MUSCULOSKELETAL ASPECTS OF CEREBRAL PALSY H. Kerr Graham, P. Selber. From the Royal Children s Hospital, Melbourne, Australia 1,3,6

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1 Review article MUSCULOSKELETAL ASPECTS OF CEREBRAL PALSY H. Kerr Graham, P. Selber From the Royal Children s Hospital, Melbourne, Australia Cerebral palsy is the most common cause of physical disability affecting children in developed countries, with an incidence of 2.0 to 2.5 per 1000 live births. 1 It is not a single entity but a heterogeneous collection of clinical syndromes, characterised by abnormal motor patterns and postures. Although in most parts of the world the orthopaedic burden secondary to poliomyelitis and myelomeningocele is declining rapidly, the prevalence of cerebral palsy is static or increasing. It is the most common diagnosis after trauma in most paediatric orthopaedic units and is therefore of enormous strategic importance in terms of allocation of resources, planning and service delivery. The definitions of cerebral palsy have undergone a number of refinements by developmental paediatricians and neurologists. They stress two features. First, cerebral palsy is the result of a lesion in the immature brain, which is nonprogressive; it is a static encephalopathy. 2 It is clearly important to differentiate cerebral palsy from progressive neurological conditions from the standpoint of both taxonomy and clinical management. Secondly, cerebral palsy results in a disorder of posture and movement which is permanent but not unchanging. 3 To this we would add a third feature, that it results in progressive musculoskeletal pathology in most affected children. 4 It is inappropriate to emphasise that the cerebral lesion is static without clearly stating that the musculoskeletal pathology will be progressive. In Little s original description 5 of spastic diplegia, prominence was given to the description of the musculoskeletal deformities. The newborn child with cerebral palsy usually has no deformities or musculoskeletal abnormalities at birth. Scoliosis, dislocation of the hip and fixed contractures develop during the rapid growth of childhood. Cerebral palsy is a H. K. Graham, MD, FRCS Ed, FRACS, Professor of Orthopaedic Surgery, University of Melbourne P. Selber, MD, Clinical Fellow Department of Orthopaedics, Royal Children s Hospital, Flemington Road, Parkville, Victoria, Australia Correspondence should be sent to Professor Graham British Editorial Society of Bone and Joint Surgery doi / x.85b $2.00 J Bone Joint Surg [Br] 2003;85-B: useful term which describes a large group of children with motor impairment from many causes and expressed as a wide variety of clinical syndromes. The preferred term is therefore the cerebral palsies. 6 It was formerly considered that most cases of cerebral palsy were the result of obstetric misadventure. Careful epidemiological and brain-imaging studies suggest that it frequently has antenatal antecedents and is often multifactorial. Recent studies also point to an increasing number of specific aetiological factors including intrauterine infections and inherited malformations. 1 These investigations will in time lead to both primary prevention and secondary minimisation of cerebral injury. The increase in the incidence of cerebral palsy in preterm infants is because of neonatal intensive care and a rise in multiple births. The rates of cerebral palsy in babies born at term are steady, despite strategies to reduce birth asphyxia. The most important issue in cerebral palsy is the elucidation of the causal pathways from population-based epidemiological studies. This will lead to primary prevention, which in a chronic, incurable condition is clearly the most humane and cost-effective strategy. Cerebral palsy is subdivided according to the movement disorder and its topographical distribution. Spastic and mixed motor disorders account for more than 85% of children on current registers; dyskinetic cerebral palsy is much less common. 1,6 The most common topographical syndromes are spastic hemiplegia, spastic diplegia and spastic quadriplegia which is also known as whole-body involvement. 1,3,6 Measuring function and natural history In arthrogryposis multiplex congenita, Staheli (personal communication) stated that in the first decade the most important priority is function, in the second appearance and in the third and subsequent decades the avoidance of pain. This is equally true in the cerebral palsies. Most functional gains are made in the first decade. Gross motor function in the cerebral palsies is related to the degree of involvement, which in turn is a manifestation of the site and severity of the cerebral lesion. All children with spastic hemiplegia walk independently; most of those with spastic diplegia will walk but many require assistive devices. Those with spastic VOL. 85-B, No. 2, MARCH

