♦ All patients with cerebral palsy have lower limb involvement
♦ Determination of the pattern of neurological involvement and the degree of selective muscle control is important when considering orthopaedic intervention
♦ The neurological insult is non-progressive but the musculoskeletal effects do progress.
♦ Specific treatment aims must be identified and realistic targets defined
♦ The appropriate treatment must be selected for the child’s age and stage of development
♦ It is important to differentiate between dynamic and fixed contractures
♦ Surgery is only one of the management options and is rarely successful if considered in isolation.
Lower limb involvement is universal in the group of disorders of posture and movement that come under the general heading of cerebral palsy. The clinical features of cerebral palsy may closely resemble those seen in older patients with traumatic head injury, stroke and near-drowning events, and the orthopaedic management of all such patients is governed by similar treatment philosophies. The aetiology of cerebral palsy is discussed in Chapter 13.3.
Classification (see Chapter 13.3)
Patients with cerebral palsy may be grouped according to which part of the body is affected. Thus, hemiplegia indicates involvement of the ipsilateral upper and lower limbs whereas diplegia means that although both sides of the body are involved, the lower limbs are most affected. The term quadriplegia has been replaced by total body involvement, reflecting the fact that those patients in whom all four limbs are affected also invariably demonstrate axial problems such as scoliosis and central problems with the bulbar musculature.
Cerebral palsy is also classified by the predominant nature of the underlying disturbance to the motor system remembering that mixed patterns are common.
♦ Spasticity, the most common abnormality and the one around which orthopaedic management is focused, is an increase in muscle tone that occurs as a response to hypersensitive stretch reflexes that a damaged cerebral cortex is no longer able to control
♦ Rigidity is characterized by an involuntary sustained muscle contraction that does not depend on stretching
♦ Dyskinetic (choreoathetoid or dystonic) cerebral palsy reflects damage to the basal ganglia, and is characterized by involuntary movements
♦ Ataxic cerebral palsy is due to cerebellar damage and features problems with balance and limb placement.
Determination of the neurological pattern is important when considering orthopaedic intervention. In general, the responses in patients displaying predominantly spastic patterns are more predictable and reproducible than those involving dyskinetic types. Impairment of selective muscle control in ataxia may limit the success of surgical procedures.
This chapter concerns patients with diplegia and the lower limb problems faced by hemiplegic patients. The hip dislocations encountered in severe total body involvement patients are covered in Chapter 13.6.
Although the incidence of cerebral palsy is not decreasing, the prevalence of different types of cerebral palsy is changing. Spastic cerebral palsy is becoming more common and athetosis less so. Furthermore, severe total body involvement cerebral palsy related to prematurity and low birth weight appears to be becoming more common than diplegia due to perinatal asphyxia.
Motor development is delayed in cerebral palsy. Children may be late in reaching motor milestones or fail to develop some skills entirely. Furthermore, they often develop abnormal motor patterns. The persistence of primitive reflexes and the absence of postural reactions at the age of 2 years are associated with a poor prognosis for future walking ability, whereas a child who is able to sit without support by the age of 2 years is likely to be able to learn to walk.
Stretching is necessary for normal muscle growth but spastic muscle resists stretching and consequently, affected muscles become relatively short during skeletal growth. Unless treated, this leads to muscle and joint contractures in the limbs, which in turn contribute to abnormal loading of the skeleton and the development of bone deformity. This deterioration is exacerbated by abnormal postures and movement control problems resulting directly from the central brain lesion. Muscle and joint contractures often deteriorate rapidly during growth spurts. The sequence of events is shown in Figure 13.4.1.
From the management point of view, it is important to differentiate between dynamic and fixed contractures as well as between mobile and fixed deformities. The term ‘dynamic contracture’ indicates that the muscle or joint in question functions through a restricted range of motion during activity while it still maintains adequate passive range. Similarly, a mobile deformity is one that can be passively corrected. Fixed contractures and deformities are not correctable passively.
Although the neurological lesion is non-progressive, the musculoskeletal consequences of cerebral palsy often change during the growing years. Dynamic contractures and mobile deformities may deteriorate and become fixed. Spastic muscle is not necessarily powerful muscle and muscle weakness is a common associated factor that will compromise function over time as both height and weight increase with growth.
