Myelodysplasia - the musculoskeletal problem: habilitation from infancy to adulthood.

KD Ryan, BS, PTm is Supervisor and Clinic Consultant, LDepartment of Physical Therapy and Occupational Therapy. Services, Children's Hospital, 300 Longwood Ave, Boston, MA 02115 Address all correspondence to Ms Ryan.

C Ploski, MS, PT, PCS, is Assistant Supervisor and Clinic Consultant, Department of Physical Therapy, and Occupational Therapy, Services, Children's Hospital.

JB Emans, MD, is Associate in Orthopaedic Surgery, Department of Orthopaedics, and Clinical Director, Myelodysplasia Clinic, Children's Hospital. He is also Assistant Clinical Professor, Department of Orthopedic Surgery, Harvard University, Cambridge, MA 02138.

Myelodysplasia, or myelomeningocele, is a complex congenital disorder that primarily affects the nervous system and secondarily affects the musculoskeletal and urologic systems (Tab. 1). The myelodysplastic defect involves a failure of the fusion of the caudal end of the neural tube or rupture of the nearly closed neural tube, occurring early in embryonic development before the 28th day of gestation. The etiology is unknown but is believed to be multifactorial and includes genetic and environmental influences.(1)

The incidence of myelodysplasia varies in different parts of the world but is generally 1 per 1,000 births.(2) A slightly higher incidence is found in individuals of northern Europe origin. There is a 1% to 2% greater chance of a child being born with mmyelodyplasia if a sibling is already affected.(3)

Prenatal screening can lead to early detection of the defect. Elevated levels of alpha-fetoprotein in the maternal serum after the 16th week of gestation may be indicative of a neural tube defect.(4) Ultrasound testing per formed between the 16th and 24th weeks of gestation may decrease the need for a subsequent amniocentesis., Amniocentesis performed at this time detects almost all open myelomeningoceles but not closed (skin-covered) myeloceles.(6) Early detection may present a difficult decision for the parents, because termination of the pregnancy is the only way to prevent the defect. Prior knowledge, however, can prepare parents for the need for a cesarean birth and immediate postnatal care.

Most infants born with myelodysplasia are treated aggressively with immediate closure and shunt insertion to manage hydrocephalus,(7) but this approach has not always been followed. Lorber,(8) in 1971, found that even those children who were treated had considerable problems with selfesteem and the attainment of functional independence. He recommended "selective treatment" based on four criteria identified at birth: the degree of paralysis, the degree of increased head circumference, the presence of kyphosis and other associated congenital anomalies, and birth injuries. Gross and colleagues,(9) using criteria similar to the criteria used by Lorber, as recently as 1983 also suggested that treatment be withheld for some infants. Most authorities today, however, agree that children with myelodysplasia should be treated aggressively to minimize neurologic deficits. in recent years, improved closure techniques and other medical advances and increased societal acceptance of the disability have contributed to a better quality of life for these individuals. (10)

Optimal management of the child with myelodysplasia occurs in a clinical setting with a team of knowledgeable professionals.(11) The treatment team should include a neurosurgeon, orthopedic surgeon, urologist, pediatrician, nurse, physical therapist, occupational therapist, social worker, and orthotist. We believe the availability of a nutritionist, speech and language pathologist, and psychologist is also essential for comprehensive management.

The purpose of this article is to review current physical therapy and orthopedic management of children with myelodysplasia from infancy through adolescence. A philosophy and controversies of care will he addressed.

Associated Problems

Neurologic Deficits

The primary neurologic problems in persons with myelodysplasia are the variable motor and sensory deficits, which will be discussed in detail in the "Physical Therapy and Orthopedic Management" section. Associated central nervous system problems are often present.

Hydrocephalus. Evidence of hydrocephalus is present in 80% or more of infants with myelodysplasia.(12) Clinical symptoms are manifested by bulging fontanel, increasing head circumference, downward deviation of the eyes ("sunset eyes"), irritability, projectile vomiting, and seizures.

Hydrocephalus is managed by the insertion of a shunt, most commonly a ventriculoperitoneal shunt.(13) Shunt insertion may be performed when the defect is closed or later when the symptoms of hydrocephalus are apparent. Revisions are necessary if the shunt tubing becomes occluded, disconnected, or infected.

Some studies(14-15) have shown that children with hydrocephalus may have reduced intelligence and perceptual-motor impairments. More recently, however, Mapsstone and colleagues(16) demonstrated that intellectual function is also affected by complications from shunting and by other central nervous system anomalies. Advances in shunt-placement techniques and infection control have improved the outcome. Perceptual-motor impairment affects school performance. Evaluation for perceptual-motor dysfunction is frequently handled by an occupational therapist.

