Orthotic Management of Children with Cerebral Palsy
Christopher Morris, MSc, SR Orth
The International Classification of Functioning, Disability and Health (ICF) distinguishes impairments of body structure from activity limitations and participation exclusions.1 By definition, the impairment known as cerebral palsy (CP) describes damage to the immature brain resulting in problems with balance, coordination, and movement. Understanding the effects of such a complex condition is a constant challenge to developing treatment regimens to improve the health of children with CP. A consensus for describing the primary neurological impairment has been presented by the group for the Surveillance of Cerebral Palsy in Europe (SCPE).2 The impact of skeletal growth during childhood can compound the primary problem if muscles fail to lengthen in proportion to their adjacent long bones. Therefore, although CP is by definition a static neurological lesion, the phenotype has also been labeled with the secondary impairment of a 'progressive neuromuscular deformity.'3
Children with CP are often limited in their activities because of primary and secondary impairments. A valid and reliable means of measuring functional limitations in children with CP is now possible using the Gross Motor Function Classification System (GMFCS) for children up to 12 years old.4 The GMFCS enables clinicians to describe the severity of a child's functional limitations in one of five levels. Children in Level I are only mildly affected and can achieve most the activities of their age-matched healthy counterparts, with only modest qualitative differences. Conversely, children in Level V are the most limited in their activities and have little ability to control their head and trunk posture to counter the effects of the motor impairment and gravity. Rates of functional limitation in mobility, manual dexterity, speech, and vision, and to a lesser extent hearing and cognition, have been shown to correlate with GMFCS level.5
TREATMENT GOALS
In conjunction with other medical, surgical, and therapeutic interventions, orthoses continue to play an important role in the physical management of children with CP. Orthoses are designed with one of two primary aims: either to affect the body structure or to assist function, although for children with CP, orthoses are frequently designed to achieve both of these aims. The aims of lower limb orthotic management of CP were identified by the consensus conference convened by the International Society of Prosthetics and Orthotics6:
To correct and/or prevent deformity
To provide a base of support
To facilitate training in skills
To improve the efficiency of gait
It is clear that the first of these aims fits with interventions designed to affect the body structure, whereas the remainder involve overcoming activity limitations. These aims may similarly be applied to the role that orthotic interventions can play in the management of postural impairments of the trunk and upper limbs. However, some degree of compromise is necessary because orthoses prescribed to prevent or correct deformities can impose additional activity limitations by restricting movement.
To Correct and/or Prevent Deformity
Mobile joint deformities caused by gravity or unbalanced muscle forces can be corrected passively and the position maintained using orthoses. Fixed deformities caused by relative shortening of muscles and soft tissues and structural deformities of abnormal bone shape cannot be passively corrected and must be accommodated in orthoses. Ensuring that muscles spend more than 6 hours during each 24-hour period in an elongated position may help to prevent or reduce the rate of progressive contractures.7 However, stretching muscles using active forces for shorter periods may perhaps be more effective than maintaining a static position to increase muscle length and hence the available range of motion at joints.8
To Provide a Base of Support
Stability in any position of lying, sitting, or standing requires consideration of both intrinsic and extrinsic factors. Intrinsic stability involves controlling the position of the center of mass within the body. Extrinsic stability involves maintaining the center of mass within the supporting area. Hip abduction orthoses may improve stability and sitting balance by increasing the size of the support area, either in combination with a spinal orthosis or by encouraging independent control for the position of the center of mass of the trunk. Similarly, standing frames use hip-knee-ankle-foot-orthoses to control body position and wide bases of support to provide upright postural stability. To Facilitate Training in Skills
Normal functional development can be impeded by impairments of coordination and movement. Orthoses can maintain optimum biomechanical alignment of body segments encased within the orthosis. These effects may enable children to overcome activity limitations by focusing training on unrestricted parts of their bodies over which they have better control. Common training targets include encouraging head control by providing trunk stability or using wrist orthoses to facilitate manual dexterity when grasping objects. For lower limb orthoses, the effects also include influencing external movements acting around proximal joints by altering the line of action of the ground reaction force during standing and walking.9 There may be some motor learning effect when children repeat movements through the altered sensations provided by the orthosis.
TO IMPROVE THE EFFICIENCY OF GAIT
Children who are able to achieve upright locomotion must be encouraged to optimize their ability to achieve an efficient gait. Gage11 has described the prerequisites of normal gait:
1. Stability of the supporting leg during stance phase: requiring an appropriate foot-floor contact area, minimizing the external moments acting on the knee, and creating adequate hip abduction power to prevent the pelvis dropping on the unsupported side.
2. Clearance of the foot from the ground during swing phase: requiring adequate hip and knee flexion and ankle dorsiflexion of the swinging limb.
3. Appropriate prepositioning of the limb at the end of swing phase: created by knee extension and ankle dorsiflexion.
4. Achieving an adequate step length: by hip extension of the stance limb and unrestricted advancement of the swinging limb.
5. Conservation of energy expenditure through reduced excursion of the center of mass of the body.
Lower limb orthoses may improve gait efficiency by restoring these prerequisites through the manipulation of forces acting on the body. Orthoses may reduce energy expenditure further by decreasing the need for compensatory gait deviations to achieve locomotion.
ASSESSMENT
A thorough assessment of the child's needs is essential. The needs of each child will be influenced by the severity of their impairment and their individual activity limitations. The consensus conference document considered orthotic intervention as relating to three levels of function (i) the prestanding child (recognizing that this may be the highest level of activity for some children), (ii) the standing child, and (iii) the walking child.6
Collating the information required to define the treatment goals and therefore decide whether an orthosis will form a useful part of an overall physical management plan is a multidisciplinary task. The information required will usually include a precise diagnosis using the SCPE classification; functional gross motor status using the GMFCS; measurement of ranges of joint motion both passively and actively; selective muscle control, strength, and spasticity; and joint congruency and integrity judged by radiological investigation. In addition, an assessment of sitting and standing balance and gait analysis will be required for children with those abilities. Other factors influencing the development of a realistic plan for physical management include considering the environments in which the child interacts, behavioral characteristics, and any relevant associated conditions, such as epilepsy, gastroesophageal reflux, or the need for gastrostomy feeding tube access.
Once the treatment goals are defined, many therapeutic interventions other than orthoses are available, such as oral, intramuscular, or intrathecally administered medications, orthopaedic and neurological surgery, physical and occupational therapy, wheelchairs, walking aids and other assistive technology, and temporary splinting and casting. These interventions may be prescribed either as more efficacious and appropriate in achieving the treatment goals or to supplement and reduce the demands required of an orthosis. However, children with CP are frequently prescribed orthoses. A follow-up study of a population of children between 5 and 16 years old demonstrated that half the children were prescribed some orthosis in a 9-month period.12 This study is likely to have underestimated orthotic prescription, because the study period was shorter than the average time (10 months) in which some children outgrow their orthoses.13
Whatever the treatment goals and design of orthosis selected, a family-centered approach will encourage appropriate use of an orthosis within the prescribed treatment regimen. The health care team, including the orthotist, must therefore be well coordinated, work in partnership with the family, provide adequate general and specific information about the condition and the role of the prescribed orthosis, and support the family to ensure the orthosis is used correctly.14
ORTHOTIC PRESCRIPTION
Following the earlier recommendation to distinguish the needs of the prestanding, standing, and walking child, this review will also attempt to describe the appropriate orthotic management of children with CP with reference to the GMFCS.