Individuals with cerebral palsy often have other problems which not only influence their motor development, but which should also inform surgical management decisions. Seizure disorder, learning disability, behavioural problems, and abnormal visual perception are common. Impaired cognition may make rehabilitation from surgery difficult and prejudice the outcome of such interventions. However, it is important to remember that many people with severe cerebral palsy have average or above-average intelligence.
Central balance problems cannot be addressed by treating peripheral limb deformity; indeed, some children with severe balance problems may choose to adopt a crouched wide-based externally-rotated gait in order to lower their centre of gravity and achieve better stability.
Inherent muscle weakness has already been mentioned: any assault on spastic muscle will result in further weakening, even if (as in the case of myoneural blockade) this is temporary.
In their efforts to overcome some of their limitations, children with cerebral palsy use various compensatory mechanisms. Hemiplegic children, for example, often vault during walking to obtain clearance of their equinus foot. From the management point of view, it is important to recognize compensations. True primary problems that generate compensations should be addressed. Compensations themselves do not necessarily require treatment but if used over a prolonged period they can lead to secondary deformities.
Overview of clinical management
As mentioned in previous chapters, the care of a child with cerebral palsy is complex and challenging. Parents and other carers devote huge parts of their lives to looking after such children, for whom a mundane event such as feeding or dressing may represent a difficult and time-consuming activity. They are often determined and single-minded in their search for treatments, a wide variety of which are advertised on the Internet although they are often scientifically unsubstantiated.
The management of children with cerebral palsy requires a multidisciplinary approach because of the wide-ranging nature of their problems (see Chapter 13.3 , Figure 13.13.4). It must be remembered that musculoskeletal problems are only one aspect of these children’s lives. Coordination between the various disciplines is important, as families may receive conflicting advice or information regarding therapy: a further source of frustration for the family.
Setting up priorities and defining realistic targets is crucial in the management of children with cerebral palsy. Indications for orthopaedic treatment are not always clear. Therefore, when approaching a child and their family it is important to clarify the family’s perceptions of the child’s orthopaedic problems, their priorities in his or her management, and their expectations from treatment.
The diagnosis of cerebral palsy is usually made before a child is referred for an orthopaedic opinion. However, occasionally, the orthopaedic surgeon will have the opportunity to make the diagnosis. The possibility of cerebral palsy should always be considered in a child presenting as a toe-walker or with a limp.
It is important to obtain as full a perinatal history as possible. In particular, it is essential to know the neurological type of cerebral palsy as this helps determine orthopaedic management. It is helpful if the child has already been seen and investigated by a paediatric neurologist.
The date at which motor milestones have been attained should be recorded as these give some indication as to what future achievements are possible. A child who cannot sit unsupported at 2 years of age or who has not walked by 4 years is unlikely to walk.
The current walking status should be noted (Box 13.4.1). It is important to establish how well they walk and whether this is stable, improving, or deteriorating. Community walkers can walk reasonable distances outdoors and the approximate walking distance or time should be recorded. Household walkers only walk indoors. Therapeutic walkers walk only limited distances under supervision and do not use walking as their main means of mobility. The use of any walking aids or orthoses is noted. Current or previous therapy and its frequency should be recorded, together with the use of postural management devices such as sleep management systems and standing frames. At the end of this assessment it should be possible to assign a Gross Motor Function Classification System (GMFCS) level to the child (see Chapter 13.3, Figure 13.3.3). This is a useful, clinically validated indicator of motor function that assesses the child’s progress during growth.
The history should also include the presence of associated conditions and details of any previous treatments and their outcomes (Box 13.4.2). It is important to maintain respect for the patient: whenever age and cognition allow, questions should be addressed to the child by name.
The effect of an unfamiliar or uncomfortable environment and a rushed consultation will be to increase spasticity and make meaningful examination difficult.
The clinical examination starts with an observation of posture: standing, sitting, and lying. Head and trunk control and limb posture will give an impression of the child’s level of motor development. Balance reactions and primary reflexes may be observed and involuntary movements and obvious skeletal deformities recorded.
