Children with cerebral palsy are prone to development of musculoskeletal deformities. The underlying neurlogic insult may results in a loss of selective motor control, an increase in underlying muscle tone, and muscle imbalance, which can lead to abnormal deforming forces acting on the immature skeleton. The severely involved child is one who is at increased risk for developing progressive musculoskeletal deformities. Close surveillance and evaluation are key to addressing the underlying deformity and improving and maintaining overall function.
Key points
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Children with cerebral palsy are prone to development of musculoskeletal deformities.
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The underlying neurlogic insult may results in a loss of selective motor control, an increase in underlying muscle tone, and muscle imbalance, which lead to abnormal deforming forces acting on the immature skeleton.
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The severely involved child is one who is at increased risk for developing progressive musculoskeletal deformities.
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Close surveillance and evaluation are key to addressing the underlying deformity and improving and maintaining overall function.
Introduction
Orthopedic management of children with cerebral palsy is a challenging task. The presentation is highly variable, ranging from those with mild clinical manifestations to those who are severely involved. The critical part in the initial assessment of children with cerebral palsy is the identification of risk factors for development of deformities so that attempts can be made to circumvent these events. This, in turn, maintains or improves a child’s overall function.
Cerebral palsy is characterized by an injury or insult to the immature brain. This may occur before, during, or up to 5 years after birth. The pathology in the brain is permanent and nonprogressive. It results in a wide variety of postural and movement disorders. Clinical manifestations are determined by the timing of the injury and whether they occur in the preterm (immature) or term (mature) infant. The underlying pathology can point to probable patterns of involvement. An immature or preterm infant with periventricular leukomalacia typically presents with spastic diplegia, whereas a child with periventricular hemorrhage is more likely to present with hemiplegia. Cerebellar involvement may present with hypotonia and ataxia. Occasionally, more than one lesion exists in the brain, resulting in a mixed presentation. A full-term child with watershed ischemia between the anterior and middle cerebral artery presents with quadriparesis whereas a focal ischemic injury in a full-term child presents with hemiparesis. Although the brain lesion is static, its manifestations are progressive. The primary manifestations of the neurologic insult include loss of selective motor control alteration in muscular balance and muscle tone abnormalities. This results in secondary manifestations of abnormal growth and development of the musculoskeletal system. It significantly affects a child’s function, including abnormalities in gait and ambulation. The compensations that children undertake to overcome or adapt to these secondary manifestations are termed, tertiary manifestations . It is in addressing the secondary and tertiary manifestations where orthopedists take a lead role, with the goal of correcting lever arm dysfunction, preventing progression of deformity, and optimizing overall function. In a sense, the role of orthopedic surgeons is to maintain, improve, or optimize a child’s function and alter the natural history of the condition.
Introduction
Orthopedic management of children with cerebral palsy is a challenging task. The presentation is highly variable, ranging from those with mild clinical manifestations to those who are severely involved. The critical part in the initial assessment of children with cerebral palsy is the identification of risk factors for development of deformities so that attempts can be made to circumvent these events. This, in turn, maintains or improves a child’s overall function.
Cerebral palsy is characterized by an injury or insult to the immature brain. This may occur before, during, or up to 5 years after birth. The pathology in the brain is permanent and nonprogressive. It results in a wide variety of postural and movement disorders. Clinical manifestations are determined by the timing of the injury and whether they occur in the preterm (immature) or term (mature) infant. The underlying pathology can point to probable patterns of involvement. An immature or preterm infant with periventricular leukomalacia typically presents with spastic diplegia, whereas a child with periventricular hemorrhage is more likely to present with hemiplegia. Cerebellar involvement may present with hypotonia and ataxia. Occasionally, more than one lesion exists in the brain, resulting in a mixed presentation. A full-term child with watershed ischemia between the anterior and middle cerebral artery presents with quadriparesis whereas a focal ischemic injury in a full-term child presents with hemiparesis. Although the brain lesion is static, its manifestations are progressive. The primary manifestations of the neurologic insult include loss of selective motor control alteration in muscular balance and muscle tone abnormalities. This results in secondary manifestations of abnormal growth and development of the musculoskeletal system. It significantly affects a child’s function, including abnormalities in gait and ambulation. The compensations that children undertake to overcome or adapt to these secondary manifestations are termed, tertiary manifestations . It is in addressing the secondary and tertiary manifestations where orthopedists take a lead role, with the goal of correcting lever arm dysfunction, preventing progression of deformity, and optimizing overall function. In a sense, the role of orthopedic surgeons is to maintain, improve, or optimize a child’s function and alter the natural history of the condition.