Arnold-Chiari malformation. In the Arnold-Chiari defect, the lower brain stem and cerebellum, including the fourth ventricle, herniate through the foramen magnum into the spinal canal. The fourth ventricle may become obstructed and the flow of cerebrospinal fluid impeded, resulting in hydrocephalus.(17) Virtually every child with myelomeningocele has the malformation, and its presence and severity are confirmed by magnetic resonance imaging (MRI), as well as the presence of clinical manifestations.(18) Clinical signs include respiratory symptoms, such as apnea, stridor, vocal cord paralysis, and upper-extremity weakness or spasticity. A shunt insertion or revision is the usual management technique, but severe cases occasionally require cervical laminectomy and posterior decompression.(19)

Syringomyelia and hydromyelia. Syringomvelia is present if there is a dilatation of the central canal of the spinal cord, resulting in an elongated cavity (syrinx) within the spinal cord filled with cerebrospinal fluid.(20) Hydromyelia or syringohydromvelia are other terms commonly used for this condition. Symptoms such as the development of scoliosis, upperextremity weakness, or sensory changes may occur if the syndrome progresses. The treatment is complicated and varies according to the etiology of the syrinx.(21,22)

Tethered spinal cord. Progressive neurologic dysfunction may indicate tethering of the conus medullaris and lower spinal cord roots.(23) Tethering results from scar formation and binding of the spinal cord tissue to the bony column at the site of the initial repair, with subsequent inhibition of normal spinal cord movement with growth or activity. A clinical diagnosis is made based on deterioration of urologic function, progressive orthopedic deformities, changes in motor status, back or leg pain, or deterioration in gait. Usually, the change in motor function entails loss of muscle strength, although muscle activity not previously seen and not under voluntary control may also appear. Surgical untethering is performed to halt the progression of the symptoms, but is not always successful.(24)Existing deformities or problems may persist and require orthopedic intervention.

Musculoskeletal Problems

A variety of bone and joint deformities that affect function are encountered in children with myelodysplasia. Affected extremities usually exhibit muscle atrophy and osteopenia. Together, osteopenia, limited joint proprioception, and resistant contractures make fractures a frequent occurrence.(25,26) Some deformities are congenital, hut the majority are acquired through growth and abnormal forces introduced by muscle imbalances, static positioning and gravity, and weight bearing on joints with insufficient muscular support. The source of the deformity should be determined before intervention, because the success of treatment can be hindered by a changing neurological picture, such as the progressive deformities seen with a tethered spinal cord.

Lower extremities. Hip subluxation and dislocation are common.(27) They may be present at birth or develop with growth because of the unbalanced action of the hip flexors and adductors. Hip flexion contractures also occur frequently.

Knee flexion contractures occur in children with high neurosegmental levels of involvement,(28) and such contractures may impede the use of braces or a standing frame. Progressive knee flexion deformities may also accompany spasticity (hypertonia) resulting from a tethered spinal cord. Ambulatory individuals with strong ankle dorsiflexors but weak gastrocnemius muscle function may develop knee flexion deformities from a crouched stance. Knee hyperextension deformities and rectus femoris muscle contracture can result from strong quadriceps femoris muscle function unopposed by hamstring muscle activity. Hypertrophy of the sartorius muscle secondary to overuse can be accompanied by a functionalty insignificant snapping of the muscle as it glides across the medial knee structures. Patellofemoral overuse syndromes are common in community ambulators with low-lumbar neurosegmental levels of involvement, who rely heavily on their quadriceps femoris muscles, particularly if a knee flexion contracture is present.

Congenital foot deformities (eg, clubfoot, vertical talus) are most common in children with mid-lumbar neurosegmental levels of involvement. Acquired foot deformities such as talipes calcaneus, talipes cavus, and talipes planovalgus, which develop from unbalanced muscle forces and unsupported weight bearing, occur most commonly in children with lower neurosegmental levels of involvement. As foot sensation is often incomplete, neurotrophic ulceration can become a problem and may interfere with ambulation.

Spinal deformities. Scoliosis and kyphosis have many etiologies in children with myelodysplasia. in addition to abnormal skin covering and displacement of neural elements, the bony spine is abnormal. The stabilizing effect of the paraspinal muscles is often lost, because the muscles are displaced laterally or may be denervated. In individuals with kyphotic deformities, the muscles may be anterior as well as lateral to the spinal column. Spinal deformities may result from unbalanced growth attributable to congenital abnormalities (congenital scoliosis or kyphosis), from abnormal stresses of pelvic obliquity or hip contracture, or from paralytic collapse. Significant scoliosis in a structurally normal part of the spine or a rapid increase in spinal deformity may result from spinal cord tethering or other neurologic problems.(24)

Bowel and Bladder Problems

The child with myelomeningocele many experience problems with bladder control, which may adversely affect renal function.(29) Clean, intermittent catheterization, in combination with pharmacologic agents, has enabled most children to become continent.(29) Urodynamic studies are performed in the neonatal period and at regular intervals as the child matures. The results provide baseline information that is useful in predicting future function and in detecting changes that may indicate neurological deterioration.(30)

Fecal incontinence affects the child's self-esteem and social acceptance.(31) Management includes a combination of regular toileting, diet, medication, biofeedback, and behavior modification.(32)

Physical Therapy Assessment

A comprehensive evaluation includes testing range of motion (ROM), posture, sensation, muscle strength, developmental reflexes, motor development, and functional status. Qualitative and quantitative assessments are used to assess motor development, identify strengths and weaknesses, and provide a basis for intervention. Abnormal or immature patterns of movement and any asymmetries should also be documented. Both upper and lower extremities are tested because associated central nervous system problems can affect the upper extremity and affect mobilility. (18,20,24,33-36) Assessments are repeated at intervals ranging from 1 month to 1 year, according to the age arid needs of the child. Results of sequential examinations allow comparisons to determine the rate of progress, to detect changes that may be indicative of deterioration, and to judge the effectiveness of interventiouns. The findings within each test area should be interpreted separately as well as jointly when impressions of status, prognosis, and physical therapy intervention are formed.