Lower limb examination assesses the passive range of motion of all joints and the presence of any fixed contractures (Box 13.4.3). Thomas’s test detects a fixed flexion contracture of the hip but if a knee contracture is also present, the test should be performed with the patient’s pelvis at the end of the table. Alternatively, Staheli’s test is used, where prone hip extension is tested with the patient’s pelvis at the edge of the couch.
Femoral anteversion is measured clinically with the patient prone and the knee flexed at 90 degrees. The hip is rotated until the greater trochanter reaches maximum prominence laterally. The angle between the tibia and the vertical is then equal to the femoral anteversion. From this position, the total arc of hip rotation can be assessed.
Hip abduction should be tested first with both hips and knees in maximum extension. Phelp’s test differentiates limited abduction due to adductor tightness from that due to hamstring (mainly gracilis) tightness. Abduction is tested with the knees extended and then with knee flexion: if flexion improves abduction the limitation in abduction is due mainly to hamstring tightness.
The popliteal angle assesses hamstring tightness. With the patient supine, both hip and knee are flexed to 90 degrees, the knee is then brought to maximum extension: the angle between the tibia and the vertical line is the popliteal angle. Normal subjects have a popliteal angle of less than 30 degrees. In the same position, fast extension of the knee is attempted. Spasticity of the hamstrings will prevent extension before the maximum ‘passive’ popliteal angle is reached. This test measures dynamic hamstring spasticity.
Spasticity of the rectus femoris muscle can prevent knee flexion in the swing phase of gait. It is assessed by the Duncan–Ely test. With the patient supine, the knee is flexed rapidly. If the rectus is spastic, it will contract, flexing the hip joint and causing the patient’s buttock to lift off the couch. If the same is observed with slow knee flexion of the knee, a fixed contracture of the rectus is present.
A shortened calf complex (gastrocnemius and soleus) presents as reduced ankle dorsiflexion. Silverskjold’s test involves assessing dorsiflexion with the ipsilateral knee flexed and extended. As the muscle origins of gastrocnemius and soleus originate above and below the knee respectively, this test differentiates between shortening in the two muscles. In estimating dorsiflexion it is important not to allow any hindfoot valgus (as this creates a spurious correction of equinus).
Lower limb examination also includes measurement of muscle power. This can be particularly difficult in the presence of spasticity and impaired selective muscle control. However, measurement of the main muscle groups should be attempted using the Medical Research Council scale. If selective muscle control is so poor that voluntary contraction of major muscle groups, such as the hip or knee extensors is impossible, this should be recorded.
An appropriate neurological examination of the child with cerebral palsy should be performed. The modified Ashworth scale (Table 13.4.1) is used to assess spasticity and the confusion test measures selective muscle control. A child without selective control of ankle dorsiflexion shows contraction of the tibialis anterior muscle when asked to flex the hip against resistance: a positive confusion test.
Table 13.4.1 The Modified Ashworth Scale (Bohannon and Smith 1987)
No increase in muscle tone
Slight increase in muscle tone, manifested by a catch and release or by minimal resistance at the end of the range of motion when the affected part(s) is(are) moved in flexion or extension
Slight increase in muscle tone, manifested by a catch followed by minimal resistance through the remainder of the range of motion but the affected part(s) is(are) easily moved
More marked increase in muscle tone through most of the range of movement, but the affected part(s) is (are) easily moved
Considerable increases in muscle tone, passive movement difficult
Affected part(s) is (are) rigid in flexion or extension
Cerebral palsy is a disorder of movement and posture; in the ambulant child, examination of the lower limb is incomplete without an assessment of walking. The conventional static physical examination often fails to reveal the dynamic posturing adopted as soon as a child assumes an upright weight-bearing position: in the past, failure to appreciate the variable and dynamic nature of these postures has resulted in inappropriate surgery. Mistakes have also been made as a result of considering one joint segment in isolation and from failing to realize that the effects of muscle activity at one level (e.g. the ankle) have consequences at distant sites (e.g. the hip). Such relationships can be appreciated only through evaluation of an individual’s gait pattern. A knowledge of normal gait is essential before one can appreciate the errors that occur in cerebral palsy (Figure 13.4.2).