Classification
Classification systems help define and quantify the underlying pathology. They help determine and guide clinicians toward the most appropriate treatment and aid in communication between clinicians. Several classification systems have been proposed, dating as far back as the 1800s. The most comprehensive of these is the classification proposed by Minear in 1956, which takes into consideration every aspect of a child, including physiologic, topographic, etiologic, traumatic, neuroanatomic, functional, and therapeutic involvement. Bax and colleagues proposed a simpler classification system based on motor abnormalities, associated impairments, anatomic and radiographic findings, and causation and timing. Functional classification schemes are also commonly used and these are based on a child’s overall functional capability. The Gross Motor Functional Classification System (GMFCS) is the most widely used functional scheme. It divides children into 5 groups based on the overall functional capability ( Table 1 ). The Functional Mobility Scale (FMS) describes motor function into 6 levels in 3 domains based on typical walking distance of 5, 50, or 500 m. This system is used to monitor change in motor function over time.
| GMFCS Level | Description |
|---|---|
| I | No functional impairment |
| II | Functional limitation, may need assistive device |
| III | Assistive device needed for ambulation |
| IV | Limited self-mobility, wheelchair often required |
| V | Wheelchair bound |
Assessment
Assessment of children with cerebral palsy centers on a complete history and physical evaluation. The history must include birth history and associated underlying medical conditions. The clinical evaluation should consist of a clinical evaluation of gait, both barefoot and with the use of orthotics, if any. Rotational profile should be checked to evaluate underlying torsional malalignment. Range of motion should be checked for the presence of any contractures. The specific underlying muscle tone is evaluated and recorded. A more detailed evaluation may include strength testing and an evaluation for selective motor control. Orthotics, assistive devices, and wheelchairs are evaluated to ensure that they fit properly.
Radiographs should be taken on the first orthopedic visit to establish a baseline; this is particularly true of the hips and pelvis. The severity of involvement and amount of deformity present dictate the frequency and need for sequential imaging studies on follow-up visits. Other advanced imaging techniques may be required prior to planning of reconstructive procedures.
A comprehensive gait analysis can be performed to obtain an objective assessment of the gait pattern that could be measured and quantified. This information can be further assessed to help in preoperative planning. It also provides a permanent record to compare the outcome of surgery. Studies have shown that gait analysis may aid and improve in surgical decision making in children with cerebral palsy.
Hips
The hips in children with cerebral palsy are normal at birth. The deformity occurs from loss of selective motor control and abnormalities in muscle tone and balance. Such deformities include coxa valga, femoral anteversion, and acetabular dysplasia. The muscular imbalance is typically due to strong hip flexors and adductors overpowering the hip extensors and abductors. The rate of hip subluxation in cerebral palsy has been reported as high as 75%. It is related to a child’s level of function. Lonstein and Beck found the rate of hip subluxation 11% in ambulators and 57% in nonambulators. Root reported the incidence of dislocation to be 8% and subluxation 38%. Soo and colleagues found no displacement in children who were GMFCS 1% and found 90% displacement in children who were GMFCS V. Increased femoral anteversion and coxa valga were also noted to be related to children’s GMFCS level; Robin and colleagues found femoral anteversion and neck shaft angles 30° and 135.9°, respectively, in those who were GMFCS I and 40° and 163°, respectively, in those who were GMFCS V.