Range of Motion

Standard test proceedures have been established for measurement of joint ROM(37,38) Modifications are necessary in the neonate who may have position restrictions (Fig. 1) or for any child who is unable to assume test positions because of deformity or discomfort.

The interpretation of the results of the joint ROM measurement should always be based on the individual's age, muscle strength, and potential functional status. For example, in neonates and young infants, limitations of hip and knee extension and hip adduction are normal and do not necessarily indicate a problem.39 If there is an accompanying muscle imbalance or the limitations persist over time, however, the findings should be considered abnormal.

Posture

Alignment of the trunk and extremities should be assessed through palpation of bony landmarks and observation. Asymmetries and deviations from normal are recorded. Real and apparent leg-length discrepancies may be indicative of a dislocated hip, pelvic obliquity, or scoliosis. Abnormal findings, particularly if new or progressive, warrant orthopedic assessment.

Sensation

The results of sensory testing establish the sensory level and, more importantly, identify areas that may be at risk for skin breakdown. The presence of any joint or postural deformities further increases the risk for skin breakdown in insensate areas because of unequal weight bearing.

The behavioral state of the infant affects the sensory testing, which should normally be performed when the infant is quiet. The infant's medical status and the effects of any medications must be considered. Reactions to appropriate stimuli that may indicate intact sensation include grimacing, crying, or withdrawal from the stimulus. We believe sensory testing becomes more accurate and precise at later ages. Light touch, position sense, temperature, and two-point discrimination, in addition to pain, can be assessed in the older child.

Strength

The results of the initial and subsequent muscle examinations are used to identify the affected neurosegmental levels and to predict the functional outcome (Tab. 2).(40-43) Realistic interventions are determined based on the upper- and lower-extremity muscle strength in combination with the child's developmental level.

The procedure and grading for muscle testing must be modified in infants and young children according to their age and developmental level, as well as their medical status.(44) Grades that have resistance as a criterion, Fair plus or above,(46) may be difficult to assign, because the infant or young child is unable to cooperate or to understand the concept of resistance. If an infant resists passive movement, however, the muscle strength may be graded as at least Fair plus. In a young child, the ability to lift body weight in an activity such as bridging can be used to determine whether the strength of the gluteus maximus muscle is above the Fair level.

The initial muscle examination is usually performed following closure of the defect, once the infant is medically stable. The infant is usually restricted to the prone or side-lying position in order to allow the back to heal. if hydrocephalus is present, there may be further restrictions on upright positioning. Once the positioning restrictions are discontinued, the infant's strength can be assessed in the supine and upright positions.

The infant should be awake and alert, which is often just prior to feeding. Resting posture is observed as well as spontaneous movement. Muscles must be palpated for contraction in order to differentiate between the activity of individual muscles and muscle groups. Tactile stimuli in the area of the deficits as well as at sites innervated by nerves from levels above the spinal defect are used to elicit movement. Positioning a joint or joints in extreme ROM (eg, maximum hip and knee flexion) may stimulate the infant to contract the antagonist. Responses such as the plantar-grasp or equilibrium reactions may also be used to elicit muscle contractions. The presence of muscle activity with reflex stimulation only should be documented, but does not necessarily indicate voluntary control.

Modifications of muscle testing procedures are also necessary for testing the older infant and young child. Developmental activities, such as rolling to elicit hip flexion or pulling to a standing position to determine quadriceps femoris muscle function, may be used. The use of traditional techniques of muscle testing depends on the child's ability to cooperate and follow directions, but, in our experience, these techniques can usually be used by the age of 4 years. Hand-held dynamometers have also been used in pediatric populations to assess muscle strength.(47) Strength assessments should be performed every 6 months in the growing child and yearly in the adolescent to monitor for changes.

Developmental Reflexes and Postural Reactions

Procedures have been established for testing developmental reflexes and postural reactions.(48,49) The presence or absence of certain responses may have a direct influence on gross motor skills(50) and, therefore, treatment decisions. For example, we believe the attainment of independent upright stance cannot be achieved without effective righting and equilibrium reactions or in the presence of certain primitive reflexes. The physical therapy program often includes techniques to facilitate more mature reactions while inhibiting the primitive responses.