Gait analysis involves the systematic study of the body’s mobile segments and joints during locomotion. Movement is studied separately in the three orthogonal planes, namely sagittal, coronal, and transverse. Observational gait analysis employs video recordings in normal and slow motion to obtain qualitative information about gait. Instrumented gait analysis requires sophisticated laboratory equipment. Kinematic information on the three-dimensional movement of body segments and joints is derived from data generated from cameras tracking markers placed on anatomical landmarks. Data from force platforms relates forces occurring during gait to the kinematic data in order to produce information on moments and powers around joints during gait: kinetic information. Dynamic electromyography via surface electrodes or fine wires provides information on the pattern of muscle activity during gait. This is significantly deranged in many people with cerebral palsy. Energy expenditure is estimated by measuring oxygen consumption.
The information obtained during observational and instrumented gait analysis, combined with the clinical history and examination, aids the understanding of gait deviations and helps plan management. The reliability and reproducibility of gait data have been demonstrated and gait analysis is used in most centres that treat children with diplegic cerebral palsy (Figure 13.4.3). It is also a well-established outcome measure. However, instrumented gait analysis is only a tool that guides management: it should not be used as a prescriptive device that ignores the many other considerations surrounding surgical management of cerebral palsy.
Different treatments or management regimens are appropriate for different children at different stages of their growth and development.
From the musculoskeletal viewpoint, the priority in the early years is to maintain muscle length and promote muscle growth in order to minimize risk of contracture and deformity. Muscle grows rapidly in the early years of life, doubling its length in the first 4 years. It takes another 12 years to double again. It is thus sensible, if possible, to avoid surgical interference during these critical early years.
Physiotherapy has a central role in the management of young children with cerebral palsy. It focuses on assisting motor development whilst preventing the development of deformity and contractures. Serial casting to improve passive range may augment joint range and muscle stretching regimens.
There are many different schools of physiotherapy and related techniques such as conductive education that will not be discussed in this chapter. Claims that one method is better than another are all hampered by a lack of randomized controlled trials. However, it is reasonable to accept that some form of structured physical therapy is of importance in the child with cerebral palsy.
Orthoses are used in children with cerebral palsy to aid function and prevent deformity. Immobilizing a muscle in an elongated position provides passive stretching and enhances its longitudinal growth. Orthoses also provide joint stability during gait. Ankle–foot orthoses (AFOs) stabilize the ankle and foot from the early stages of motor development (Figure 13.4.4). An orthosis can also use the ground reaction force during weight bearing to stabilize more proximal joints. Thus, the ground reaction AFO (GRAFO) aids knee extension. This rigid orthosis transfers the ground reaction force applied at the forefoot area to the pretibial area, encouraging extension of the knee (Figure 13.4.5).
Orthoses are used for the postural management of non-ambulant patients. Hip orthoses provide hip abduction in patients at risk of hip dislocation. Standing frames of various designs are used to support patients in the upright position. This is thought to help with the prevention of contractures and osteoporosis. The upright posture is also beneficial for gastrointestinal and urinary tract function, as well as morale.
Nerve blocks and botulinum toxin
Spasticity can be reduced by blocking the reflex arc. The previous practice of efferent nerve destruction using agents such as phenol has been abandoned in favour of localized interruption at the motor endplate (myoneural blockade). Although this can be done successfully with diluted (50%) ethanol, it is more commonly performed using botulinum toxin-A (BTA), a neurotoxin derived from Clostridium botulinum.
BTA prevents the release of acetylcholine at the motor endplate which results in reduced neural stimulation of the muscle. Over a period of 3–6 months new nerve ends sprout that allow the muscle function to return.
BTA is given as an intramuscular injection into the region of the muscle where the motor end plates are concentrated. Local anaesthetic, often combined with sedation, is used for the injection. Reduced spasticity should be noticed within a few days. BTA is effective in the presence of dynamic rather than fixed contractures: it has been shown to be effective in the treatment of dynamic equinus and is often combined with serial casting for more resistant contractures but there is no supportive evidence for this practice.
The long-term effects of treatment with BTA are unknown, although isolated histological studies of muscle that has been repeatedly treated with BTA are showing evidence of long-term damage and atrophy. To date, treatment has not been shown to prevent fixed contractures or delay the need for surgery. Views on optimal dose and frequency of injections vary. Potential complications, although rare, include local or generalized allergic reaction, fatigue, gastric dilatation, and temporary urinary incontinence.