2 158 H. KERR GRAHAM, P. SELBER CNS pathology PVL Loss of inhibition LMN Loss of connections to LMN (and other pathways) Positive features of UMN syndrome Spasticity Hyper-reflexia Clonus Co-contraction Neural Negative features of UMN syndrome Weakness Fatiguability Poor balance Sensory deficits Mechanical Fig. 1 Diagram showing the neuromusculoskeletal pathology in cerebral palsy. The pathology of the central nervous system in cerebral palsy is defined as a static encephalopathy. Given the infinite variability of the location and severity of the lesions the clinical syndromes are in turn extremely variable. In motor terms, cerebral palsy results in an upper motor neurone lesion which in this diagram is considered to have a series of positive and negative features that interact to produce the familiar musculoskeletal pathology. Historically, clinicians have concentrated on the positive features and the negative features have been relatively ignored. It is probable that the optimum management of children with cerebral palsy will require integrated management of both the positive features and the negative features. Musculoskeletal pathology Muscle shortening Bony torsion Joint instability Degenerative arthritis quadriplegia rarely have functional walking. Motor function can be reliably measured using the gross motor function measure and classified using the gross motor functional classification system. 7,8 In a recent study Rosenbaum et al 9 described motor development in the cerebral palsies as a series of curves of motor development. These aid our understanding of gross motor development in children with cerebral palsy of all degrees of severity. They are an excellent guide to prognosis and have significant implications in the understanding of the potential and limitations of management strategies. Neuromusculoskeletal pathology in the cerebral palsies The progressive nature and effects on the neuromusculoskeletal pathology have been understood with the help of a number of animal models as well as clinical studies. The key feature of the musculoskeletal pathology is a failure of longitudinal growth of skeletal muscle (Fig. 1). An apt, orthopaedic synonym for cerebral palsy is short muscle disease. 3 The conditions for normal muscle growth are regular stretching of relaxed muscle under conditions of physiological loading. In children with cerebral palsy, the skeletal muscle does not relax during activity because of spasticity and these children have greatly reduced levels of activity because of weakness and poor balance. Ziv et al 10 demonstrated the imbalance between the growth of long bones and muscle-tendon units in an animal model, the hereditary spastic mouse. Affected juveniles develop contractures of the gastrocnemius and equinus deformity because of a failure of longitudinal muscle growth. Cosgrove and Graham 11 confirmed the role of spasticity in the genesis of contractures in the hereditary spastic mouse by showing that muscle growth can be enhanced by the injection of botulinum toxin A (BTX-A) soon after birth. The musculoskeletal pathology is much more complex and damaging than simply the development of contractures. THE JOURNAL OF BONE AND JOINT SURGERY

3 MUSCULOSKELETAL ASPECTS OF CEREBRAL PALSY 159 Torsion of long bones, joint instability and premature degenerative changes in weight-bearing joints are common and debilitating 3,12,13, and young adults with cerebral palsy commonly experience pain from early degenerative joint disease. 14 The primary aim in the management of spasticity is to prevent the development of fixed contractures. If they occur, correction of fixed musculoskeletal deformities is required before the onset of decompensation. Once complex decompensated joint pathology has developed, the surgical options are limited, the rate of complications escalates and the outcome of salvage surgery is frequently indifferent. There are two important longitudinal studies of gait in children with spastic diplegia which confirm that the musculoskeletal pathology and the attendant gait disorder are progressive during childhood. 