Development and Function

The rate of development of motor skills is slower in children with myelodysplasia than in children without myelodysplasia and is related to the neurosegmental level that is affected.(51) Medical problems, such as shunt infections, may result in regression or delay of motor development.(52)

Developmental testing is frequently used for the infant and young child. Developmental tests that are standardized (ie, norm or criterion referenced) provide quantitative, objective information about motor abilities.(53-55) Scores from standardized tests document the degree of developmental delay and may be required in order to justify the need for intervention. Modifications may be necessary when administering and scoring test items, particularly if the child uses adaptive equipment. Statements regarding the influence of factors such as the child's motor level and associated neurologic or orthopedic problems should be included in the interpretation of the overall scores.

The achievement of specific developmental milestones has implications for decisions regarding orthopedic intervention. For example, if an infant has not achieved adequate sitting balance by the age of 10 months because of trunk instability, a spinal orthosis may be a treatment option. Conversely, if an infant has not developed good head control, surgical intervention to decrease lower-extremity contractures and to allow use of an ambulatory device may not be appropriate.

Functional assessments are used to determine the readiness and need for adaptive equipment such as bracing. These assessments are also used to determine the older child's ability to function in various environments (eg, school, home). Functional assessments include evaluations of gross motor abilities, mobility, and self-care activities. Assessment of motor abilities includes a description of the child's ability to move into, within, and out of various positions and to maintain those positions, as well as a description of the child's ability to function within each position. Assessment of mobility includes an evaluation of gait, wheelchair activities, and transfers. if the child is ambulatory, the type of gait (eg, reciprocal, swing-through), gait deviations, use of assistive devices, and level of ambulation(56) (eg, household, community ambulator) should be described. The ability and ease with which the child ambulates or maneuvers a wheelchair on various terrains and levels and the child's endurance are also assessed. Activities of daily living include hygiene activities (eg, toileting, bathing, skin care), feeding, and dressing. The child's level of independence and need for adaptive equipment should be noted.

Physical Therapy and Orthopedic Management

The overall goal of orthopedic and physical therapy management is the habilitation of the child by maximizing the child's function, independence, and self-esteem while minimizing family stress. Specific goals for each child are formulated, depending on the results of the assessment. Conservative or nonsurgical treatments include physical therapy, casting, bracing, and splinting. We believe that carefully planned surgical interventions may save unnecessary casting or bracing and may help foster independence.

The Neonate

Physical therapy management of the neonate is usually initiated in the period immediately following closure of the back defect. General objectives include increasing ROM and active movement and promoting the achievement of developmental milestones.

Early treatment is limited by the infant's medical status and position restrictions, which are dependent on the type of closure, rate of healing, postoperative complications, the management of hydrocephalus, and the physician's judgment. Prone and sidelying positioning are usually allowed before supine positioning. When the infant can be positioned supine and upright, the developmental program can he expanded.

We believe that appropriate tactile, visual, and auditory stimuli should be introduced to facilitate movement and development. Passive exercises, facilitation of active movement, and positioning techniques are used to oppose any contractures and muscle imbalances.

Parent education is a major focus. The role of and rationale for physical therapy are explained. Parents are instructed in a home program that includes exercises, positioning and handling techniques, and appropriate developmental activities. Skin-care instructions are also given, and standard child care equipment is modified, if needed. Follow-up visits are arranged prior to discharge, and referrals are made to local treatment programs.

The infant

During infancy, attainment of age-appropriate developmental motor milestones is emphasized. Achievement of upright stance is the overall goal. Activities are incorporated into the program to facilitate head and trunk control in the developmental positions. Prone activities are used to increase upper-extremity strength. Early mobility through rolling, belly crawling, and quadrupedal creeping is encouraged and facilitated, because these achievements provide the foundation for future motor progress. Postural and balance reactions are facilitated, because they are prerequisites for independent standing. Fighting and equilibrium reactions will also help strengthen the neck and trunk musculature and promote independent sitting. Modifications in seating may be needed if the child has a severe kyphosis or lacks appropriate head and trunk control.

The Preschool-aged Child

Physical therapy has an active role at this time, particularly in assisting the child in attaining some form of independent mobility. As the child begins to pull to a standing position, orthopedic intervention may be needed to achieve upright stance. Intervention may include bracing, casting, bony or soft tissue procedures around the hip, and release of contractures that interfere with function. Treatment of foot deformities must be individualized. In our experience, in spite of casting and stretching, most severe foot deformities will require surgery. A plantigrade, supple, braceable foot is the goal.

General principles of surgical treatment include correction of bony deformity and balancing of muscle forces. With the use of internal fixation, postoperative immobilization is kept to a minimum to diminish osteopenia and subsequent fractures.(57)

In our view, as many procedures as possible should be performed during the same hospitalization or same operative session. We attempt to complete all orthopedic surgeries prior to age 5 years, in order to minimize interference with schooling.