PRESTANDING
GMFCS Level V, Level IV up to Age 6 Years, and Level III Before Age 2 Years
Prestanding children will spend all their time in either lying or sitting postures. Based on earlier work to develop systematic assessment protocols,15 the Chailey scales of 'levels of ability' in lying, sitting, and standing provide another framework for assessing the progress of children with postural impairments.16 Achieving the sequence of postural tasks set out in the Chailey scales requires the child to accomplish discrete improvements in motor development and mastery of balance and coordination. The acquisition of skills or alternatively the provision of postural management aids, which enable independent lying, sitting, and standing, can free the senses and upper limbs from stabilizing the body, promoting activities of dexterity and oromuscular function, thereby facilitating cognitive and social development. Although lying supports and seating systems are in principle orthoses because they apply forces to the body to compensate for the impairment, they are beyond the scope of this article because they are forms of assistive technology not usually supplied through the orthotic clinic. The children considered in this section are the most severely limited and will usually have bilateral involvement and spastic type CP.
Scoliosis
As stated earlier, children with CP who are more limited in their activities are at greater risk of contractures and therefore deformities. Children with lower levels of ambulation, corresponding to children classified with GMFCS levels IV and V, are at greater risk of scoliosis.17 Scoliosis also seems to be aggravated by the effects of gravity when affected persons are artificially placed in the sitting position.17 Rigid plastic thoracolumbar sacral orthoses (TLSOs) may reduce spinal curvature and improve sitting ability while the orthosis is worn18; however, TLSOs are unlikely to alter the rate of progressive deformity.19 For children with large structural scoliosis, surgical stabilization may be the more realistic intervention to offer.
When casting for spinal orthoses (TLSOs), it is desirable to remove the deforming axial effects of gravity. Because the treatment goal is to enable a comfortable and functional sitting posture, overcorrection may not be indicated. Tight hamstrings, as demonstrated by a reduced popliteal angle, can reduce the lumbar lordosis by posteriorly tilting the pelvis (sometimes called sacral sitting).20 Children with poor levels of sitting ability may also demonstrate excessive forward trunk leaning or thoracic kyphosis. Spinal orthoses may prevent forward leaning, and one study has suggested that the improved positioning achieved with a spinal orthosis may in fact improve pulmonary functioning.21
Hip Subluxation
The incidence of hip subluxation and dislocation is also associated with greater activity limitations. Hip dislocation requiring treatment before age 5 years was observed more commonly in children with bilateral spastic CP who were nonambulant compared with those who could walk 10 steps by age 30 months22 (that perhaps excludes children in GMFCS Levels III to I).
Orthoses can be used to abduct and flex the hip joint to increase containment of the femoral head in the acetabulum and stretch hip adductor muscles. Abducting the hips to increase the size of the base of support and anterior tilting of the pelvis, so that the center of gravity of the upper body falls within the support area, also greatly improves sitting stability. For non ambulant children, the benefits of the TLSO in controlling the position of the center of gravity and stabilizing the trunk as a single segment can be combined with hip abduction orthosis providing a stable base. Hip abduction spinal orthoses (HASOs) may be used in conjunction with wheelchair seating systems or as alternatives to the wheelchair, allowing the child to sit in regular furniture. The HASO consists of a bivalved, custom-made plastic thoracic-lumbar-sacral orthosis, closely molded around the waist and pelvis, connected to thigh cuffs with an orthotic hip joint that can be locked at 90° of hip flexion23 ( Figure 1 ). In this orthosis, maximum external control of sitting posture is provided. Because the same hip joint can also be locked with the hip extended straight, the HASO can be useful for all the activities of lying, sitting, and standing.24,25 It is also worth noting that although these HASOs will preferably hold the child in a symmetrical posture, hip adduction deformities must be accommodated. Therefore, it may be necessary to provide an asymmetrical hip position to maintain neutral pelvic posture. In some seating systems, knee blocks are additionally used to apply an axial force along the femur to the hip in a further effort to prevent pelvic rotation.22 Despite the efficacy of the HASO as a sitting orthosis, there is not yet evidence that it can alter the natural history of progressive hip migration and subluxation. Surgery may be necessary if painful subluxation is limiting activities. A similar metal and leather design can be fabricated using the same orthotic hip joint.26 However, the efficacy of the conventional nonmolded design is undermined by its limited control of the pelvis and multisegmental trunk and will usually require a separate spinal orthosis.
Postoperative Hip Orthoses
Traditionally, after hip reconstruction surgery for children with CP, hip spica casts have been applied and set at 30° of unilateral hip abduction (combined 60° angle) and 30° of hip flexion. Hip spicas take considerable time to apply at the end of an often already lengthy surgery; preclude visual inspection of the surgical wounds during the postoperative period; and can cause complications such as pressure sores. Other disadvantages of hip spicas are the need for intensive physiotherapy and usually hospital readmission to regain ranges of hip and knee joint motion that will have stiffened from immobility in the cast. The use of an orthosis in these instances may overcome some of the complications associated with using hip spica casts. The most suitable design in these instances includes a pelvic section connected to the thigh cuffs with an orthotic joint that allows incremental adjustment of flexion and abduction that can be adjusted and locked in the selected position ( Figure 2 ).
Lower Limb Deformities
Prestanding children will spend much of their time sitting and are therefore predisposed to contractures of the muscles of the lower limb. Many of the major muscles around the hip, knee, and ankle actually cross two joints. For instance, the major bulk of the calf muscle is the gastrocnemius, which crosses both the ankle and knee. To provide an efficient stretch of the gastrocnemius, preventing plantar flexion must be augmented with an orthosis to extend the knee. This may be achieved simply by simultaneously using a rigid ankle foot orthosis (AFO) and a stiffened fabric knee gaiter for short periods. Deformities of the hind- and mid-foot can develop when the range of dorsiflexion available at the ankle is reduced either by spasticity, muscle shortening, or both. Mobile equinovalgus and equinovarus ankle foot deformities can be corrected during the mold taking and cast rectification process and the position maintained using close fitting rigid AFOs. Fixed deformities, however, must be accommodated in their best corrected posture. Persistent ankle and knee deformities secondary to spasticity may benefit from intramuscular injections of botulinum A toxin to weaken spastic muscles, often combined with short periods of serial casting to facilitate ongoing management in orthoses. Maintaining reasonable foot and ankle posture will enable more comfortable posture in seating systems by allowing some of the weight of the lower limbs to be supported by footplates. If profound fixed ankle and foot deformities become established, fitting of ordinary shoes can become a problem and custom-made footwear may be necessary.
Upper Limb Management
Inadequate fine motor control and coordination may impair manual dexterity and may lead to muscle shortening and reduced ranges of movement at the elbows, wrists, and fingers. Children with bilateral spastic CP may be more affected in their lower limbs with relatively useful function in the upper limbs (sometimes called diplegia), or have four limb (total body) involvement. The principles of orthotic management are the same as in the lower limbs (that is, to stretch tight muscles, sometimes in combination with botulinum A toxin injection and serial casting). Occasionally wrist hand orthoses (WHOs) may also be employed to enable or improve hand function. The prescription of functional WHOs remains controversial but may be useful to enable or improve hand function in conjunction with occupational therapy regimens to facilitate training in skills of dexterity ( Figure 3 ).