Baclofen is used as a systemic drug to control spasticity. However, the dosage required to reduce spasticity is often high leading to undesirable effects, such as drowsiness and confusion. Intrathecal use was introduced for patients with predominant lower limb spasticity. Low doses of baclofen are administered intrathecally via an implanted catheter and pump usually sited in the right iliac fossa (see Chapter 13.6, Figure 13.6.4). A test dose precedes implantation to confirm that the drug is effective for the individual patient at a reasonable dosage. Recharging of the pump or modification of the rate of drug delivery is possible on an outpatient basis. Close patient monitoring and a well-organized team are necessary. Potential complications include leakage of cerebrospinal fluid, migration of the catheter, and infection. The method does reduce lower limb spasticity in children with cerebral palsy.
Selective dorsal rhizotomy
This neurosurgical procedure reduces lower limb spasticity in diplegic patients. The operation involves partial (25–40%) division of the posterior nerve roots from L1 to S1. Functional improvement has been documented in the short term.
Patient selection is important and those with neurological involvement other than spasticity must be excluded. Rhizotomy should be performed before the development of any significant contractures. Muscle weakness is unmasked and a secondary spinal deformity may develop.
The main indication for lower-limb surgery in the walking child is preservation or improvement of walking function. Unlike the totally involved child with a dislocating hip, pain is not a common problem apart from a group with intransigent anterior knee pain. Similarly, cosmetic considerations are rarely an indication for surgery in this group in contrast to patients with upper limb problems.
Deformity is common in children with cerebral palsy and its presence is not, in itself, an indication for intervention. The deformity must be responsible for current functional impairment or at risk of impairing future function if left unchecked.
The ability to walk and to continue walking is seen by parents and some clinicians as the ultimate goal but overall, patients themselves do not rank the ability to walk as highly as the ability to communicate effectively or to be independently mobile. Many teenagers are encouraged to struggle on with a laborious energy-inefficient assisted gait in the face of increasing weight and increasing demands on their time from other sources when they would be able to lead a more fulfilling and independent life as chair-users.
During the process of defining targets of treatment and planning intervention the potential risks and complications of any procedures should also be discussed as these can outweigh any potential benefit.
The vast majority of children with hemiplegic cerebral palsy maintain their ability to walk into adulthood. Orthopaedic referral is usually related to gait abnormalities: delayed or asymmetric walking, leg-length discrepancy, or unilateral equinus deformity. Hypertonia, brisk reflexes, and ipsilateral upper limb involvement lead to the diagnosis of hemiplegia. Posturing of the ipsilateral upper limb by flexing the elbow during gait is a subtle but important sign of a mild hemiplegia (Figure 13.4.6).
Winters et al. (1987) attempted to classify hemiplegic gait according to severity of involvement (Table 13.4.2). They suggested treatment choices for the four different types of hemiplegic gait in their classification. AFOs help with type 1 and some type 2, for fixed equinus in types 2, 3, and 4 surgery may be indicated but in types 3 and 4 management must address problems around the hip and knee simultaneously.
Table 13.4.2 Winter’s classification of the hemiplegic gait
Equinus in swing phase of gait only (e.g. a foot drop). This can be treated with an AFO
Equinus throughout the gait cycle, with either toe contact only or toe–heel contact and compensatory hyperextension of the ipsilateral knee
Involvement of the hamstrings and rectus is observed and there is increased knee flexion throughout the gait cycle
The hip flexors and adductors are affected and internal hip rotation is observed
More recently, Hullin et al. described another classification of hemiplegic gait based on kinematic and kinetic gait data. The aim of this classification was to highlight the aetiology of various gait deviations (Table 13.4.3).