Orthopedic management of hip deformities. Treatment of hip dislocation in children with myelodysplasia is individualized and differs greatly from the management of congenital hip dislocation in children without myelodysplasia or the management of paralytic dislocation in children with spastic cerebral palsy. Hip subluxation in myelodysplasia, unlike that in spastic cerebral palsy is generally not associated with pain. The presence of dislocation or subluxation noted on a radiograph is less important than maintenance of hip joint motion and avoidance of joint contractures. Treatment generally depends on the child's ambulatory potential, which correlates best to the neurosegmental level of involvement.(56,58,59)

Hip subluxation occurs infrequently with lumbosacral neurosegmental levels of involvement, but is usually treated aggressively because of the excellent ambulatory potential of these children. in individuals with thoracic or upper-lumbar neurosegmental levels of involvement, community ambulation is not anticipated beyond childhood. Because little demand will be placed on the hips, contracture releases are performed as needed to maintain ROM. We believe surgical reductions, osteotomies, and muscle transfers are generally not indicated, because the benefits do not outweigh the risks of postoperative stiffness or heterotopic ossification. A severe postoperative hip contracture may prevent the patient from assuming either a sitting or standing position. We also believe a mobile, dislocated hip is preferable to a stiff, reduced hip, particularly in the nonambulatory patient.

There is a relatively high incidence of hip subluxation in children with mid-to low-lumbar neurosegmental levels of involvement.(27) In these individuals, the presence of quadriceps femoris muscle function makes community ambulation a possibility. Unopposed hip adductors and flexors tend to produce progressive subluxation and eventual dislocation. Management of subluxations in these individuals is an area of considerable controversy. In the infant, abduction splinting and stretching will help maintain ROM and may facilitate acetabular and femoral development. As subluxation and dislocation gradually develop, a decision must be made as to whether to treat the hip dislocation. if the child has little ambulatory potential because of neurologic problems, reduction is not indicated and muscle releases are performed as needed to maintain ROM. If there is good ambulatory potential, as indicated by the presence of a strong quadriceps femoris musculature, and in the absence of other complicating factors, then the child is a potential candidate for surgical treatment of the hip subluxation.

Proponents of hip reduction and muscle transfer argue that optimal ROM is achieved by hip reduction.(61,64) Better posture and gait mechanics may result from keeping the hips reduced and from associated muscle transfers. Opponents of hip reduction believe that operative reduction exposes the child to the risk of hip stiffness without functional benefit and that soft tissue releases alone are sufficient to maintain ROM and ambulatory ability.(65-68)

Studies(56,65,68) have shown no correlation between the level of ambulation and the status of the hips in children with mid-lumbar neurosegmental levels of involvement. Because other factors, such as severe hydrocephalus, Arnold-Chiari malformation, obesity, motivation, and contractures, also influence ambulation, the results of these studies remain somewhat inconclusive.

If the decision is made to relocate the hips, open reduction with capsulorrhaphy is generally required.(60) Pelvic or femoral osteotomy, or both, may also he necessary. Because the iliopsoas and adductor muscle groups are largely unopposed in these children, some attempt is usually made to balance the musculature, or dislocation will gradually recur. Most procedures include adductor release or posterior transfer of the adductor origin.(69) Lateral transfer of the external oblique muscle to the greater trochanter(70) to provide stabilizing force is now widely used. Another approach consists of lateral transfer of the iliopsoas muscle, through a hole created in the wing of the ilium, to the greater trochanter.(71) This transfer alleviates the deforming force of the iliopsoas muscle and provides a tenodesis or active hip abduction. Both approaches have their advocates. Many feel the external oblique muscle transfer allows better ambulation and does not diminish the patient's ability to flex the hips and climb stairs (RE Lindseth, L Dias; personal communication), although follow-up studies of iliopsoas muscle transfers do not show impairment in climbing stairs.63 Others feel iliopsoas muscle transfer is more likely to ensure maintenance of reduction. Tailoring treatment to the individual child is crucial and must be based on a realistic assessment walking potential.

Orthotic management. Some degree of contracture may be accommodated by orthoses. Surgical release, however, is indicated to facilitate orthotic management if hip flexion contractures are greater than 30 degrees, knee flexion contractures are greater than 20 degrees, and plantar-flexion deformities are greater than 10 degrees.

We believe all children, except those with severe central nervous system involvement, should be given the opportunity to be upright, regardless of their functional prognosis. This philosophy is based on the premise that weight bearing increases bone density,(72) helps to maintain urinary tract function, and develops self-esteem.

Either a parapodium or a standing frame (Fig. 2) can be used as the first orthosis for the child with a neurosegmental level of L-3 or above to achieve upright stance and early mobility. The swivel walker, parapodium, and standing frame may also be used for long-term mobility. We have found, however, that few children learn to release the joints of the parapodium. We therefore prefer the standing frame, which is less expensive and easier to apply.

Time spent in the standing frame depends on the child's tolerance and skin integrity. Once the desire to move in the frame is evident, consideration is given to orthotic devices that allow more functional ambulation. The overall goal is to provide maximum mobility with the minimum amount of bracing.(73)

The reciprocating gait orthosis (RGO) is used for children with thoracic and high-lumbar neurosegmental levels of involvement as young as 18 months of age. Some practitioners prefer to wait until the children are 30 to 36 months of age before prescribing the RGO (see article by Knutson and Clark in this issue). Individuals using the RGO are more likely to achieve household ambulation and remain functional longer than if they used other braces.(74,75)

General guidelines have been established for determining appropriate orthoses for functional mobility (see article by Knutson and Clark in this issue). Hip-knee-ankle-foot orthoses (HKAFOS), knee-ankle-foot orthoses (Kafos), ankle-foot orthoses (AFOs), and foot orthoses (FOs) are prescribed, depending on the child's neurosegmental level of involvement.