STANDING
GMFCS Level II Before Age 2 Years, Level III After Age 2 Years, and Level IV After Age 4 Years
The objectives of orthotic management for the standing child are the same as for the prestanding child, with the additional goal of facilitating an efficient upright posture with the minimum appropriate external support. Standing, even for the nonambulant child, may be beneficial for the body structure by increasing bone density.27 The activity of standing is also important for stretching muscles and other periarticular tissues and to allow children to experience the world from the same eye-level as their peers.28 The level of each child's individual activity limitation will necessarily determine the degree and type of external support required. Clinical examination should therefore additionally include appraisal of the standing posture and balance assessment.
For most impaired children who will achieve standing (GMFCS Level IV), a hip knee ankle foot orthosis (HKAFO) will be required to maintain an upright posture, simulating Chailey Level 4 for standing ability. Two three-point force systems are used to prevent hip and knee flexion: applied to the anterior chest, posterior sacrum, anterior knees, and posterior heels. This may be fixed to a broad support base as a standing frame and used with a tray at an appropriate height. If children are able to generate adequate hip extension power, then the chest strap can be removed for short periods. Children will often require support of the ankle and foot to provide stability at the foot-floor interface during standing. Spastic equinus and any secondary hind- or mid-foot valgus or varus can either be corrected or accommodated in rigid AFOs. Heel wedges can be used to alter the inclination of the lower leg relative to the floor to accommodate fixed flexion of the hips and knees or fixed equinus.
Children who are able to pull themselves upright and maintain standing independently by holding on to an anteriorly placed piece of furniture may still benefit from some external support (GMFCS Level II before age 2 years, Level III after age 2 years). Orthoses that restrict ankle motion can be used to provide a stable base and control the line of action of the ground reaction force around the hip and knee so that training and strengthening can be targeted at proximal muscles.10
In a study of standing balance, the center of pressure under the foot was shifted more anteriorly for children with spastic equinus than for normal children, as would be expected.29 Using footwear and AFOs that resisted plantar flexion enabled the children to shift the center of pressure more posteriorly but had little effect on lateral sway characteristics. Another small study compared four children with CP with four healthy children during perturbed standing balance while barefoot and with rigid and spiral graphite AFOs.30 This study demonstrated the difficulty children with CP have in recruiting muscles to maintain balance and indicated that rigid AFOs can impose further difficulties by removing the postural adjustments that can be made at the ankle. In other studies that have examined the activity of moving from sitting to standing, children with CP and spastic equinus who were slower than healthy children performed the task faster with either rigid or hinged AFOs (perhaps GMFCS Levels II and III). However, similar children who were within 1 standard deviation of the range of normal children in achieving the task barefoot were slower when using either design of orthosis (perhaps GMFCS Level I).31 Therefore, permitting small amounts of movement at the ankle may enhance standing balance and enable the child to move from sitting to standing more easily. Children who achieve independent standing can then focus on developing skills of walking, perhaps requiring ongoing assistance of orthoses and walking aids (GMFCS Levels III and IV).
WALKING
GMFCS Levels I, II, and III After Age 2 Years and Level IV After Age 4 Years
Approximately two thirds of children with CP will achieve some level of walking ability.32 The objectives of orthotic management for the walking child are the same as for the prestanding and standing child, with the additional goal to enable the child to attain an efficient and purposeful gait. In addition to the information required in the clinical examination of prestanding and standing child, an assessment of the child's gait is necessary. The gait of children with spastic type CP is generally repeatable from step to step. However, children with ataxic or dyskinetic types of CP may be more variable and less predictable. Gait analysis requires a systematic approach to describe the patterns of joint motion and identify factors that cause pathological movements. The difficulty in analyzing the gait of children with CP is that the impairment causes gait deviations in each of the sagittal, coronal, and transverse planes and commonly involves the hip, knee, and ankle joints.
Winters'33 classification for children with spastic hemiplegia identified four distinct patterns with increasing distal to proximal involvement. For Winters Type 1 hemiplegia, which presents as equinus only in swing phase, either a posterior leaf spring or hinged AFO with a plantar flexion stop may improve foot ground clearance. For Winters Type 2 hemiplegia, when equinus persists in stance and swing phase and the knee is hyper-extended during stance, a rigid AFO is recommended. For Winters Types 3 and 4, when additional knee and hip pathology exists, orthotic management is insufficient and orthopaedic surgery is indicated.
Sutherland and Davids34 identified four patterns of knee motion in spastic diplegia. In combination with Winters classification,33 these patterns have been used to create algorithms for physical management that combine appropriate use of spasticity, musculoskeletal and orthotic interventions.35 Recommendations for orthotic intervention to improve gait efficiency are usually based on the integrity of the plantarflexion-knee extension couple during stance phase.35 This describes the normal relationship between the ankle-foot complex and the knee joint to maintain the ground reaction force (GRF) just in front of the knee during stance phase. It requires the ankle and foot to be stable, leading in the line of progression and the gastrocnemius and soleus muscles functioning to control tibial advancement.11
Children with spastic type CP commonly walk with ankle equinus.11,33,36 Making initial contact with the forefoot during walking will usually cause the line of action of the GRF to pass well in front of the knee and hip joints, causing an excessive external knee extension moment, perhaps hyperextension (or back-kneeing), and a flexion moment around the hip. Rigid AFOs that prevent plantarflexion and have been appropriately tuned can alter the line of action of the GRF to reduce the resulting abnormal moments around the knee and hip joints, prevent knee hyperextension and increase hip extension9,10 ( Figure 4 ).
For children with more severe impairment, spasticity of proximal muscles will cause the knee and hip joints to remain flexed during stance.11,33 When the GRF passes behind the knee, the increased external flexion moment will cause excessive knee flexion and crouching. AFOs that prevent dorsiflexion at the ankle can prevent knee flexion during stance by realigning the GRF in front of the knee37 ( Figure 5 ). However, whereas these orthoses are effective for paralyzed limbs, the presence of spastic or fixed flexion at the knee and hip joints means that other interventions are required to render these orthoses effective in children with CP.38 We routinely use anterior GRF AFOs, extending proximally to the tibial tubercle, in the 6 months' postmultilevel surgery to protect the weakened muscles and enable early standing and walking.
In either of the above situations, the rigid lever of the ankle and foot must also cope with premature and prolonged external dorsiflexion moment. The multisegmental structure of the ankle and foot may buckle due to the applied forces, causing hindfoot eversion or inversion and mid-foot collapse. In these circumstances, apparent dorsiflexion will occur at the expense of the structure of the ankle and foot. Therefore, when the integrity of the ankle and foot is insufficient to maintain a rigid lever, and the hind and mid-foot is at risk of deformity, it may be as important to prevent dorsiflexion as well as plantar flexion using a rigid AFO.
Because clinicians are aware that restrictive orthoses may impose additional activity limitations, orthoses should continue to facilitate, where possible, normal patterns of joint motion. Many studies have therefore attempted to compare the efficacy of rigid, hinged, PLS, and supramalleolar AFOs. A recent review of the efficacy of orthoses for children with CP could only conclude that preventing plantar flexion improved gait efficiency.39 Preventing plantar flexion has been shown to improve stability in stance phase,40 clearance in swing phase,41 prepositioning in terminal swing42 and to increase step length and walking speed.43 There is a suggestion that preventing plantarflexion may also improve energy expenditure based on oxygen consumption.44
There is no evidence to support any tone-reducing effect on gait from orthoses that incorporate specially molded footplates.45 Therefore, the prescription of supramalleolar orthoses that provide no leverage to prevent plantar flexion would seem to offer little benefit in the goal to improve gait efficiency. However, supramalleolar and foot orthoses may be beneficial to children with dyskinetic or ataxic types of cerebral palsy whose sagittal plane gait deviations are an essential mechanism for achieving ambulation or indeed for children whose equinus during gait has been improved after surgery.