Close surveillance of the hip joint is necessary. Identifying the hip at risk can lead to early and appropriate intervention to prevent the long-term sequelae of an untreated hip. Initial evaluation should include the hip range of motion; the presence or absence of contractures; pelvic obliquity; spinal deformity, if any; and femoral anteversion. Radiographic evaluation of the hip should quantify the amount of subluxation, if any. This is best assessed by the Reimer migration index (migration percentage) ( Fig. 1 ), which is the measurement of the width of the uncovered femoral head relative to the total width of the femoral head. In children with cerebral palsy, the migration index is believed within acceptable limits if it is below 30. An increasing migration index has been correlated to the increased risk for hip dislocation. Hagglund and colleagues reported that hips with a migration index greater than 40 had a high risk for dislocation and require treatment. Miller and Bagg reported that children with a migration index below 30 were at low risk for dislocation and those with a migration index of greater than 60% had complete dislocation. The acetabular index is used to evaluate and quantify acetabular dysplasia (see Fig. 1 ). Acetabular index of less than 20° is considered normal in adulthood. In children below 5 years of age, 25° is considered normal. An increased angle may denote the need to address the pelvic component of the deformity during surgical reconstruction. Radiographically, the amount of coxa valga may be assessed by measuring the neck shaft angle, which is typically increased. The radiographs must be taken with the hips in internal rotation to get an accurate measurement of the proximal femur. In more complex deformities, a CT scan may be useful in preoperative planning.
A severely involved child who is at an increased risk for the development of hip dysplasia and subsequent dislocation should be observed closely, with radiographs taken at regular intervals (approximately 6 months). In more functional ambulatory children, a baseline radiograph should be obtained and the need for follow-up radiographs should be at the discretion of the physician based on a child’s clinical evaluation. This may depend on whether there are initial concerns on the radiographs or if there are changes in the range of motion of the hip during regular evaluations. Nonoperative modalities should focus on maintaining hip range of motion, with or without formal physical therapy. Hip abduction bracing maybe attempted, but it may be difficult to maintain in the presence of a child’s underlying tone. Focal spasticity management may be performed to improve range of motion and allow children to tolerate bracing better. Short-term studies have shown initial benefit with the use of botulinum toxin, particularly in younger children. These findings have not been substantiated, however, by other studies. In a randomized study, Graham and colleagues reported a 1.4% decrease in the rate of hip displacement and they did not recommend botulinum toxin. In a long-term study, Willoughby and colleagues showed that botulinum toxin injection combined with abduction bracing did not significantly reduce the rate of hip reconstructive surgery or influence the development of the hips at skeletal maturity. The current recommendation is to get one anteroposterior pelvis radiograph between 2 to 4 years of age for GMFCS I and II (independent ambulators) and one radiograph every year until age 8 and then every 2 years until skeletal maturity for GMFCS III, IV, and V as long as the migration index is less than 30. If the migration index is more than 30, more frequent radiographs and possible intervention should be planned.
Operative modalities are intended to prevent progression of deformity or to address an established deformity, subluxation, and/or dislocation. Soft tissue procedures may be carried out to maintain and improve hip range of motion. Miller and colleagues performed iliopsoas and adductor lengthening in children with hip abduction of less than or equal to 30° and migration percentages of greater than or equal to 25%. At a mean follow-up of 39 months, 54% had good and 34% had fair outcome. The investigators concluded that early detection and intervention can lead to satisfactory outcome in 80% of children with spastic hips. This study, however, did not answer the question as to how many children would eventually require bony reconstruction. In a later long-term follow-up study, Presedo and colleagues reported that soft tissue releases were effective for prevention of hip dislocation. The best predictors of good outcome in their study were ambulatory status and migration percentage. In those children who develop progressive subluxation or dislocation, hip reconstruction may be required ( Fig. 2 ). During surgery, the deformity of the proximal femur and the acetabulum are assessed and addressed. In children with progressive subluxation or dislocation without significant acetabular dysplasia, a femoral varus derotation osteotomy combined with appropriate soft tissue procedures is often sufficient. In those with significant acetabular involvement, a pelvic osteotomy may be required. The osteotomy is performed to address the deficiency, which, in children with cerebral palsy, is more commonly posterior. Outcomes after operative intervention have been favorable. McNerney and colleagues reviewed 104 hips with a mean follow-up of 6.9 years. A total of 95% of the hips remained well reduced and there were no redislocations. Similarly, Miller and colleagues, in a review of 49 subluxated and 21 dislocated hips, reported 2 hip redislocations at a mean follow-up of 34 months; 82% of cases had complete pain relief. The current recommendations are as follows: children under the age of 8 years and with migration index between 30% and 60% should undergo adductor and iliopsoas lengthening, and children over the age of 8 years with migration percentage greater than 40% and all children with migration index greater than 60% should be recommended for hip reconstruction with femoral varus shortening osteotomy, pelvic osteotomy, and adductor lengthening.