The pelvic band of the HKAFO assists in the control of hip abduction, adduction, and rotation during gait. If placement of the lower extremity is not a problem, a KAFO may be used for individuals with little or no quadriceps femoris muscle strength. An AFO or FO is indicated if foot and ankle support are needed.

Functional mobility. Gait training is initiated in the parallel bars. Activities to develop balance and the ability to weight shift are utilized. Progression to either an anterior- or reverse-facing (posterior) walker is made once independent ambulation in the parallel bars is achieved. We prefer the reverse-facing walker whenever possible, as it promotes better postural some attempt is usually made to balance the musculature, or dislocation will gradually recur. Most procedures include adductor release or posterior transfer of the adductor origin.(69) Lateral transfer of the external oblique muscle to the greater trochanter(70) to provide stabilizing force is now widely used. Another approach consists of lateral transfer of the iliopsoas muscle, through a hole created in the wing of the ilium, to the greater trochanter.(71) This transfer alleviates the deforming force of the iliopsoas muscle and provides a tenodesis or active hip abduction. Both approaches have their advocates. Many feel the external oblique muscle transfer allows better ambulation and does not diminish the patient's ability to flex the hips and climb stairs (RE Lindseth, L Dias; personal communication), although follow-up studies of iliopsoas muscle transfers do not show impairment in climbing stairs.(63) Others feel iliopsoas muscle transfer is more likely to ensure maintenance of reduction. Tailoring treatment to the individual child is crucial and must be based on a realistic assessment walking potential.

Orthotic management. Some degree of contracture may be accommodated by orthoses. Surgical release, however, is indicated to facilitate orthotic management if hip flexion contractures are greater than 30 degrees, knee flexion contractures are greater than 20 degrees, and plantar-flexion deformities are greater than 10 degrees.

We believe all children, except those with severe central nervous system involvement, should be given the opportunity to be upright, regardless of their functional prognosis. This philosophy is based on the premise that weight bearing increases bone density,(72) helps to maintain urinary tract function, and develops self-esteem.

Either a parapodium or a standing frame (Fig. 2) can be used as the first orthosis for the child with a neurosegmental level of L-3 or above to achieve upright stance and early mobility. The swivel walker, parapodium, and standing frame may also be used for long-term mobility. We have found, however, that few children learn to release the joints of the parapodium. We therefore prefer the standing frame, which is less expensive and easier to apply.

Time spent in the standing frame depends on the child's tolerance and skin integrity. Once the desire to move in the frame is evident, consideration is given to orthotic devices that allow more functional ambulation. The overall goal is to provide maximum mobility with the minimum amount of bracing.(73)

The reciprocating gait orthosis (RGO) is used for children with thoracic and high-lumbar neurosegmental levels of involvement as young as 18 months of age. Some practitioners prefer to wait until the children are 30 to 36 months of age before prescribing the RGO (see article by Knutson and Clark in this issue). Individuals using the RGO are more likely to achieve household ambulation and remain functional longer than if they used other braces.(74,75)

General guidelines have been established for determining appropriate orthoses for functional mobility (see article by Knutson and Clark in this issue). Hip-knee-ankle-foot orthoses (HKAFOs), knee-ankle-foot orthoses (KAFOs), ankle-foot orthoses (AFOs), and foot orthoses (FOs) are prescribed, depending on the child's neurosegmental level of involvement.

The pelvic band of the HKAFO assists in the control of hip abduction, adduction, and rotation during gait. If placement of the lower extremity is not a problem, a KAFO may be used for individuals with little or no quadriceps femoris muscle strength. An AFO or FO is indicated if foot and ankle support are needed.

Functional mobility. Gait training is initiated in the parallel bars. Activities to develop balance and the ability to weight shift are utilized. Progression to either an anterior- or reverse-facing (posterior) walker is made once independent ambulation in the parallel bars is achieved. We prefer the reverse-facing walker whenever possible, as it promotes better postural alignment than does the anterior-facing walker.(76) If a reverse-facing walker is selected for a child, the depth should be sufficient to allow posterior clearance for orthoses that have pelvic components. once the child is able to maintain standing balance and ambulate confidently with the walker without assistance, forearm crutches may be introduced.

Independent mobility by walking is the goal during early childhood. In our experience, however, many children will require a wheelchair to improve access to the environment, despite optimal bracing and gait training (Fig. 3). Considerable controversy exists surrounding the timing of the introduction of a wheelchair for children who are unlikely to achieve independent community ambulation. The proponents of early wheelchair introduction have argued That early training will maximize eventual wheelchair skills. The opposing view is that early introduction limits the child's ambulatory potential. Mazur and colleagues, in a recent comparative study of two groups of patients, found that the timing of the introduction made no difference in the ultimate level of wheelchair skill or ambulation.