Coronal and Transverse Plane Gait Deviations
Gait deviations in the coronal and transverse planes are more difficult to distinguish than those in the sagittal plane using only observational gait analysis. Leg-length discrepancy (LLD) in children with CP, which is associated with hemiplegia, asymmetrical involvement, or hip subluxation, causes either compensatory excessive flexion of the longer limb or pelvic obliquity. Pelvic obliquity caused by LLD results in true hip adduction on the longer limb and hip abduction of the shorter side and can be corrected using a shoe raise.
Pelvic rotation, torsional abnormalities, or foot deformities can change the angle of the foot in relation to the line of progression (in- or out-toeing). Apparent rather than true hip adduction occurs when internal rotation is seen in conjunction with flexion, causing the knees to come together when viewed in the coronal plane (sometimes called "scissor" gait). This occurs frequently in children with CP because of persistent skeletal anteversion of the femur,11,46 and for ambulant children is more common than true hip adduction or internal rotation at the hip joint. Hip abduction orthoses for ambulant children may therefore be of little benefit.
Although it may be possible to harness shear forces from the skin and the shape of the soft tissues to gain some rotational control using a molded thigh cuff, in general, rotational control of the hip joint using orthoses requires extension to the foot. Orthoses incorporating a flexible torque cable within the thigh segment of a HKAFO or elastic bands wound around the limb attached to AFOs create active rotational forces and can alter the foot progression angle.47 However, when the cause of internal hip rotation is persistent femoral anteversion or spasticity, twister orthoses are not advised because the applied torque can lead to excessive strain on the soft tissues of the knee joint. Therefore, torsional deformities usually require a surgical solution. In- or out-toeing may also result from excessive pelvic rotation or foot deformity when there may be no torsional component in the long bones. Mobile deformities of hindfoot inversion with associated forefoot adduction and hindfoot eversion with associated forefoot abduction can be corrected during the casting process and controlled using AFOs. Pelvic rotation, in which the child leads with the less impaired limb, is part of the primary neurological impairment and cannot be influenced by orthotic management.
EVIDENCE TO SUPPORT ORTHOTIC INTERVENTION
To date, all published studies examining the efficacy of orthoses for walking children with CP have included small numbers of children, and all but one48 have used within-subject comparison research designs. The evidence to support specific orthotic interventions for children with CP remains to be demonstrated using more robust research methods, such as randomized controlled trials with appropriate follow-up periods. The difficulties in mounting randomized controlled trials in this population are well recognized, in that CP is a heterogeneous condition with a wide range of neurological impairment.49,50 Recruiting groups of children with comparable baseline characteristics into a trial can be perceived as an obstacle. The SCPE classification2 and the GMFCS4 now enable researchers to balance groups of children of comparable impairments and activity limitations. However, clinical trials that would demonstrate any moderate but statistical significant differences between treatment groups would require multicenter collaboration to recruit enough subjects.51 There is also the difficulty of ascertaining clear and simply measured outcomes. Separate treatment goals and outcome measures must therefore be defined in the body structure and activity dimensions.1,52 Other challenges to designing clinical trials are the inconsistent arrangements for the organization and delivery of orthotic services and the confounding effects of associated interventions. Perhaps the most difficult problems to overcome are the strongly held views of clinicians and families on the merits of different orthotic interventions that prevail in the absence of good evidence.
CONCLUSIONS AND RECOMMENDATIONS
The benefits of most orthotic interventions used in physical management regimens for children with cerebral palsy remain controversial. There continues to be significant variation in the orthotic management of children with CP among treatment centers as a result of conflicting treatment paradigms.12 If there is uncertainty that the defined outcomes of orthotic management will be achieved, then there is an ethical responsibility for the individual clinician to inform families of that uncertainty and a justification to offer recruitment into a trial that may answer the question in the longer term. However, to overcome the biases of individual clinicians, consensual equipoise among health care professionals based on the prevailing controversy over different designs of orthoses must be recognized and addressed using robust research methodologies.53
This review has attempted to use the GMFCS as a framework for distinguishing treatment goals for orthotic management for children with CP. Health care pathways and physical management algorithms based on valid and reliable classification systems such as the GMFCS would help us identify the benefits and shortcomings of interventions for children with a broad spectrum of activity limitations. Certainly, the outcomes of orthotic intervention to prevent deformities must be measured against overcoming activity limitations. Therefore the inter-relationship of these key dimensions of health must be explored further using sound scientific principles.
CHRISTOPHER MORRIS, MSc, SR Orth, is a Principal Orthotist at the Nuffield Orthapaedic Centre NHS Trust; and a Graduate Student with the Nuffield Department of Clinical Medicine, University of Oxford, affiliated with the National Perinatal Epidemiology Unit, Oxford, UK. Copyright © 2002 American Academy of Orthotists and Prosthetists.Correspondence to: Christopher Morris, MSc, SR Orth, Department of Orthotics, Nuffield Orthopaedic Centre, NHS Trust, University of Oxford, Oxford OX3 7LD, U.K.; E-mail: christopher.morris@perinat.ox.ac.uk
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29. Carmines DV, Granata KP, Abel MF. Effects of dynamic ankle foot orthoses upon static balance in children with cerebral palsy [abstract]. Gait Posture. 2000;11:160.
30. Burtner PA, Woollacott MH, Qualls C. Stance balance control with orthoses in a group of children with spastic cerebral palsy. Dev Med Child Neurol. 1999;41:748-757.
31. Wilson H, Haideri N, Song K, Telford D. Ankle-foot orthoses for preambulatory children with spastic diplegia. J Pediatr. 1997;17:370-376.
32. Pharoah PO, Cooke T, Johnson MA, King R, Mutch L. Epidemiology of cerebral palsy in England and Scotland, 1984-9 Arch Dis Child Fetal Neonatal Ed. 1998;79:F21-F25.
33. Winters TF Jr, Gage JR, Hicks R. Gait patterns in spastic hemiplegia in children and young adults. J Bone Joint Surg Am. 1987;69:437-441.
34. Sutherland DH, Davids JR. Common gait abnormalities of the knee in cerebral palsy. Clin Orthop. 1993;288:139-147.
35. Rodda J, Graham HK. Classification of gait patterns in spastic hemiplegia and spastic diplegia: a basis for a management algorithm. Eur J Neurol. 2001;8(Suppl. 5):98-108.
36. Goldstein M, Harper DC. Management of cerebral palsy: equinus gait. Dev Med Child Neurol. 2001;43:563-569.
37. Saltiel J. A one-piece laminated knee locking short leg brace. Orthot Prosthet. 1969;23:68-75.
38. Harrington ED, Lin RS, Gage JR. Use of the anterior floor reaction orthosis in patients with cerebral palsy. Orthot Prosthet. 1984;37:34-42.
39. Morris C. A review of the efficacy of lower-limb orthoses used for cerebral palsy. Dev Med Child Neurol. 2002;44:205-211.
40. Miller NH, Chambers C. Dynamic versus standard AFO's: a comparison of gait parameters [abstract]. Orthop Trans. 1999;22:452.
41. Ounpuu S, Bell KJ, Davis RB 3rd, DeLuca PA. An evaluation of the posterior leaf spring orthosis using joint kinematics and kinetics. J Pediatr Orthop. 1996;16:378-384.
42. Romkes J, Brunner R. Comparison of a dynamic and a hinged ankle-foot orthosis by gait analysis in patients with hemiplegic cerebral palsy. Gait Posture. 2002;15:18-24.