In the skeletally mature hip, treatment is more challenging. Pelvic osteotomies, such as the Dega osteotomy or the Bernese periacetabular osteotomy, could be performed but the results might not be as optimal. Often the severity of deformity dictates the most appropriate course. The results of primary reconstruction in hips with chronic degenerative changes and significant deformity ( Fig. 3 ) may be dismal because pain may persist despite reconstruction. A fixed, painful, subluxated, or dislocated hip in a more mature patient with cerebral palsy often presents with a treatment conundrum. Typically, the hip shows denudation and loss of cartilage. Hip replacement can be performed and has the advantage of preserving hip motion. There are, however, substantial risks of hip dislocation, infection, and implant-related complications. Raphael and colleagues reported on 56 patients (59 hips) who underwent total hip arthroplasty. Patients were routinely placed in a unilateral hip spica postoperatively for 3 weeks. All patients had a minimum follow-up of 2 years (mean 9.7 years). There was complete pain relief in 48/59 (81%) hips and 52/59 (88%) returned to their prepain GMFCS level. Revision rate was 15%. There were 8 dislocations (14%). Two-year implant survivorship was 95%, and the10-year survivorship was 85%. Alternatively, Gabos and colleagues performed interpositional arthroplasty in 11 GMFCS V (non–weight-bearing) patients (14 hips) and achieved improvement in pain in 10 of 11 cases. Proximal femoral resection and interpositional arthroplasty were initially introduced by Castle and Schneider. McCarthy and colleagues revised the technique to perform the resection at the level of the ischial tuberosity; in their series, all but 1 patient achieved improvement in seating. The concerns related to proximal femoral resection are heterotopic ossification, increased time to pain relief, prolonged hospital stay, and migration of the proximal femur. To address the issue of heterotopic ossification, Egermann and colleagues used femoral head to cap the proximal femur and showed a decreased rate of heterotopic ossification. Another option in lieu of proximal femoral resection is a valgus osteotomy (McHale procedure). The goal of this procedure is to aim the femoral head away from the acetabulum while allowing for an indirect transfer of load. Several studies have shown an improvement in seating and pain relief. Leet and colleagues compared the results of proximal femoral resection with a valgus osteotomy with a mean follow-up of 3.4 years. Those treated with the McHale procedure had a shorter hospital stay and decreased proximal femoral migration. Both groups achieved improved seating and caretaker satisfaction.
Knees
Anterior knee pain may present as a significant issue in children with cerebral palsy. It is often related to the patellofemoral joint. The common causes of anterior knee pain include patella alta, patellar subluxation or dislocation, quadriceps weakness, angular deformity, and rotational malalignment. Senaran and colleagues looked at patients with anterior knee pain secondary to patellafemoral symptoms; in their study, the patients were classified based on patella alta, fracture of the inferior pole of the patella, and patellar subluxation or dislocation. The investigators advocated aggressive treatment to prevent future deterioration.
