Peripheral Nerve Roots

Peripheral nerve development is not affected in myelomeningocele. At surgery and on dissection of postmortem specimens, normal peripheral roots are found in every case. However, inside the dura mater, the roots appear to have tenuous connections with the cord itself and are occasionally hard to identify.

Vertebrae

The principal defect is the arrested development of the posterior elements (laminae and spinous process). The posterior elements may be completely absent, in which case the pedicles alone are present, or there may be partial lamina formation. In the latter case, the intraspinal canal is widened as a result of lateral displacement of the pedicles on the vertebral bodies.

Thoracic Level

Patients with thoracic level lesions essentially have flail lower extremities and, based solely on the limbs’ total flaccid paralysis, would not be expected to develop muscle imbalance–induced lower extremity deformities. In fact, however, a frog-leg deformity is frequently present in these patients at birth, characterized by hip flexion, abduction, and external rotation contractures. In addition, there may be knee flexion and ankle equinus contractures. These may respond to judicious passive manipulation, but the hip contractures often do not respond adequately to this treatment, and the surgeon is faced with the decision whether to release the contractures to allow the lower limbs to be placed in a position for upright mobility. Occasionally, these patients develop secondary flexion deformities from spasticity in their lower extremities, which is actually presumed to be involuntary reflex motor function below the level of the myelodysplastic cord lesion. The most frequent deformities encountered by the orthopaedic surgeon in this patient group are spinal—congenital scoliosis, developmental scoliosis, and progressive congenital kyphosis.

Many patients with thoracic level lesions can achieve exercise or household ambulation as young children. All require extensive bracing above the hip and upper extremity aids (walker or crutches), and they ambulate with a swing-through gait using their upper extremities and abdominal muscles. The family must be aware that for most of these patients, this is a temporary capability. Because of the energy expenditure required for such ambulation, most patients ultimately choose to use a wheelchair full time, except for transfers. ^‡a

‡a References .

Upper Lumbar Level

Patients with upper lumbar lesions have hip flexor power and some adductor power, but no motor control of the knees or feet. For the most part, their ambulation potential and needs parallel those of patients with thoracic level function; theoretically, however, they may be more efficient walkers as children because their hip flexor and adductor strength can be recruited to provide a better swing-through gait or, with the use of a reciprocating gait orthosis (RGO), a reciprocating gait (see later, “Orthotic Management”). This iliopsoas strength is usually not sufficient in adolescence and adulthood, when the natural history resembles that of patients with thoracic lesions, in that they rarely continue to ambulate as adults. ^§a

§a References .

Lower Lumbar Level

Patients with lower lumbar lesions have greater hip adductor strength and, more importantly, quadriceps power to provide active knee extension. Those with L5 functioning have a functioning tibialis anterior, and they may have medial hamstring function as well. Hip strength is usually adequate to allow these patients to walk with the hips unbraced—that is, with knee-ankle-foot orthoses (KAFOs). Their gait exhibits a compensatory combined maximus-medius lurch (the limb in external rotation, and a backward and lateral lean of the trunk over the hip to stabilize it in stance). Some patients may be able to walk with only ankle-foot orthoses (AFOs); however, weakness of the foot, ankle, and hip abductors and extensors leads to a lurching gait that imposes a great deal of stress on the unbraced knee. These patients are also at high risk for the development of progressive hip subluxation and dislocation. Surgical treatment of the hip is most controversial in this group of patients in terms of its influence on the preservation of long-term ambulation. ^‖a

‖a References .

Sacral Level

Patients with sacral level myelomeningocele have near-normal knee function and more stable hip, foot, and ankle function. Their partial paralysis and insensate skin can lead to a number of foot problems, however, including cavovarus deformity, claw toes, and neurogenic ulcers. ^¶a

¶a References .

Long-term reviews of patients with sacral level paralysis are a sobering reminder of the multifactorial risk of losing neurologic function and mobility. Brinker and colleagues found that the ability to walk had declined in 11 of the 35 community ambulators (average age, 29 years), and a household ambulator had become nonambulatory; 15 patients had developed osteomyelitis, and 11 required amputations. In Selber and Dias’ report, 41 of 46 slightly younger patients (average age, 23 years) were still community ambulators, but 39 had undergone a total of 217 orthopaedic procedures and 12 had tethered cord release.

Closure of the Myelomeningocele Sac

Early closure of the sac (within 48 hours) is a cornerstone in the management of children with myelomeningocele. Before this became the standard protocol, death was almost universal secondary to meningitis and ventriculitis. Depending on the extent of the dermal defect and underlying bony deformity (specifically, congenital kyphosis), closure can be achieved by direct approximation of the skin over the defect, with or without undermining of the skin, local rotational flaps, or musculocutaneous latissimus dorsi or gluteus maximus flaps. Defects larger than approximately 18 cm are much more likely to dehisce after primary direct closure, and consultation with a plastic surgeon is generally indicated for the purpose of covering the skin defect with a flap. If required because of the underlying bony deformity, kyphectomy can be safely performed at the time of dural sac closure in neonates, with excellent initial correction. Eventual recurrence of the kyphotic deformity over time should be expected, however, despite the procedure. Fetal closure is discussed in the next section.