15,16 They provide an important insight into the natural history of the process and act as a framework for the interpretation of the results of surgical intervention. The upper motor neurone syndrome: weakness and spasticity Cerebral palsy is the most common cause of the upper motor neurone syndrome (UMN) in childhood (Fig. 1) which is characterised by positive features such as spasticity, hyper-reflexia and co-contraction, and negative features including weakness, loss of selective motor control, sensory deficits and poor balance. 17 Clinicians have traditionally focused more on the positive features because it is possible to treat spasticity, but it is the negative features which determine the locomotor prognosis. Weakness and loss of selective motor control determine when or if a child will walk. Deficits in balance will dictate dependence on a walking aid. The management of spasticity in the cerebral palsies The management of spasticity has become increasingly sophisticated and effective in recent years. Treatment can be classified as temporary or permanent and as focal or generalised. 17,18 Intramuscular injections are temporary and focal. The most commonly used agents are phenol and BTX-A. Phenol has a small but useful role as a neurolytic agent but can only be used for motor nerves such as the obturator nerve in the presence of adductor spasticity and the musculocutaneous nerve for spasticity of the elbow flexors. 17,19 BTX-A is a potent neurotoxin produced by the bacterium Clostridium botulinum under anaerobic conditions. It binds to cholinergic nerve endings and inhibits release of the neurotransmitter acetylcholine by blocking the binding of acetylcholine vesicles to the plasma membrane of the motor endplate. Neurotransmission is then restored by the sprouting of new nerve endings. It takes about three months for the original nerve endings to be restored during which time the newly sprouted nerve endings are removed. Thus, the effect of BTX-A is pharmacologically completely reversible. 20 When injected into skeletal muscle BTX-A causes a dose-dependent, reversible chemodenervation of muscle. The treatment converts paresis with muscular hyperactivity to paresis with muscular hypoactivity. The efficacy and safety of BTX-A in the management of spasticity associated with cerebral palsy have been established in a number of open-label studies, controlled studies and placebo-controlled, randomised clinical trials Applications in cerebral palsy include the management of toewalking (dynamic equinus), scissoring (adductor spasticity) and a crouching gait (hamstring spasticity) Additional applications include the management of spasticity of the upper limb and hemiplegia, and perioperative relief from pain In general, BTX-A should be considered to be a focal or regional intervention. Some groups, however, have developed an integrated multilevel approach, which in clinical effect is equivalent to a medical rhizotomy. 30 The benefits of the drug Baclofen are limited by sideeffects when administered orally. The poor lipid solubility means that the drug reaches the target tissue in very low concentrations. Administration of Baclofen directly into the subarachnoid space can circumvent this by an implanted, battery-driven, microprocessor-controlled pump. Intrathecal Baclofen (ITB) is emerging as a powerful and useful method for the management of severe generalised spasticity. 31,32 The principal indications are in children with severe spastic quadriplegia with whole-body involvement, in whom consistent reduction in muscle tone and improvements in comfort and ease of care have been reported. 33 ITB is used in walking patients in some centres but the effects of gait and function have not yet been fully studied. Some children with spasticity associated with hereditary spastic paraparesis respond particularly well. ITB is expensive, invasive and associated with a high incidence of complications some of which are life-threatening. There are reports of rapidly progressive scoliosis. Spinal deformities should be documented before ITB therapy and monitored carefully both clinically and radiologically. Mechanisms for safer and more effective delivery of medication for spasticity are clearly required. Another neurosurgical approach for the management of generalised spasticity of the lower limbs is selective dorsal rhizotomy (SDR), described by Fasano more than 20 years ago and popularised by Peacock, Arens and Berman 34 and von Koch et al 35 from South Africa. Current practice involves approaching the lumbar spine via an en-bloc laminoplasty from L1 to S1 and section of 20% to 40% of the dorsal rootlets which make up the L1 to S1 posterior nerve roots. The replacement of the laminae and the preservation of the facet joints reduces the risk of subsequent spinal deformity. SDR results in an immediate and marked reduction in spasticity accompanied by weakness of the lower limb. Intensive physiotherapy is required to regain strength and function. The reduction in spasticity is usually followed VOL. 85-B, No. 2, MARCH 2003