Knee flexion contractures frequently occur in children with cerebral palsy. It is more severe in nonambulatory children. In younger children (age <12 years) with less severe deformity (contractures <15°), serial casting has shown effective at achieving and maintain correction for at least 1 year. In more severe cases, hamstring release may be required to achieve adequate range of motion. In younger children with severe knee flexion deformity, guided growth in the form of an anterior hemiepiphysiodesis of the distal femur may be attempted. In ambulatory children with knee flexion contractures, treatment should be aimed at correction of the contracture and improvement in the gait pattern. Typically, these patients have a crouch gait pattern. Children with crouch gait ambulate with the hip, knee, and ankle in flexion. This gait pattern has been described as increased knee flexion in stance phase in spastic diplegics. The development of crouch gait has often been attributed to the natural progression of gait in ambulatory children with cerebral palsy. Muscle weakness has also been implicated in the development of progressive crouch gait after lengthening of the triceps surae. The cause of crouch is probably multifactorial and cannot be totally attributed to any single factor. In children with crouch gait, there is a failure of the plantar flexion–knee extension couple; hence, the knee maintains a flexed position with the ground reaction force falling behind the knee.
Several options exist to correct crouch gait. Initially, a ground reaction ankle foot orthosis may be used to aid in achieving knee extension. Surgical intervention for correction of crouch includes lengthening of the contracted muscle tendon units. Rethlefsen and colleagues showed, however, that repetitive hamstring lengthening does not result in long-term correction of crouch. A complete evaluation of children needs to be undertaken prior to surgical intervention. Correction of all underlying deformities and restoration of the knee extensor mechanism are essential in correction of crouch gait. Stout and colleagues showed that adequate correction can be achieved by addressing the knee flexion contracture through a distal femoral extension osteotomy (DFEO) and the patella alta with an advancement and transfer of the patellar tendon. In their series, children who underwent a combined DFEO with patellar tendon advancement did better than children who underwent DFEO alone or patellar tendon advancement alone. In a majority of cases of undergoing a DFEO, hamstring lengthening does not seem required. Correction of the other aspects of lower extremity malalignment, such as rotational malalignment (tibial torsion or femoral anteversion), planovalgus feet and muscle imbalance should be undertaken to restore and improve overall function. In a smaller series, Rodda and colleagues showed that the use of multilevel orthopedic surgery was effective in improving the knee extensor mechanism, relieving knee pain, and achieving improved function in children with crouch gait. Children should not be allowed to develop severe crouch to the point where they lose function and ambulatory potential and become wheelchair bound. Correction is indicated when the crouch increases or a child’s functional ability decreases.
Stiff knee gait results from increase spasticity of the rectus femoris muscle and is one of the common gait patterns seen in cerebral palsy. It interferes with the swing phase of gait by keeping the knee in extension, hence interfering with foot clearance. During the normal gait cycle, the rectus femoris is active during toe-off and inactive during midswing; it then reactivates during terminal swing and early stance to allow and prepare the limb for load acceptance. In stiff knee gait, the rectus femoris seems active during the entire swing phase of gait. Stiff knee gait is defined as decreased magnitude of peak knee flexion of less than 45°, decreased range of knee flexion, and delay in peak knee flexion. This may cause frequent tripping and falling. Other contributors to stiff knee gait include femoral torsional malalignment, poor push-off from the ankle, and weak hip flexor power.
Indications for treatment of stiff knee gait include decreased peak knee flexion, delay in time to peak knee flexion, and rectus femoris activity during swing phase of the gait. Transfer of the rectus femoris is the treatment of choice for stiff knee gait. The area or the site to where the rectus femoris is transferred does not seem to show any difference in the outcome of treatment when the area of the transfer is evaluated. It seems that the improvement in peak knee flexion is maintained long term. Although the results of simple release of rectus femoris in the treatment of stiff knee gait have not been good, there have been good results with a rectus femoris tendon resection of 4 to 6 cm ; rectus femoris transfer still seems superior to a release of the muscle in treatment of stiff knee gait. It seems that when the rectus femoris is firing out of phase, when it fires predominantly during swing as documented by electromyography, is when maximal benefit can be achieved with a rectus femoris transfer.
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