43. Abel MF, Juhl GA, Vaughan CL, Damiano DL. Gait assessment of fixed ankle-foot orthoses in children with spastic diplegia. Arch Phys Med Rehabil. 1998;79:126-133.
44. Maltais D, Bar-Or O, Galea V, Pierrynowski M. Use of orthoses lowers the O2 cost of walking in children with spastic cerebral palsy. Med Sci Sports Exerc. 2001;33:320-325.
45. Crenshaw S, Herzog R, Castagno P, Richards J, Miller F, Michaloski G, Moran E. The efficacy of tone-reducing features in orthotics on the gait of children with spastic diplegic cerebral palsy. J Pediatr Orthop. 2000;20:210-216.
46. Bleck EE. Orthopaedic Management in Cerebral Palsy. London: MacKeith Press; 1987.
47. Nuzzo RM. Dynamic bracing: elastics for patients with cerebral palsy, muscular dystrophy and myelodysplasia. Clin Orthop. 1980;148:263-273.
48. Evans C, Gowland C, Rosebaum P. The effectiveness of orthoses for children with cerebral palsy [abstract]. Dev Med Child Neurol. 1994;36(Suppl. 70):26-27.
49. McConachie HR. Conceptual frameworks in evaluation of multidisciplinary services for children with disabilities. Child Care Health Dev. 1999;25:101-113.
50. Davidson LL. Evaluating child disability programmes: the role of commissioners. Child Care Health Dev. 1999;25:129-139.
51. Yusuf S, Collins R, Peto R. Why do we need some large, simple randomized trials? Stat Med. 1984;3:409-422.
52. Butler C, Chambers H, Goldstein M, Adams R, Samson-Fang L, Darrah J, O'Donnell M, Leach J, Edgar T, Abel M, Msall M. AACPDM methodology for developing evidence tables and reviewing treatment outcomes research. 1999. www.aacpdmorg
53. Freedman B. Equipoise and the ethics of clinical research. N Engl J Med. 1987;317:141-145.
Source: Journal of Prosthetics and Orthotics 2002; Vol 14, Num 4, p 150
URL: http://www.oandp.org/jpo/library/2002_04_150.asp
READ MORE - Orthotic Management of Children with Cerebral Palsy
Christopher Morris, MSc, SR Orth
The International Classification of Functioning, Disability and Health (ICF) distinguishes impairments of body structure from activity limitations and participation exclusions.1 By definition, the impairment known as cerebral palsy (CP) describes damage to the immature brain resulting in problems with balance, coordination, and movement. Understanding the effects of such a complex condition is a constant challenge to developing treatment regimens to improve the health of children with CP. A consensus for describing the primary neurological impairment has been presented by the group for the Surveillance of Cerebral Palsy in Europe (SCPE).2 The impact of skeletal growth during childhood can compound the primary problem if muscles fail to lengthen in proportion to their adjacent long bones. Therefore, although CP is by definition a static neurological lesion, the phenotype has also been labeled with the secondary impairment of a 'progressive neuromuscular deformity.'3
Children with CP are often limited in their activities because of primary and secondary impairments. A valid and reliable means of measuring functional limitations in children with CP is now possible using the Gross Motor Function Classification System (GMFCS) for children up to 12 years old.4 The GMFCS enables clinicians to describe the severity of a child's functional limitations in one of five levels. Children in Level I are only mildly affected and can achieve most the activities of their age-matched healthy counterparts, with only modest qualitative differences. Conversely, children in Level V are the most limited in their activities and have little ability to control their head and trunk posture to counter the effects of the motor impairment and gravity. Rates of functional limitation in mobility, manual dexterity, speech, and vision, and to a lesser extent hearing and cognition, have been shown to correlate with GMFCS level.5
TREATMENT GOALS
In conjunction with other medical, surgical, and therapeutic interventions, orthoses continue to play an important role in the physical management of children with CP. Orthoses are designed with one of two primary aims: either to affect the body structure or to assist function, although for children with CP, orthoses are frequently designed to achieve both of these aims. The aims of lower limb orthotic management of CP were identified by the consensus conference convened by the International Society of Prosthetics and Orthotics6:
To correct and/or prevent deformity
To provide a base of support
To facilitate training in skills
To improve the efficiency of gait
It is clear that the first of these aims fits with interventions designed to affect the body structure, whereas the remainder involve overcoming activity limitations. These aims may similarly be applied to the role that orthotic interventions can play in the management of postural impairments of the trunk and upper limbs. However, some degree of compromise is necessary because orthoses prescribed to prevent or correct deformities can impose additional activity limitations by restricting movement.
To Correct and/or Prevent Deformity
Mobile joint deformities caused by gravity or unbalanced muscle forces can be corrected passively and the position maintained using orthoses. Fixed deformities caused by relative shortening of muscles and soft tissues and structural deformities of abnormal bone shape cannot be passively corrected and must be accommodated in orthoses. Ensuring that muscles spend more than 6 hours during each 24-hour period in an elongated position may help to prevent or reduce the rate of progressive contractures.7 However, stretching muscles using active forces for shorter periods may perhaps be more effective than maintaining a static position to increase muscle length and hence the available range of motion at joints.8
To Provide a Base of Support
Stability in any position of lying, sitting, or standing requires consideration of both intrinsic and extrinsic factors. Intrinsic stability involves controlling the position of the center of mass within the body. Extrinsic stability involves maintaining the center of mass within the supporting area. Hip abduction orthoses may improve stability and sitting balance by increasing the size of the support area, either in combination with a spinal orthosis or by encouraging independent control for the position of the center of mass of the trunk. Similarly, standing frames use hip-knee-ankle-foot-orthoses to control body position and wide bases of support to provide upright postural stability. To Facilitate Training in Skills
Normal functional development can be impeded by impairments of coordination and movement. Orthoses can maintain optimum biomechanical alignment of body segments encased within the orthosis. These effects may enable children to overcome activity limitations by focusing training on unrestricted parts of their bodies over which they have better control. Common training targets include encouraging head control by providing trunk stability or using wrist orthoses to facilitate manual dexterity when grasping objects. For lower limb orthoses, the effects also include influencing external movements acting around proximal joints by altering the line of action of the ground reaction force during standing and walking.9 There may be some motor learning effect when children repeat movements through the altered sensations provided by the orthosis.
TO IMPROVE THE EFFICIENCY OF GAIT
Children who are able to achieve upright locomotion must be encouraged to optimize their ability to achieve an efficient gait. Gage11 has described the prerequisites of normal gait:
1. Stability of the supporting leg during stance phase: requiring an appropriate foot-floor contact area, minimizing the external moments acting on the knee, and creating adequate hip abduction power to prevent the pelvis dropping on the unsupported side.
2. Clearance of the foot from the ground during swing phase: requiring adequate hip and knee flexion and ankle dorsiflexion of the swinging limb.
3. Appropriate prepositioning of the limb at the end of swing phase: created by knee extension and ankle dorsiflexion.
4. Achieving an adequate step length: by hip extension of the stance limb and unrestricted advancement of the swinging limb.
5. Conservation of energy expenditure through reduced excursion of the center of mass of the body.
Lower limb orthoses may improve gait efficiency by restoring these prerequisites through the manipulation of forces acting on the body. Orthoses may reduce energy expenditure further by decreasing the need for compensatory gait deviations to achieve locomotion.