4 160 H. KERR GRAHAM, P. SELBER by a marked improvement in the range of movement of joints and in dynamic gait function. 36 Improvements documented by instrumented gait analysis include increased walking speed, increased stride length, a reduction in dynamic equinus, increased range of movement at the hip, knee and ankle and a reduction in the energy cost of walking. SDR reduces spasticity but has no effect on selective motor control, weakness, poor balance or fixed deformities. 19,36 Some studies suggest that orthopaedic deformities including pes planovalgus, subluxation of the hip and spinal deformities, may increase after SDR. 37,38 Uncontrolled studies of SDR reported substantial functional gains, which were not confirmed by controlled trials Spasticity is only one component of the upper motor neurone syndrome and not the most important in determining prognosis. 17,42 Weakness and loss of selective motor control are more important than spasticity and are more difficult to manage. Uncontrolled studies are subject to bias and controlled clinical trials are required to investigate efficacy. The management of spasticity in the cerebral palsies requires a multidisciplinary approach which should have representation from developmental paediatrics, neurology, physiotherapy, occupational therapy, neurosurgery and orthopaedic surgery. 17 Managing weakness in the cerebral palsies In comparison to the management of spasticity and the correction of fixed deformities, the management of weakness has been neglected until relatively recently. The traditional views were that muscle strengthening in children with cerebral palsy was neither possible nor desirable because it might increase spasticity. Recent research has shown that muscle strength can be reliably measured in children with cerebral palsy and that those who participate in strengthening programmes demonstrate increases in muscle power and improvements in function Much work remains to be done to devise appropriate strength-training programmes for children with cerebral palsy and to assess their impact over longer periods. The management of spasticity and surgery for correction of deformity may need to be combined with strength training for optimum benefits. Gait patterns in spastic diplegia are characterised by more hip and knee flexion than in spastic hemiplegia. 46,47 Bilateral weakness of the lower limbs may be more responsible than spasticity for the final gait pattern. It would seem logical to intervene for both the positive and negative features of the UMN syndrome simultaneously (Fig. 1). Orthopaedic surgery for fixed deformities Most children who have management of their spasticity by BTX-A, ITB and SDR will still require orthopaedic surgery for the correction of fixed deformities. 3,13,17-19,23 There is evidence that the optimum management of spasticity will delay the onset of such problems and, in doing so, postpone the need for orthopaedic surgery. 18,21,23,24 Contractures seem to be less prevalent and less severe in the child who has access to good management of spasticity but bony torsional deformities and pes valgus remain common. 18,37 Orthopaedic surgery has a major role in the management of children with spastic cerebral palsy by correction of fixed deformity, which in certain circumstances may improve function and quality of life. 3,13,18 As outlined above, in the second decade, appearance and integration are of central importance to the child with physical disabilities. Surgery to correct deformity will improve appearance and preserve function. Orthopaedic surgery: spastic hemiplegia In spastic hemiplegia, orthopaedic surgery has a central role in the management of the common deformities which affect the upper and lower limbs. In the upper limb these include elbow flexion, forearm pronation, wrist flexion and ulnar deviation and thumb-in-palm and swan-neck deformities in the digits. 