightier tome in all senses. Many sections have been strengthened and trauma is now dealt with in an appropriately detailed manner. Whilst there is rightly a greater emphasis on evidence-based management, there is nevertheless still room for the individual opinion. It has to be said that in general, the more successful chapters are those in which the mantle of authorship has been passed to younger surgeons; here you are more likely to find a more balanced account with up-to-date references. The book is a little light on basic sciences as applied both to normal growth and to remodelling following injury. Work on physeal reorientation following injury is wrongly attributed to Hueter and Volkmann when Pauwels should get the credit. There is no mention in the limb length discrepancy chapter of Menelaus’ rule of thumb for estimating remaining growth around the knee. An examination candidate who performed the Coleman block test as illustrated would need to do well elsewhere in the examination. However, these are minor carpings. In general, the layout is clear and the quality of illustration high. Orthopaedic trainees preparing for their exit examinations will find most of what they need to know here, and reading it should be a pleasure. It should also be a useful reference resource for all orthopaedic surgeons, regardless of their specialty interest. A
I read this book in much the same way that I think its target readership will e by dipping in and out and reading a chapter or two whenever there are a few minutes to spare or interest has been stimulated. This is easy to do because the 500 pages are arranged into 72 chapters so none are very long. The information is all the more digestible because the chapter layout is excellent. Basic information, with good illustrations, and treatment options in bullet form are followed by an easy to follow, but more comprehensive algorithm, to cover most circumstances. References are given but restricted to a key selection. Presentation is much enhanced by use of a third colour. The scope is enormous but not comprehensive; sections on common forefoot and hand deformities, including hallux valgus, curly toes and trigger thumb, have not been included but would have been useful for the target audience. The section on Perthes disease is particularly interesting and unusual, in that it makes no reference to either Catterall or Herring. However it is not diminished for that, as all four authors are recognized authorities on their subjects. This book is ideal for the senior trainee approaching final professional examinations such as the FRCS(Tr&Orth). It is compact enough to be carried around and referred to between cases in the children’s clinic and it’s an easy book to “cram” for the exam. I enjoyed reading this book and recommend it. A
Brian Scott MBBS FRCS FRCS(Orth) Consultant Children’s Orthopaedic Surgeon, Orthopaedic Department, Leeds General Infirmary, Great George Street, Leeds LS1 3EX, UK.
Musculoskeletal oncology: benign tumors (DVD-ROM)
J Mark H Paterson
Albert J Aboulafia, Edward Y Cheng, Medical eds. American Academy of Orthopaedic Surgeons, ISBN: 978-0-89203-585-4, $175.00
Barts and the London NHS Trust, West Smithfield, London EC1A 7BE, UK.
This DVD from the AAOS is designed for CME points for the practising Orthopaedic Surgeon. It is easy to install and user friendly. The cases are easy to work through, well described with good quality illustrations and appropriately referenced. The DVD is at an appropriate level for the trainee approaching the FRCS (Tr. & Orth.) examination. For the number of cases provided I suspect this would be better placed in a departmental library rather than an individual’s collection, unless one had an interest in musculoskeletal oncology. Once again the AAOS has delivered a high quality product.A
Robert U Ashford
Musculoskeletal Infection: AAOS Orthopaedic Knowledge Update George Cierny III, Alex McLaren, Montri Wongworawat, eds. Musculoskeletal Infection, Member: $129; Resident: $109, Price: AAOS, Published 2009, 280 pages
Bone and joint infection is important. It appears across all orthopaedic practice from trauma to joint replacement; spine surgery to paediatrics. While the trainee may not need to know every aspect of microbiology and antibiotic pharmacology, a full understanding of the pathogenesis of bone and implantrelated infection, and the principles of management are essential for all.
FRCS (Tr & Orth)
Consultant Orthopaedic Surgeon, Orthopaedic Department, University Hospitals of Leicester NHS Trust, UK.
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FRCS
Consultant Paediatric Orthopaedic Surgeon, Orthopaedic Hospital,
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BOOK REVIEWS
This book is a timely addition to the AAOS portfolio. It is written by those who have contributed much to our thinking on musculoskeletal infection, over many years. I would strongly recommend this update to all SpRs approaching the FRCS(Orth) and most Consultants. Many chapters are good but the sections on Adult Osteomyelitis, Surgical Debridement, Local Antibiotics, Biofilms and Infection Prevention are outstanding examples of authoritative summaries of current practice. The sections on specific infections (spine, hand, diabetic foot, etc) are comprehensive, in contrast to the rather shorter overviews of infection in open fractures and prosthetic joints. Procedure-related Reduction of the Risk of Infection should be required reading for all doctors who undertake any surgical procedure. It focuses the mind on the many factors which determine infection rates and puts antibiotic prophylaxis in its appropriate place. All of the sections are enhanced with annotated references, allowing the reader to select those papers which merit further study.
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As with any overview of a large topic, there are omissions. It is unfortunate that there are no sections on osteomyelitis in children, infective bursitis or external fixator pin infection which are all common clinical scenarios. This book is written primarily from a US standpoint and, as such, the antibiotic regimes tend towards cephalosporins. The UK surgeon should be aware that concerns about C. difficile have limited our use of cephalosporins. Antibiotic choice must always be a local issue. Overall, this is an excellent book which should fill a definite gap in many trainees’ knowledge. It should be in all Orthopaedic Department libraries and many personal bookcases. A
Martin McNally
MD FRCSEd FRCS(Orth)
Lead Surgeon, Bone Infection Unit, Nuffield Orthopaedic Centre, Oxford, UK.
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