We introduce the wheelchair as early as 18 months of age if it is apparent that this device will enhance mobility and independence. Early introduction usually enables children to keep up with their peers. in our experience, early wheelchair use has not led to the cessation of ambulation, even in marginal ambulators. Rather, the boost in self-confidence and independence that may accompany wheelchair use seems to increase their activity level and overall mobility. We view the wheelchair as an aid to mobility and do not believe that its use represents a "failure" of management.

Orthopedic management of kyphosis. Seating arrangements and bracing will be complicated by the presence of a kyphotic deformity. Some children, generally those with low-thoracic or high-lumbar level of paralysis, have a severe congenital kyphosis or a collapsing thoracolumbar kyphosis. These deformities normally increase with growth and commonly result in functional and cosmetic difficulties.

Chronic skin breakdown over the kyphotic area may result from pressure against the back of a chair, friction during wheelchair use, or irritation from pelvic bands. Compensatory thoracic lordosis may develop above the thoracolumbar kyphosis and can cause respiratory difficulties. Care of abdominal ileal loops or colostomies becomes difficult when the child is collapsed forward into kyphosis and the contour of the abdomen is distorted. The child's body image may be severely altered by the trunk distortion accompanying severe kyphosis.

Brace or cast treatment of congenital kyphosis or collapsing kyphosis rarely stops progression of the deformity and frequently contributes to skin breakdown. Orthoses, nevertheless, can improve sitting posture and balance, particularly in individuals with flexible collapsing kyphosis.

The most common surgical procedure when kyphosis is present in individuals with paraplegia is excision of the deformed spinal segment (kyphectomy) and the nonfunctional cord at the level of the kyphosis.(78) The remaining relatively straight upper- and lower-spine segments are united by instrumentation and fusion. This procedure effectively removes the kyphosis, but results in a shorter-thannormal trunk. Growth over the fused spinal segment is halted; hence, this procedure is delayed, if possible, until late childhood. Care must be taken when excising the nonfunctional cord to ensure that bladder function will not be adversely affected, because some individuals have a functioning sacral cord in spite of no lower-extremity motor function.

The School-aged Child

Because most children with myelodysplasia are mainstreamed in public or private schools,(79) physical therapy programs during childhood are based in the school. Services may be direct, indirect, or consultative, but the overall goal of functional independence remains unchanged. Activities of daily living, such as dressing and brace management, as well as continued alignment than does the anterior-facing walker.(76) If a reverse-facing walker is selected for a child, the depth should be sufficient to allow posterior clearance for orthoses that have pelvic components. once the child is able to maintain standing balance and ambulate confidently with the walker without assistance, forearm crutches may be introduced.

Independent mobility by walking is the goal during early childhood. in our experience, however, many children will require a wheelchair to improve access to the environment, despite optimal bracing and gait training (Fig. 3). Considerable controversy exists surrounding the timing of the introduction of a wheelchair for children who are unlikely to achieve independent community ambulation. The proponents of early wheelchair introduction have argued that early training will maximize eventual wheelchair skills. The opposing view is that early introduction limits the child's ambulatory potential. Mazur and colleagues,in a recent comparative study of two groups of patients, found that the timing of the introduction made no difference in the ultimate level of wheelchair skill or ambulation.

We introduce the wheelchair as early as 18 months of age if it is apparent that this device will enhance mobility and independence. Early introduction usually enables children to keep up with their peers. In our experience, early wheelchair use has not led to the cessation of ambulation, even in marginal ambulators. Rather, the boost in self-confidence and independence that may accompany wheelchair use seems to increase their activity level and overall mobility. We view the wheelchair as an aid to mobility and do not believe that its use represents a "failure" of management.

Orthopedic management of kyphosis. Seating arrangements and bracing will be complicated by the presence of a kyphotic deformity. Some children, generally those with low-thoracic or high-lumbar level of paralysis, have a severe congenital kyphosis or a collapsing thoracolumbar kyphosis. These deformities normally increase with growth and commonly result in functional and cosmetic difficulties.

Chronic skin breakdown over the kyphotic area may result from pressure against the back of a chair, friction during wheelchair use, or irritation from pelvic bands. Compensatory thoracic lordosis may develop above the thoracolumbar kyphosis and can cause respiratory difficulties. Care of abdominal ileal loops or colostomies becomes difficult when the child is collapsed forward into kyphosis and the contour of the abdomen is distorted. The child's body image may be severely altered by the trunk distortion accompanying severe kyphosis.

Brace or cast treatment of congenital kyphosis or collapsing kyphosis rarely stops progression of the deformity and frequently contributes to skin breakdown. Orthoses, nevertheless, can improve sitting posture and balance, particularly in individuals with flexible collapsing kyphosis.