ASSESSMENT
A thorough assessment of the child's needs is essential. The needs of each child will be influenced by the severity of their impairment and their individual activity limitations. The consensus conference document considered orthotic intervention as relating to three levels of function (i) the prestanding child (recognizing that this may be the highest level of activity for some children), (ii) the standing child, and (iii) the walking child.6
Collating the information required to define the treatment goals and therefore decide whether an orthosis will form a useful part of an overall physical management plan is a multidisciplinary task. The information required will usually include a precise diagnosis using the SCPE classification; functional gross motor status using the GMFCS; measurement of ranges of joint motion both passively and actively; selective muscle control, strength, and spasticity; and joint congruency and integrity judged by radiological investigation. In addition, an assessment of sitting and standing balance and gait analysis will be required for children with those abilities. Other factors influencing the development of a realistic plan for physical management include considering the environments in which the child interacts, behavioral characteristics, and any relevant associated conditions, such as epilepsy, gastroesophageal reflux, or the need for gastrostomy feeding tube access.
Once the treatment goals are defined, many therapeutic interventions other than orthoses are available, such as oral, intramuscular, or intrathecally administered medications, orthopaedic and neurological surgery, physical and occupational therapy, wheelchairs, walking aids and other assistive technology, and temporary splinting and casting. These interventions may be prescribed either as more efficacious and appropriate in achieving the treatment goals or to supplement and reduce the demands required of an orthosis. However, children with CP are frequently prescribed orthoses. A follow-up study of a population of children between 5 and 16 years old demonstrated that half the children were prescribed some orthosis in a 9-month period.12 This study is likely to have underestimated orthotic prescription, because the study period was shorter than the average time (10 months) in which some children outgrow their orthoses.13
Whatever the treatment goals and design of orthosis selected, a family-centered approach will encourage appropriate use of an orthosis within the prescribed treatment regimen. The health care team, including the orthotist, must therefore be well coordinated, work in partnership with the family, provide adequate general and specific information about the condition and the role of the prescribed orthosis, and support the family to ensure the orthosis is used correctly.14
ORTHOTIC PRESCRIPTION
Following the earlier recommendation to distinguish the needs of the prestanding, standing, and walking child, this review will also attempt to describe the appropriate orthotic management of children with CP with reference to the GMFCS.
PRESTANDING
GMFCS Level V, Level IV up to Age 6 Years, and Level III Before Age 2 Years
Prestanding children will spend all their time in either lying or sitting postures. Based on earlier work to develop systematic assessment protocols,15 the Chailey scales of 'levels of ability' in lying, sitting, and standing provide another framework for assessing the progress of children with postural impairments.16 Achieving the sequence of postural tasks set out in the Chailey scales requires the child to accomplish discrete improvements in motor development and mastery of balance and coordination. The acquisition of skills or alternatively the provision of postural management aids, which enable independent lying, sitting, and standing, can free the senses and upper limbs from stabilizing the body, promoting activities of dexterity and oromuscular function, thereby facilitating cognitive and social development. Although lying supports and seating systems are in principle orthoses because they apply forces to the body to compensate for the impairment, they are beyond the scope of this article because they are forms of assistive technology not usually supplied through the orthotic clinic. The children considered in this section are the most severely limited and will usually have bilateral involvement and spastic type CP.
Scoliosis
As stated earlier, children with CP who are more limited in their activities are at greater risk of contractures and therefore deformities. Children with lower levels of ambulation, corresponding to children classified with GMFCS levels IV and V, are at greater risk of scoliosis.17 Scoliosis also seems to be aggravated by the effects of gravity when affected persons are artificially placed in the sitting position.17 Rigid plastic thoracolumbar sacral orthoses (TLSOs) may reduce spinal curvature and improve sitting ability while the orthosis is worn18; however, TLSOs are unlikely to alter the rate of progressive deformity.19 For children with large structural scoliosis, surgical stabilization may be the more realistic intervention to offer.
When casting for spinal orthoses (TLSOs), it is desirable to remove the deforming axial effects of gravity. Because the treatment goal is to enable a comfortable and functional sitting posture, overcorrection may not be indicated. Tight hamstrings, as demonstrated by a reduced popliteal angle, can reduce the lumbar lordosis by posteriorly tilting the pelvis (sometimes called sacral sitting).20 Children with poor levels of sitting ability may also demonstrate excessive forward trunk leaning or thoracic kyphosis. Spinal orthoses may prevent forward leaning, and one study has suggested that the improved positioning achieved with a spinal orthosis may in fact improve pulmonary functioning.21
Hip Subluxation
The incidence of hip subluxation and dislocation is also associated with greater activity limitations. Hip dislocation requiring treatment before age 5 years was observed more commonly in children with bilateral spastic CP who were nonambulant compared with those who could walk 10 steps by age 30 months22 (that perhaps excludes children in GMFCS Levels III to I).
Orthoses can be used to abduct and flex the hip joint to increase containment of the femoral head in the acetabulum and stretch hip adductor muscles. Abducting the hips to increase the size of the base of support and anterior tilting of the pelvis, so that the center of gravity of the upper body falls within the support area, also greatly improves sitting stability. For non ambulant children, the benefits of the TLSO in controlling the position of the center of gravity and stabilizing the trunk as a single segment can be combined with hip abduction orthosis providing a stable base. Hip abduction spinal orthoses (HASOs) may be used in conjunction with wheelchair seating systems or as alternatives to the wheelchair, allowing the child to sit in regular furniture. The HASO consists of a bivalved, custom-made plastic thoracic-lumbar-sacral orthosis, closely molded around the waist and pelvis, connected to thigh cuffs with an orthotic hip joint that can be locked at 90° of hip flexion23 ( Figure 1 ). In this orthosis, maximum external control of sitting posture is provided. Because the same hip joint can also be locked with the hip extended straight, the HASO can be useful for all the activities of lying, sitting, and standing.24,25 It is also worth noting that although these HASOs will preferably hold the child in a symmetrical posture, hip adduction deformities must be accommodated. Therefore, it may be necessary to provide an asymmetrical hip position to maintain neutral pelvic posture. In some seating systems, knee blocks are additionally used to apply an axial force along the femur to the hip in a further effort to prevent pelvic rotation.22 Despite the efficacy of the HASO as a sitting orthosis, there is not yet evidence that it can alter the natural history of progressive hip migration and subluxation. Surgery may be necessary if painful subluxation is limiting activities. A similar metal and leather design can be fabricated using the same orthotic hip joint.26 However, the efficacy of the conventional nonmolded design is undermined by its limited control of the pelvis and multisegmental trunk and will usually require a separate spinal orthosis.
Postoperative Hip Orthoses
Traditionally, after hip reconstruction surgery for children with CP, hip spica casts have been applied and set at 30° of unilateral hip abduction (combined 60° angle) and 30° of hip flexion. Hip spicas take considerable time to apply at the end of an often already lengthy surgery; preclude visual inspection of the surgical wounds during the postoperative period; and can cause complications such as pressure sores. Other disadvantages of hip spicas are the need for intensive physiotherapy and usually hospital readmission to regain ranges of hip and knee joint motion that will have stiffened from immobility in the cast. The use of an orthosis in these instances may overcome some of the complications associated with using hip spica casts. The most suitable design in these instances includes a pelvic section connected to the thigh cuffs with an orthotic joint that allows incremental adjustment of flexion and abduction that can be adjusted and locked in the selected position ( Figure 2 ).