3,13 In the spastic stage, injection of multiple target muscles with BTX-A can improve appearance and function. Corry et al 27 reported the results of the first placebo-controlled trial of injections of BTX-A in the upper limb in hemiplegia and found significant reduction in muscle stiffness and improvements in the range of movement of the joints with less robust evidence for functional improvements. Fehlings et al 28 found significant functional gains in a single-blind study, which utilised objective outcome measures. The development of validated functional outcome tools in recent years has been a crucial development. The Melbourne upper-limb assessment and the quality of upper extremity skills test (QUEST) provide orthopaedic surgeons with valid methods of measuring the functional outcome of the management of spasticity and orthopaedic surgery for deformities of the upper limbs in children with spastic hemiplegia. 48,49 Fixed deformities of the upper limb are usually corrected in a one-stage multilevel approach by a combination of management of spasticity, lengthening of fixed muscletendon contractures and correction of dynamic imbalance by tendon transfers. The goals of surgery are both cosmetic and functional. 3,13 Gait patterns in spastic hemiplegia have been classified by Winters, Gage and Hicks 46 and this provides a template for surgical management 47 (Fig. 2). Groups I and II include children with distal involvement expressed as equinus contracture and drop foot. They can be managed effectively by lengthening of the gastrocsoleus and provision of an appropriate ankle-foot orthosis. However, children with proximal involvement, groups III and IV, may benefit from instrumented gait analysis and more extensive, multilevel surgery. 50 Equinovarus deformity can be successfully managed by a combination of tendon-lengthening and tendon transfer but studies to date have either been uncontrolled or lacking in objective measures of outcome. Controversy remains as THE JOURNAL OF BONE AND JOINT SURGERY

5 MUSCULOSKELETAL ASPECTS OF CEREBRAL PALSY 161 Group I Drop foot Group II True equinus Group III Equinus/jump knee Group IV Equinus/jump knee/ hip flexion Fig. 2 Diagram showing sagittal gait patterns in spastic hemiplegia which have been classified by Winters et al 46 using quantitative kinematic data. These patterns are easily recognised and provide a useful template for surgical and orthotic management. α >90º α >90º α >90º α >90º Hinged AFO Gastrocsoleus Hinged AFO Gastrocsoleus Hamstrings/RF Hinged AFO Gastrocsoleus Hamstrings/RF Psoas Solid AFO/GRAFO Group I True equinus Group II Jump knee Group III Apparent equinus Group IV Crouch gait Fig. 3 Diagram of sagittal gait patterns in spastic diplegia according to Rodda and Graham 47 which provide a template for understanding the disorder of gait, the musculoskeletal pathology and surgical and orthotic management. α >90º α >90º α >90º α >90º Gastroc Hinged AFO Gastroc Hamstrings/RF (Psoas) Hinged AFO (Gastroc) Hamstrings/RF Psoas Solid AFO Hamstrings/RF Psoas GRAFO to the best surgical combination for this important and common deformity. Injection of the tibialis posterior and gastrocsoleus with BTX-A is effective in the younger child with spastic deformities. In most children the effects are temporary but in a few the varus deformity does not recur. 21 Split transfer of the tibialis posterior seems to be ideal for the younger child with a very flexible equinovarus deformity. 51 Split transfer of the tibialis anterior, combined with intramuscular lengthening of the tibialis posterior and gastrocsoleus, is a better option for the older child with a stiffer deformity. 52,53 Split tendon transfers are clearly more satisfactory and predictable than complete transfers. With early muscle balancing progressive bony deformities are uncommon and bony surgery should rarely be required. Orthopaedic surgery: spastic diplegia Despite new and effective means of managing spasticity, most children with spastic diplegic cerebral palsy will develop progressive musculoskeletal deformities as they grow. These include fixed contractures of the two joint muscles and a range of bony deformities, collectively referred to as lever arm disease. 54 These secondary deformities result in progressive loss of function in most children and many will benefit from correction by orthopaedic surgery. Traditionally, the child with spastic diplegia who presented with toe-walking was managed by lengthening of tendo Achillis. This was effective for the correction of the tip-toe gait but resulted in a progressive crouching gait in many children as VOL. 85-B, No. 2, MARCH 2003