The most common surgical procedure when kyphosis is present in individuals with paraplegia is excision of the deformed spinal segment (kyphectomy) and the nonfunctional cord at the level of the kyphosis.(78) The remaining relatively straight upper- and lower-spine segments are united by instrumentation and fusion. This procedure effectively removes the kyphosis, but results in a shorter-than-normal trunk. Growth over the fused spinal segment is halted; hence, this procedure is delayed, if possible, until late childhood. Care must be taken when excising the nonfunctional cord to ensure that bladder function will not be adversely affected, because some individuals have a functioning sacral cord in spite of no lower-extremity motor function.

The School-aged Child

Because most children with myelodysplasia are mainstreamed in public or private schools,(79) physical therapy programs during childhood are based in the school. Services may be direct, indirect, or consultative, but the overall goal of functional independence remains unchanged. Activities of daily living, such as dressing and brace management, as well as continued work on mobility skills, are addressed during the school years.

Orthopedic management of scoliosis. late childhood and early adolescence, the effects of progressive scoliosis may become apparent. Nonambulatory individuals with severe scoliosis sit with their trunk out of balance in relation to their pelvis. They may require the use of one or both upper extremities to maintain their sitting balance and may need extensive adaptive seating. Pressure from unequal weight bearing during sitting increases the likelihood of ulceration. In our experience, bracing has limited usefulness in preventing progressive scoliosis and the need for eventual surgery. For the child who has difficulty with trunk control, however, bracing may help to improve balance and therefore upper-extremity function.

Surgery for scoliosis is complicated by the presence of rigid bony deformities, deficient skin coverage, soft bone, and lack of posterior bony elements. Combined anterior and posterior fusion and segmental instrumentation has made surgical correction, instrumentation, and fusion more predictable.(80) Infection, loss of correction, neurologic injury, and failure of fusion remain common complications. Stronger segmental instrumentation has improved correction and often allowed the child to be brace or cast free in the postoperative period.

Correction of scoliosis in the individual who is nonambulatory equalizes weight bearing on bony areas for sitting and minimizes the likelihood of ulceration. Care must be taken to maintain lumbar lordosis. Obliteration of the lordosis will cause the individual to sit more posteriorly on the ischii and sacrum and may, actually increase seating problems.

Ambulatory individuals man, find it difficult to be mobile if they are constantly working to maintain their balance when upright. The complex relationship between the pelvis and the spine should he taken into account when considering spinal fusion. Some individuals are able to stand and walk independently by virtue of a mobile hyperlordotic lumbar spine, which may be compensatory for existing hip flexion contractures. Mobility of the trunk and trunk musculature may be used to assist lower-extremity movement in gait, such as with the RGO. Fusion resulting in the loss of lumbar lordosis will accentuate existing hip flexion contractures and make upright stance more difficult. In turn, increased weight bearing on the upper extremities may be required. A retrospective study by Mazur et al,(81) indicated that nearly one third of ambulatory individuals who underwent spinal fusion lost a functional level of ambulatory ability.

The Adolescent

The energy cost of ambulation is high in adolescents with thoracic and high-to mid-lumbar neurosegmental levels.(82) Body weight, which usually increases at this time, contributes to the difficulties.(83), Ambutation becomes less efficient in adolescence, and it becomes more difficult for the adolescent to keep up with peers. The adolescent, therefore, may choose the wheelchair for full-time functional mobility. Ambulation is usually done for therapeutic reasons only, with standing used for the purpose of transfers.

Adolescents with lower neurosegmental levels of involvement may request a wheelchair for community mobility and for participation in sports. We believe participation in sports should be encouraged, not only for the beneficial effects on coordination and trunk and upper-extremity strength, but also for the benefit of self-esteem. Many adolescents enjoy athletic activities such as basketball, tennis, weight lifting, swimming, and wheelchair racing.

Because wheelchair use may increase in adolescence, daily skin inspection and frequent push-ups to unweight the buttocks are imperative. Special wheelchair cushions are used to promote equal weight distribution and provide a firm base of support for the pelvis; however, they do not take the place of pressure-relief maneuvers. Skin ulceration has a major effect on the adolescent's function, because treatment may require surgical intervention, lengthy hospitalizations with restricted positioning, and major financial and personal costs, such as decreased peer and family interaction. - Preparation for transition to adulthood takes place during late adolescence. The adult with myelodysplasia faces problems with separation from family, locating independent living arrangements, developing vocational skills, and finding appropriate medical

The more prepared the adolescent, the easier the transition. The therapist may help by visiting the proposed living and vocational environments and making suggestions for accessibility. if medical care is to be assumed under adult services, communication by the treatment team who has monitored the individual will ensure an easier transition.

Summary

The physical therapist and orthopedist have a significant role in the assessment and treatment of the child with myelodyspl:lsia. Care of the individual with myelodvsplasia is a complex process and continues throughout life. Because the neurologic deficit may change over time in some individuals, treatment programs must be individualized and flexible. The nature and timing of various interventions may vary. The needs and status of the individual, the level of function, and stage of life should be considered.

Acknowledgments

We thank Alice Shea, ScD, PT, R Michael Scott, MD, Director of the Section of Pediatric Neurosurgery, and James Koepfler, medical photographer, all of Children's Hospital, Boston, Mass, for their assistance in preparing the manuscript.

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