Lower Limb Deformities
Prestanding children will spend much of their time sitting and are therefore predisposed to contractures of the muscles of the lower limb. Many of the major muscles around the hip, knee, and ankle actually cross two joints. For instance, the major bulk of the calf muscle is the gastrocnemius, which crosses both the ankle and knee. To provide an efficient stretch of the gastrocnemius, preventing plantar flexion must be augmented with an orthosis to extend the knee. This may be achieved simply by simultaneously using a rigid ankle foot orthosis (AFO) and a stiffened fabric knee gaiter for short periods. Deformities of the hind- and mid-foot can develop when the range of dorsiflexion available at the ankle is reduced either by spasticity, muscle shortening, or both. Mobile equinovalgus and equinovarus ankle foot deformities can be corrected during the mold taking and cast rectification process and the position maintained using close fitting rigid AFOs. Fixed deformities, however, must be accommodated in their best corrected posture. Persistent ankle and knee deformities secondary to spasticity may benefit from intramuscular injections of botulinum A toxin to weaken spastic muscles, often combined with short periods of serial casting to facilitate ongoing management in orthoses. Maintaining reasonable foot and ankle posture will enable more comfortable posture in seating systems by allowing some of the weight of the lower limbs to be supported by footplates. If profound fixed ankle and foot deformities become established, fitting of ordinary shoes can become a problem and custom-made footwear may be necessary.
Upper Limb Management
Inadequate fine motor control and coordination may impair manual dexterity and may lead to muscle shortening and reduced ranges of movement at the elbows, wrists, and fingers. Children with bilateral spastic CP may be more affected in their lower limbs with relatively useful function in the upper limbs (sometimes called diplegia), or have four limb (total body) involvement. The principles of orthotic management are the same as in the lower limbs (that is, to stretch tight muscles, sometimes in combination with botulinum A toxin injection and serial casting). Occasionally wrist hand orthoses (WHOs) may also be employed to enable or improve hand function. The prescription of functional WHOs remains controversial but may be useful to enable or improve hand function in conjunction with occupational therapy regimens to facilitate training in skills of dexterity ( Figure 3 ).
STANDING
GMFCS Level II Before Age 2 Years, Level III After Age 2 Years, and Level IV After Age 4 Years
The objectives of orthotic management for the standing child are the same as for the prestanding child, with the additional goal of facilitating an efficient upright posture with the minimum appropriate external support. Standing, even for the nonambulant child, may be beneficial for the body structure by increasing bone density.27 The activity of standing is also important for stretching muscles and other periarticular tissues and to allow children to experience the world from the same eye-level as their peers.28 The level of each child's individual activity limitation will necessarily determine the degree and type of external support required. Clinical examination should therefore additionally include appraisal of the standing posture and balance assessment.
For most impaired children who will achieve standing (GMFCS Level IV), a hip knee ankle foot orthosis (HKAFO) will be required to maintain an upright posture, simulating Chailey Level 4 for standing ability. Two three-point force systems are used to prevent hip and knee flexion: applied to the anterior chest, posterior sacrum, anterior knees, and posterior heels. This may be fixed to a broad support base as a standing frame and used with a tray at an appropriate height. If children are able to generate adequate hip extension power, then the chest strap can be removed for short periods. Children will often require support of the ankle and foot to provide stability at the foot-floor interface during standing. Spastic equinus and any secondary hind- or mid-foot valgus or varus can either be corrected or accommodated in rigid AFOs. Heel wedges can be used to alter the inclination of the lower leg relative to the floor to accommodate fixed flexion of the hips and knees or fixed equinus.
Children who are able to pull themselves upright and maintain standing independently by holding on to an anteriorly placed piece of furniture may still benefit from some external support (GMFCS Level II before age 2 years, Level III after age 2 years). Orthoses that restrict ankle motion can be used to provide a stable base and control the line of action of the ground reaction force around the hip and knee so that training and strengthening can be targeted at proximal muscles.10
In a study of standing balance, the center of pressure under the foot was shifted more anteriorly for children with spastic equinus than for normal children, as would be expected.29 Using footwear and AFOs that resisted plantar flexion enabled the children to shift the center of pressure more posteriorly but had little effect on lateral sway characteristics. Another small study compared four children with CP with four healthy children during perturbed standing balance while barefoot and with rigid and spiral graphite AFOs.30 This study demonstrated the difficulty children with CP have in recruiting muscles to maintain balance and indicated that rigid AFOs can impose further difficulties by removing the postural adjustments that can be made at the ankle. In other studies that have examined the activity of moving from sitting to standing, children with CP and spastic equinus who were slower than healthy children performed the task faster with either rigid or hinged AFOs (perhaps GMFCS Levels II and III). However, similar children who were within 1 standard deviation of the range of normal children in achieving the task barefoot were slower when using either design of orthosis (perhaps GMFCS Level I).31 Therefore, permitting small amounts of movement at the ankle may enhance standing balance and enable the child to move from sitting to standing more easily. Children who achieve independent standing can then focus on developing skills of walking, perhaps requiring ongoing assistance of orthoses and walking aids (GMFCS Levels III and IV).
WALKING
GMFCS Levels I, II, and III After Age 2 Years and Level IV After Age 4 Years
Approximately two thirds of children with CP will achieve some level of walking ability.32 The objectives of orthotic management for the walking child are the same as for the prestanding and standing child, with the additional goal to enable the child to attain an efficient and purposeful gait. In addition to the information required in the clinical examination of prestanding and standing child, an assessment of the child's gait is necessary. The gait of children with spastic type CP is generally repeatable from step to step. However, children with ataxic or dyskinetic types of CP may be more variable and less predictable. Gait analysis requires a systematic approach to describe the patterns of joint motion and identify factors that cause pathological movements. The difficulty in analyzing the gait of children with CP is that the impairment causes gait deviations in each of the sagittal, coronal, and transverse planes and commonly involves the hip, knee, and ankle joints.
Winters'33 classification for children with spastic hemiplegia identified four distinct patterns with increasing distal to proximal involvement. For Winters Type 1 hemiplegia, which presents as equinus only in swing phase, either a posterior leaf spring or hinged AFO with a plantar flexion stop may improve foot ground clearance. For Winters Type 2 hemiplegia, when equinus persists in stance and swing phase and the knee is hyper-extended during stance, a rigid AFO is recommended. For Winters Types 3 and 4, when additional knee and hip pathology exists, orthotic management is insufficient and orthopaedic surgery is indicated.
Sutherland and Davids34 identified four patterns of knee motion in spastic diplegia. In combination with Winters classification,33 these patterns have been used to create algorithms for physical management that combine appropriate use of spasticity, musculoskeletal and orthotic interventions.35 Recommendations for orthotic intervention to improve gait efficiency are usually based on the integrity of the plantarflexion-knee extension couple during stance phase.35 This describes the normal relationship between the ankle-foot complex and the knee joint to maintain the ground reaction force (GRF) just in front of the knee during stance phase. It requires the ankle and foot to be stable, leading in the line of progression and the gastrocnemius and soleus muscles functioning to control tibial advancement.11
Children with spastic type CP commonly walk with ankle equinus.11,33,36 Making initial contact with the forefoot during walking will usually cause the line of action of the GRF to pass well in front of the knee and hip joints, causing an excessive external knee extension moment, perhaps hyperextension (or back-kneeing), and a flexion moment around the hip. Rigid AFOs that prevent plantarflexion and have been appropriately tuned can alter the line of action of the GRF to reduce the resulting abnormal moments around the knee and hip joints, prevent knee hyperextension and increase hip extension9,10 ( Figure 4 ).