6 162 H. KERR GRAHAM, P. SELBER Fig. 4 Photograph showing that gait deviations in walking children with spastic diplegia can be characterised using three-dimensional kinematics and kinetics and dynamic electromyography. Biomechanical analysis is the foundation for understanding the individual patient s gait deviations from which a prescription for integrated management may be derived, including management of spasticity, correction of deformity and orthotic prescription. Fig. 5 Photograph showing that physiological measurements in the gait laboratory are important in providing functional outcome measures after intervention. This child is wearing a face mask connected to a portable metabolic cart from which oxygen consumption and production of carbon dioxide can be measured on a breath-by-breath basis. the contractures at the knee and hip progressed. A clear consensus has emerged that orthopaedic surgery to correct gait problems should address all deformities simultaneously. 3,13,18,54,55 Single-event multilevel surgery refers to the correction of all orthopaedic deformities in one session, requiring only one hospital admission and one period of rehabilitation. Sagittal gait patterns in spastic diplegia have recently been classified by Rodda and Graham 47 who provided a management algorithm, based on the patterns (Fig. 3). The precise operative prescription is based on a full biomechanical assessment in the motion analysis laboratory. The outcome of the surgery and rehabilitation can be determined by a follow-up analysis 12 to 24 months after surgery. 54 Surgery for gait correction is practised in some centres without preoperative gait analysis but it is difficult to plan and impossible to evaluate the outcome without objective and repeatable outcome measures. However, the availability of motion analysis remains restricted to specialist centres in most countries. Randomised clinical trials are required to evaluate the role of instrumented gait analysis for the satisfaction of both the orthopaedic surgeon and the funding bodies. Instrumented analysis in modern gait laboratories includes a standardised physical examination, two-dimensional video recording of gait, three-dimensional kinematics and kinetics, dynamic electromyography, pedobarography and measurement of the energy cost of walking. 54 Biomechanical analysis has added greatly to the understanding of pathological gait patterns and provides an objective outcome measure after surgery for correction of gait (Fig. 4). However, physiological monitoring by the measurement of self-selected walking speed and the energy cost of walking (Fig. 5) complements the biomechanical measures, providing a global measure of function It is important that children who are taller and straighter after gait correction are not made weaker and slower. Correction of fixed contractures of muscle-tendon units in spastic diplegia is achieved by muscle-tendon recession or fractional lengthenings The operative procedures must be conservative, stable for early weight-bearing and preserve strength (Figs 6 and 7). The accepted operations are lengthening of the psoas at the pelvic brim by either the Sutherland or Gage technique, fractional lengthening of the medial hamstrings, transfer of rectus femoris to semitendinosus for a stiff-knee gait and recession of the distal apone- THE JOURNAL OF BONE AND JOINT SURGERY

7 MUSCULOSKELETAL ASPECTS OF CEREBRAL PALSY 163 Fig. 6 Photograph showing that in spastic diplegia spasticity and contracture affect the flexors of the hip, the knee, and the ankle which results in a sagittal gait pattern known as jump gait. In this gait pattern, management of spasticity and correction of deformity needs to be applied bilaterally, at all three levels. Fig. 7 Photograph showing that surgical correction of fixed deformities should address all three levels simultaneously with single-event multilevel surgery. urosis of gastrocnemius by the Strayer technique Open lengthening of the adductors of the hip, tenotomy of the iliopsoas at the lesser trochanter and lengthening of tendo Achillis are rarely required in spastic diplegia. 54 These procedures may result in overcorrection, which is impossible to salvage. 54,62 However, there has never been a randomised clinical trial in which operative techniques have been compared. Views on the surgical management of spastic diplegia are not supported by a high level of evidence. 63 Correction of bony torsion and of pes valgus requires rotational osteotomies and stabilisation of the foot, respectively. 54 Correction of in-toed gait and medial femoral torsion by external rotation osteotomy of the femur is very effective and the results are lasting. 