Table 13.4.3 Hullin classification of hemiplegic gait
A drop-foot pattern associated with weak anterior tibial muscles
Characterized by knee flexion throughout stance due to a functionally tight gastrocnemius with normal hip extension
Persistent knee and hip flexion due to functionally tight gastrocnemius and hip flexors
Knee hyperextension and ‘tibial arrest’ associated with a functionally tight soleus
Persistent ankle dorsiflexion with knee hyperextension, the latter compensates for weak or spastic quadriceps
The most common foot deformities in hemiplegia are equinus and equinovarus. Spasticity of the gastrocnemius is the primary cause but weakness of the dorsiflexors and the peronei often contributes. Spasticity of the tibialis posterior muscle may also be present. Planovalgus deformity with persistent hindfoot equinus and a collapsed midfoot is much more commonly seen in diplegia.
Clinical examination identifies the muscles responsible for the deformity and distinguishes between the hindfoot varus caused by an overactive tibialis posterior and the forefoot adductus and supination caused by an unopposed tibialis anterior.
Equinovarus foot deformity causes clearance problems during the swing phase of gait as well as stance phase instability as the foot turns into varus and inversion. Furthermore, the ipsilateral knee is subjected to abnormal loading and a tendency to hyperextension. Compensatory hip flexion may be observed.
The severity of the deformity depends on the age of the patient and the degree of involvement. A flexible deformity in young patients becomes more rigid with age although the true natural history is unknown. Some hemiplegic patients develop a fixed equinovarus foot deformity before skeletal maturity. Weight-bearing on a deformed foot should lead to degenerative changes in adult life but there are no long-term studies to confirm this.
The flexible deformity can be treated conservatively. Treatment aims are to improve gait and prevent a fixed deformity. Physiotherapy stretching regimens are used and an AFO maintains the foot in the neutral position, improving gait whilst protecting hip and knee from abnormal loading. BTA injections in the gastrocnemius and the tibialis posterior reduce spasticity. The treatment of fixed deformities may involve surgical lengthening of contracted muscles. In principle, simple Z-lengthening of the tendon should be avoided as this allows further contraction of the muscle belly with consequently reduced power and reduced stimulus to grow. When possible the muscle–tendon unit is lengthened as a whole by means of aponeurotic or intramuscular lengthening techniques.
In addition to muscle lengthening, tendon transfer surgery is frequently performed to achieve a longer lasting balance to muscle action around the foot. Depending on the major source of deformity, either the tibialis anterior or posterior tendons can be transferred laterally. Tibialis anterior is often transferred in its entirety whilst split tendon transfers work well for both tibialis anterior and posterior with the split tendons acting like the reins on a horse to control the mid/fore foot. The split anterior tibial transfer is popular: the lateral half of the tendon is sutured to the intact peroneus brevis or transferred more distally via a bone tunnel. This operation works well in conjunction with simple lengthening of the tibialis posterior and gastrocnemius muscles.
Muscle/tendon lengthening is not recommended in early life when rapid muscle growth is occurring: failure to heed this advice results in a high recurrence rate. If surgery is delayed until the age of 7–8 years, the risk of recurrent equinus is minimal.
In the older child with significant fixed deformities, bony surgery may be necessary. This should be combined with lengthening of the deforming muscles. Hindfoot varus is addressed with a calcaneal osteotomy whilst additional deformity may require appropriate midfoot osteotomies. Triple fusion should be reserved only for the severe, symptomatic and rigid equinovarus foot
The hip and knee
Hip dysplasia is uncommon in hemiplegia and dislocation rare.
Femoral derotation to correct anteversion and internal rotation of the leg during gait can be rewarding. It improves gait and prevents excessive knee loading. Extension and valgus can be included in the osteotomy to correct flexion and adduction at the hip. Most hemiplegic patients have a degree of pelvic rotation during gait, with the affected side retracted. This persists following derotation femoral osteotomy and can lead to unacceptable external rotation of the leg postoperatively if the femoral anteversion was corrected fully.
Operations around the knee are rarely indicated. Hamstring lengthening to correct flexion contracture can sometimes be combined with equinus foot correction. As in diplegia (see (below) spasticity of the rectus and patella alta may contribute to anterior knee pain. Treatment is challenging and in most cases is for symptoms only. Interference with the quadriceps-patellar mechanism invites many problems including failure to relieve pain and exposing underlying weakness of the knee extensors.
Neurological involvement of the affected lower limb results in reduced growth and a leg length difference is common. The discrepancy is rarely more than 1–2cm and can work to the child’s advantage aiding clearance of the equinus foot in swing phase. For this reason, correction of the equinus deformity may need to be followed by provision of a shoe raise.