For children with more severe impairment, spasticity of proximal muscles will cause the knee and hip joints to remain flexed during stance.11,33 When the GRF passes behind the knee, the increased external flexion moment will cause excessive knee flexion and crouching. AFOs that prevent dorsiflexion at the ankle can prevent knee flexion during stance by realigning the GRF in front of the knee37 ( Figure 5 ). However, whereas these orthoses are effective for paralyzed limbs, the presence of spastic or fixed flexion at the knee and hip joints means that other interventions are required to render these orthoses effective in children with CP.38 We routinely use anterior GRF AFOs, extending proximally to the tibial tubercle, in the 6 months' postmultilevel surgery to protect the weakened muscles and enable early standing and walking.
In either of the above situations, the rigid lever of the ankle and foot must also cope with premature and prolonged external dorsiflexion moment. The multisegmental structure of the ankle and foot may buckle due to the applied forces, causing hindfoot eversion or inversion and mid-foot collapse. In these circumstances, apparent dorsiflexion will occur at the expense of the structure of the ankle and foot. Therefore, when the integrity of the ankle and foot is insufficient to maintain a rigid lever, and the hind and mid-foot is at risk of deformity, it may be as important to prevent dorsiflexion as well as plantar flexion using a rigid AFO.
Because clinicians are aware that restrictive orthoses may impose additional activity limitations, orthoses should continue to facilitate, where possible, normal patterns of joint motion. Many studies have therefore attempted to compare the efficacy of rigid, hinged, PLS, and supramalleolar AFOs. A recent review of the efficacy of orthoses for children with CP could only conclude that preventing plantar flexion improved gait efficiency.39 Preventing plantar flexion has been shown to improve stability in stance phase,40 clearance in swing phase,41 prepositioning in terminal swing42 and to increase step length and walking speed.43 There is a suggestion that preventing plantarflexion may also improve energy expenditure based on oxygen consumption.44
There is no evidence to support any tone-reducing effect on gait from orthoses that incorporate specially molded footplates.45 Therefore, the prescription of supramalleolar orthoses that provide no leverage to prevent plantar flexion would seem to offer little benefit in the goal to improve gait efficiency. However, supramalleolar and foot orthoses may be beneficial to children with dyskinetic or ataxic types of cerebral palsy whose sagittal plane gait deviations are an essential mechanism for achieving ambulation or indeed for children whose equinus during gait has been improved after surgery.
Coronal and Transverse Plane Gait Deviations
Gait deviations in the coronal and transverse planes are more difficult to distinguish than those in the sagittal plane using only observational gait analysis. Leg-length discrepancy (LLD) in children with CP, which is associated with hemiplegia, asymmetrical involvement, or hip subluxation, causes either compensatory excessive flexion of the longer limb or pelvic obliquity. Pelvic obliquity caused by LLD results in true hip adduction on the longer limb and hip abduction of the shorter side and can be corrected using a shoe raise.
Pelvic rotation, torsional abnormalities, or foot deformities can change the angle of the foot in relation to the line of progression (in- or out-toeing). Apparent rather than true hip adduction occurs when internal rotation is seen in conjunction with flexion, causing the knees to come together when viewed in the coronal plane (sometimes called "scissor" gait). This occurs frequently in children with CP because of persistent skeletal anteversion of the femur,11,46 and for ambulant children is more common than true hip adduction or internal rotation at the hip joint. Hip abduction orthoses for ambulant children may therefore be of little benefit.
Although it may be possible to harness shear forces from the skin and the shape of the soft tissues to gain some rotational control using a molded thigh cuff, in general, rotational control of the hip joint using orthoses requires extension to the foot. Orthoses incorporating a flexible torque cable within the thigh segment of a HKAFO or elastic bands wound around the limb attached to AFOs create active rotational forces and can alter the foot progression angle.47 However, when the cause of internal hip rotation is persistent femoral anteversion or spasticity, twister orthoses are not advised because the applied torque can lead to excessive strain on the soft tissues of the knee joint. Therefore, torsional deformities usually require a surgical solution. In- or out-toeing may also result from excessive pelvic rotation or foot deformity when there may be no torsional component in the long bones. Mobile deformities of hindfoot inversion with associated forefoot adduction and hindfoot eversion with associated forefoot abduction can be corrected during the casting process and controlled using AFOs. Pelvic rotation, in which the child leads with the less impaired limb, is part of the primary neurological impairment and cannot be influenced by orthotic management.
EVIDENCE TO SUPPORT ORTHOTIC INTERVENTION
To date, all published studies examining the efficacy of orthoses for walking children with CP have included small numbers of children, and all but one48 have used within-subject comparison research designs. The evidence to support specific orthotic interventions for children with CP remains to be demonstrated using more robust research methods, such as randomized controlled trials with appropriate follow-up periods. The difficulties in mounting randomized controlled trials in this population are well recognized, in that CP is a heterogeneous condition with a wide range of neurological impairment.49,50 Recruiting groups of children with comparable baseline characteristics into a trial can be perceived as an obstacle. The SCPE classification2 and the GMFCS4 now enable researchers to balance groups of children of comparable impairments and activity limitations. However, clinical trials that would demonstrate any moderate but statistical significant differences between treatment groups would require multicenter collaboration to recruit enough subjects.51 There is also the difficulty of ascertaining clear and simply measured outcomes. Separate treatment goals and outcome measures must therefore be defined in the body structure and activity dimensions.1,52 Other challenges to designing clinical trials are the inconsistent arrangements for the organization and delivery of orthotic services and the confounding effects of associated interventions. Perhaps the most difficult problems to overcome are the strongly held views of clinicians and families on the merits of different orthotic interventions that prevail in the absence of good evidence.
CONCLUSIONS AND RECOMMENDATIONS
The benefits of most orthotic interventions used in physical management regimens for children with cerebral palsy remain controversial. There continues to be significant variation in the orthotic management of children with CP among treatment centers as a result of conflicting treatment paradigms.12 If there is uncertainty that the defined outcomes of orthotic management will be achieved, then there is an ethical responsibility for the individual clinician to inform families of that uncertainty and a justification to offer recruitment into a trial that may answer the question in the longer term. However, to overcome the biases of individual clinicians, consensual equipoise among health care professionals based on the prevailing controversy over different designs of orthoses must be recognized and addressed using robust research methodologies.53
This review has attempted to use the GMFCS as a framework for distinguishing treatment goals for orthotic management for children with CP. Health care pathways and physical management algorithms based on valid and reliable classification systems such as the GMFCS would help us identify the benefits and shortcomings of interventions for children with a broad spectrum of activity limitations. Certainly, the outcomes of orthotic intervention to prevent deformities must be measured against overcoming activity limitations. Therefore the inter-relationship of these key dimensions of health must be explored further using sound scientific principles.
CHRISTOPHER MORRIS, MSc, SR Orth, is a Principal Orthotist at the Nuffield Orthapaedic Centre NHS Trust; and a Graduate Student with the Nuffield Department of Clinical Medicine, University of Oxford, affiliated with the National Perinatal Epidemiology Unit, Oxford, UK. Copyright © 2002 American Academy of Orthotists and Prosthetists.Correspondence to: Christopher Morris, MSc, SR Orth, Department of Orthotics, Nuffield Orthopaedic Centre, NHS Trust, University of Oxford, Oxford OX3 7LD, U.K.; E-mail: christopher.morris@perinat.ox.ac.uk
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Source: Journal of Prosthetics and Orthotics 2002; Vol 14, Num 4, p 150
URL: http://www.oandp.org/jpo/library/2002_04_150.asp