64 Proximal femoral osteotomy is the procedure of choice for in-toed gait in the presence of hip dysplasia or subluxation. If the hips are stable, distal femoral osteotomy is an equally effective procedure, which offers some advantages over proximal femoral osteotomy. 65 In either case, precise correction, stable fixation and early mobilisation are essential to a good outcome. Supramalleolar osteotomy of the tibia and fibula is the best technique for correction of lateral tibial torsion. Fixation can be achieved by crossed Kirschner wires or the T plate from the AO (ASIF) small fragment set. 66 Correction of the abducted valgus foot can be successfully achieved in most children by lengthening of the os calcis, as described by Evans 67 and popularised by Mosca. 68 This procedure avoids a fusion in the hindfoot but the results may not be as durable as subtalar fusion. Severe deformities may require an extraarticular fusion of the subtalar joint by the Princess Margaret Rose technique, incorporating screw fixation and autogenous bone graft from the iliac crest. 69 Combined lengthening of the os calcis and subtalar fusion is very effective in neglected feet with severe deformities. Bony surgery in children with spastic diplegia can be associated with slow rehabilitation and loss of function. The rehabilitation programme is as important as the surgery and must be closely supervised. 54,55 Orthopaedic surgery: spastic quadriplegia The medical and orthopaedic management of the child with spastic quadriplegia or whole-body involvement is particularly challenging. Hip displacement and spinal deformities are common, are often rapidly progressive and occur in the context of multiple medical co-morbidities including epilepsy, respiratory disease, nutritional deficiencies and osteopenia. 13 The most common movement disorder is spastic dystonia, which may be successfully managed in some children by ITB. 13,19 Orthopaedic sur- VOL. 85-B, No. 2, MARCH 2003

8 164 H. KERR GRAHAM, P. SELBER gery should only be practised in the context of a multidisciplinary team, offering expertise in the management of medical co-morbidities, paediatric management of pain and intensive care. 17 The prevalence of hip displacement is approximately 1% in spastic hemiplegia, 5% in spastic diplegia and 35% to 55% in spastic quadriplegia. 13,70 Children with hip displacement and either spastic hemiplegia or spastic diplegia, have such a significant gait disorder that they are very quickly referred to the orthopaedic surgeon. However, in spastic quadriplegia the diagnosis of hip displacement is frequently delayed, which limits the management options. The reasons for delayed diagnosis are simple. Hip displacement in the spastic child is silent in the early stages and the parents, carers and paediatricians are focused on much more obvious issues such as feeding difficulties and the management of seizures. The goal of management of the hip should be early detection of abnormality by systematic screening and prevention of dislocation by simple soft-tissue surgery. 70,71 It is more effective to prevent dislocation by simple soft-tissue surgery than to subject a child to the risks of major reconstructive operations. When the latter are required, a one-stage open reduction, combined with a varus derotation and shortening osteotomy of the proximal femur and a pelvic osteotomy, offers the best prospect of longterm stability of the hip The results of salvage surgery are at best indifferent and unpredictable. Recent studies utilising CT and three-dimensional reconstruction have added to our knowledge of the pathoanatomy of hip displacement in cerebral palsy. 75,76 Defining the direction of the displacement and the location of the acetabular deficiency have a direct bearing in planning reconstructive surgery. Correction of spinal deformity is a challenging and important part of the surgical management of the children with spastic quadriplegia. Prevention of hip dislocation, fixed hip deformity and pelvic obliquity are important in minimising spinal deformity. 13 The standard care for severe spinal deformity is a long, instrumented posterior fusion to the pelvis. 13 Adequate correction may require anterior surgery if the deformity has been neglected. We know that good correction of spinal deformities can be achieved with acceptable morbidity and mortality in children with severe spastic quadriplegia. We do not know if the surgery improves the quality of life because we lack the appropriate instruments to measure it. The survival of increased numbers of children affected by cerebral palsy inevitably means an increase in the numbers of young adults with varying degrees of physical disability and extensive musculoskeletal pathology. These adults have complex needs, which few medical systems have the planning or resources to deal with. 14 Conclusions Orthopaedic surgery has much to offer in the management of many children with cerebral palsy, including those with spastic hemiplegia, spastic diplegia and spastic quadriplegia. 