When the leg length discrepancy is more marked, gait compensations may be seen. These include increased hip and knee flexion on the unaffected side and pelvic obliquity. A shoe raise is usually all that is necessary, with contralateral epiphysiodesis being reserved for patients with marked discrepancies and relatively mild involvement.
The orthopaedic management of children with diplegia relates mainly to problems with their gait. Diplegic patients often have mild upper limb involvement affecting their ability to use walking aids (Figure 13.4.3).
At the severe end of the diplegic spectrum, lower limb involvement is marked, primitive reflex patterns persist, and upper limb involvement is pronounced. This group of patients (resembling the milder end of quadriplegic cerebral palsy) may lose their ability to walk as growth progresses and contractures develop. In contrast, the gait pattern of a child with mild spastic diplegia may seem normal to the casual observer, their problems limited to minor problems with tripping, balance and endurance. It has been suggested that 85% of children with diplegia maintain their ability to walk in the long term but this probably excludes many of the more severely involved children at the poorly defined interface between diplegia and total body involvement.
Diplegic gait is complex. The child with diplegia is delayed in acquiring standing and walking skills. Initially, an extensor pattern of activity is common, featuring a combination of adducted hips (‘scissoring’), stiff extended knees, and ankle equinus (toe-walking). As the child grows, the biarticular muscles (hamstrings, rectus femoris, and gastrocnemius) are the prime targets of impaired control and increased tone, leading to hip and knee flexion contractures and increasingly fixed equinus. The hips become increasingly internally rotated. The equinus is followed by a progressive planovalgus deformity, collapse of the longitudinal arch, and forefoot abduction: the so-called ‘mid-foot break’ (Figure 13.4.7). However, gait variation is infinite, and a classification of diplegic gait has not yet been possible.
The general principles of spasticity management apply. Joint ranges and muscle length are maintained, encouraging the acquisition of assisted standing and walking skills, with the help of orthoses. AFOs control equinus and improve limb stability. Myoneural blocks of the gastrocnemius reduce dynamic equinus and encourage a heel-toe gait pattern.
As with hemiplegic patients, surgery should be deferred when possible until the child is 7–8 years old as the risk of recurrent contracture following muscle lengthening at this age is low and any alteration in neural patterning (‘neuroplasticity’) that might have compensated for some of the centrally-mediated gait problems has been exhausted. Lastly, at this age, the concept of extensive surgery and rehabilitation can be explained and understood and some degree of cooperation expected.
Single-event multilevel surgery
In the past, poor understanding of the diplegic gait pattern compounded by an inappropriate reliance on static as opposed to dynamic assessment, frequently led to young children undergoing repeated operations each followed by an extensive period of rehabilitation.
The development of gait analysis has led to a much better understanding of the problems faced in spastic diplegia, and in particular how it is inappropriate to consider a joint or limb segment in isolation. This improved understanding, led to the concept of single-event multilevel surgery (SEMLS) in which, following detailed preoperative gait analysis, all gait abnormalities are treated in a single operative procedure with a single period of rehabilitation. This principle has been developed over the past three decades and has changed the management approach to children with diplegic cerebral palsy.
Multilevel surgery includes a variety of procedures tailored for the individual patient. Soft tissue procedures to correct fixed or dynamic contractures are guided by the principle of ‘lengthening without weakening’. Extensive soft tissue releases are avoided. Judicious lengthening is performed, usually at the musculotendinous junction. The muscles crossing two joints appear to be more affected in cerebral palsy, probably because of their different function at each joint and thus inevitably more complex neurological control. These biarticular muscles frequently require surgical intervention (Box 13.4.4).
Calculations of muscle length based on gait-analysis models can assist surgical decision-making. For example, the hamstrings in crouched gait are more often than not relatively long, not short.
Another biarticular muscle, the rectus femoris, is also often affected: activity of the spastic rectus in swing prevents adequate knee flexion and causes foot clearance problems. A positive Duncan–Ely test, together with reduced sagittal knee movement and electromyographic confirmation of rectus activity in swing characterizes this problem which can be dealt with by posterior transfer of the rectus to the sartorius or gracilis.