3,13,54 However, evidence for the efficacy of most orthopaedic operations is lacking. We run the risk of being marginalised and funding being directed elsewhere. The size of the treatment effect of injections of BTX-A in the management of spastic equinus is much less than for muscle-tendon surgery. However, the use of BTX-A is supported by several randomised clinical trials and there are no comparable controlled trials of orthopaedic surgery in children with cerebral palsy. 77 Orthopaedic surgeons have focused too much on the measurement of deformity and disability and not enough on validated functional outcome measures. The National Centre for Medical Rehabilitation and Research has developed a model to translate medical findings into clinical benefits for individuals with disabling conditions, by describing five domains of disability: pathophysiology, impairment, functional limitation, disability and societal limitation. 78 The International Classification of Impairments Disabilities and Handicaps of the World Health Organisation similarly widens the perspective from a narrow focus on disability to an emphasis on health and function in society. 79 The next generation of orthopaedic researchers in the field of disability must embrace this wider perspective or risk being isolated, their research being underfunded and their findings ignored. Orthopaedic surgery for children with cerebral palsy undoubtedly makes them different and most orthopaedic surgeons are convinced that by correcting deformities we are improving function and quality of life. We must improve the evidence for the value of orthopaedic surgery for children with cerebral palsy by appropriate clinical trials and by applying comprehensive, balanced, validated outcome measures. References 1. Standley F, Blair E, Alberman E. Cerebral palsies: epidemiology and causal pathways. Clinics in developmental medicine. London: Mac- Keith Press 2000; MacKeith RC, Polani PE. Cerebral palsy. Lancet 1958;1: Rang M, Silver R, De La Garza J. Cerebral palsy. In: Lovell WW, Winter RB, eds. Pediatric Orthopaedics 2nd ed, Vol 1. Philadelphia: JB Lippincott, Graham HK. Painful hip dislocation in cerebral palsy. Lancet 2002;359: Little WJ. On the influence of abnormal parturition, difficult labours, premature birth and asphyxia neonatorum on the mental and physical condition of the child, especially in relation to deformities. Trans Obstet Soc Lond 1962;3: Miller G, Clark GD. The cerebral palsies. Boston: Butterworth-Heinemann, Russell DJ, Rosenbaum PL, Cadman DT, et al. The gross motor function measure: a means to evaluate the effects of physical therapy. Dev Med Child Neurol 1989;31: Palisano R, Rosenbaum P, Walter S, et al. Development and reliability of a system to classify gross motor function in children with cerebral palsy. Dev Med Child Neurol 1997;39: Rosenbaum PL, Walter SD, Hanna SE, et al. Prognosis for gross motor function in cerebral palsy: creation of motor development curves. JAMA 2002;288: Ziv I, Blackburn N, Rang M, Koreska J. Muscle growth in normal and spastic mice. Dev Med Child Neurol 1984;26:94-9. THE JOURNAL OF BONE AND JOINT SURGERY

9 MUSCULOSKELETAL ASPECTS OF CEREBRAL PALSY Cosgrove AP, Graham HK. Botulinum toxin A prevents the development of contractures in the hereditary spastic mouse. Dev Med Child Neurol 1994;36: Brown JK, Minns RA. Mechanisms of deformity in children with cerebral palsy. Seminars in Orthopaedics 1989 Vol 14 No 4: Miller F, Dabney KW, Rang M. Complications in cerebral palsy treatment. In: Epps CH, Bowen JR, eds. Philadelphia. JB Lippincott Co. Complications in pediatric orthopaedic surgery 1995; Andersson C, Mattsson E. Adults with cerebral palsy: a survey describing problems, needs and resources, with special emphasis on locomotion. Dev Med Child Neurol 2001;43: Johnson DC, Damiano DL, Abel MF. The evolution of gait in childhood and adolescent cerebral palsy. J Pediatr Orthop 2002;22: Bell KJ, Ounpuu S, DeLuca PA, Romness MJ. Natural progression of gait in children with cerebral palsy. J Pediatr Orthop 2002;22: Pirpiris M, Graham HK. Management of spasticity in childhood. 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