Excessive hip internal rotation results in the knee and ankle acting across the direction of body movement, which often causes a valgus thrust at the knee. Femoral derotation osteotomy either proximally or distally restores alignment. Compensatory external tibial torsion can be addressed by a simple supramalleolar derotation osteotomy.
Knee flexion contracture is a major problem in the older child with diplegia. Soft tissue surgery alone is unlikely to give good results and enthusiasm for bony surgery to address residual flexion contractures has been revived. Supracondylar knee extension osteotomies with or without accompanying distal transfer of the tibial tuberosity have been recommended. In the skeletally immature child the same result can be obtained safely and simply by anterior hemieiphysiodesis of the distal femoral physis. This has the advantage of a slow correction, allowing the soft tissues to adapt to both sides of the gradually extending knee (Figure 13.4.8).
Osteotomies to correct rotational malalignment of the leg and resulting abnormal moments across joints are included as necessary. Femoral anteversion affects the lever arm of the abductors and often causes a valgus thrust at the knee. Tibial derotation may be indicated in some children.
Surgery to correct foot deformity is indicated in a number of children. As a rule, there is no place for muscle lengthening or tendon transfer surgery in the valgus foot in diplegia, with the exception of the gastrocnemius, whose contracture may be responsible for exacerbating the valgus. Severe hindfoot valgus that is impeding gait and causing pain may be treated by extra-articular subtalar arthrodesis. A calcaneal lengthening osteotomy treats the valgus foot with a collapsed longitudinal arch and forefoot abduction. The operation offers good correction of all three elements of the deformity in the reasonably flexible foot and can be combined, if necessary, with a subtalar arthrodesis. Gastrocnemius lengthening to correct equinus may be necessary. Triple fusion is reserved for the severely deformed, rigid, and symptomatic foot. Hallux valgus is treated by arthrodesis of the first metatarsophalangeal joint with recognition that the deformity is often secondary to more proximal midfoot deformity which may need addressing.
Multilevel operations should be planned and performed in centres where there is an appropriate interest and expertise and multidisciplinary approach. Careful assessment of potential patients, carers, and local support services is needed to ensure good patient selection and detailed planning is essential to ensure that there is a seamless transition from hospital to community care for rehabilitation. Experienced paediatric anaesthetists, postoperative epidural analgesia, and pain teams are essential to ensure that the patient does not enter into the pain/spasm/pain spiral that causes so much distress and which is responsible for many poor operative results. A comfortable, confident child is able to mobilize quickly, be discharged promptly and continue rehabilitation at home. Rehabilitation may continue for as long as 12–18 months.
Midterm results of multilevel surgery or of specific procedures are encouraging but studies into adult life are required to establish the long-term results. Such studies are difficult to conduct due to the inherent variability in patient characteristics, use of other treatment modalities and ethical issues over the use of control groups.
Mild hip dysplasia is common in diplegic cerebral palsy. As before, the incidence is difficult to ascertain due to the difficulty with diagnostic labelling at the severe end of the diplegia spectrum. The ability to walk does not exclude the possibility of progressive hip subluxation and hip monitoring should be part of the regular follow-up of these patients. The management of hip subluxation and dislocation is considered in the following section on the management of patients with total body involvement.
Lower limb management in the adult
Increasing height and weight in the teenager expose underlying problems with muscle weakness. Those who as younger children coped well, ‘walking on their spasticity’, find to their frustration and disappointment that despite maintenance of joint ranges their exercise tolerance decreases significantly in early adult life. Major surgical interventions are not generally indicated for fear of contributing further to the weakness. Appropriate management involves advice regarding regular exercise (in gyms and swimming pools), with occasional courses of physiotherapy to target specific problems. Increasing crouch posture with a contracted and weak quadriceps leads to a high-riding patella and patellofemoral joint problems. This in turn leads to increasing reliance on walking aids. There is no reliable operative solution. Degenerative hip disease occurs in the older physically active patient with diplegia and this is best treated with total hip replacement. Overall, the natural history of diplegia in adult life is unclear. Moreover, the influence of orthopaedic treatment on the long-term walking potential of diplegic patients is unknown.
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