Hydrocephalus

The Chiari II malformation, characterized by herniation of the cerebellum and brainstem, is almost universally associated with myelomeningocele. This deformity, especially after closure of the myelomeningocele sac, produces an obstructive hydrocephalus, necessitating ventriculoperitoneal shunting in approximately 70% to 90% of infants. These shunts must be reevaluated periodically by the neurosurgeon to ensure continued function and absence of infection. Despite the presence of a shunt, the developmental delays, learning difficulties, and problems with executive functions are frequently seen in patients with myelomeningocele.

Although many patients have enlarged ventricles at birth, symptomatic hydrocephalus usually develops only after closure of the myelomeningocele sac. Thus many infants undergo closure of the sac within 48 hours of birth, develop hydrocephalus, and then undergo ventriculoperitoneal shunt placement. A study comparing staged and simultaneous sac closure and shunting found that patients treated by the simultaneous technique had a significantly reduced incidence of wound leakage at the closure site and no deleterious effects with respect to shunt failure, hydrocephalus, or CSF infection.

There is increasing evidence that the neurologic deficits in myelomeningocele patients are caused by the primary myelodysplasia compounded by exposure of the neural elements to amniotic fluid in utero. As noted, this led to the development of fetal surgical techniques to close the sac in utero in the hope of limiting the secondary neurologic injury. Preliminary reports in the small group of patients treated in this way have suggested that the need for ventriculoperitoneal shunting is reduced, from 90% to 60%. However, fetal surgery is associated with maternal and pregnancy complications, premature birth chief among them. Brainstem compression, presumably by the Chiari II malformation, can lead to respiratory obstruction and apnea. Sleep disturbances related to air hunger, dyspnea, and squeaky voice may all require assessment by a neurosurgeon for the possible presence of brainstem compression as the cause of these complaints.

Other Spinal Cord Abnormalities

Patients with myelomeningocele are subject to a number of other spinal cord lesions that may require assessment or treatment by a neurosurgeon, including hydromyelia, diastematomyelia, and tethered cord syndrome. ^‡b

‡b References .

Tethering of the spinal cord in scar tissue at the site of repair of the initial myelodysplastic lesion may be the source of significant symptoms as the child grows. ^§b

§b References .

MRI appearance of tethered cord in a patient with myelomeningocele. Normally, the conus should end at L1.

Sarwark and associates found that back pain resolved after surgical untethering, and curves stabilized or improved in 60% of patients with scoliosis and in 78% of patients with lower extremity weakness. Spasticity was least affected by surgical untethering, improving in only 43% of patients but stabilizing in the remainder. Pierz and colleagues reported that patients with curves less than 40 degrees experienced some improvement after an untethering procedure, but those with curves more than 40 degrees or thoracic neurologic levels had no improvement in scoliosis. McLaughlin and co-workers found that intraspinal rhizotomy and distal cordectomy were effective in ameliorating symptoms and lower extremity deformities caused by spasticity in patients with thoracic lesions. However, this treatment is indicated only for patients with no voluntary lower extremity function and in whom symptoms of spasticity cannot be controlled with lower extremity bracing or surgery.

Goals of Orthopaedic Management

Orthopaedists participating in the care of children with myelomeningocele are members of the health care team seeking to maximize function and minimize disability and illness. Over time, the specific goals change, based on the child’s needs and abilities and changes in neurologic status. One of the major goals of the orthopaedist is to correct deformities to help patients meet their maximal functional capability. Almost all patients need orthoses to replace muscle strength and joint stability so that they can stand and walk. Regardless of the extent of the deformity and paralysis, it is possible for most children to walk at a young age with a combination of deformity correction, bracing, upper extremity aids, and instruction. Thus one of the primary functions of the orthopaedist is to correct lower extremity deformities that prevent the patient from using orthoses to ambulate during childhood. Many patients, especially those with thoracic or upper lumbar paralysis, will be unable or unwilling to maintain the same level of independent ambulation as adolescents or adults because the extent of bracing and energy consumption required for ambulation will be too great. Patients with myelomeningocele should be prepared for independent, self-sufficient living, which means that they should not be devoting a substantial portion of their energy solely to walking for its own sake. Excessive emphasis on ambulation over the use of a wheelchair may even adversely affect academic achievement.

The orthopaedic surgeon must monitor spinal balance and deformity in the myelomeningocele patient. There is a high incidence of congenital and neurologically related scoliosis and kyphosis, conditions that can jeopardize posture or sitting comfort or increase the likelihood of the development of pressure sores.

Finally, the orthopaedic surgeon must assist in monitoring the neurologic status of the growing patient because hydrocephalus, hydromyelia, or tethered cord syndrome secondary to diastematomyelia or another anomaly or to scarring at the original level of myelodysplasia can occur. Any of these conditions can result in a subtle deterioration in the patient’s intellectual function and upper or lower extremity function.

In an effort to help orthopaedic surgeons understand what is required to achieve treatment goals for this complex disorder, experts from around the world convened in a symposium in 2000. The discussions from that meeting were published in a comprehensive report from the American Academy of Orthopaedic Surgeons describing the many facets of the orthopaedic care of children with spina bifida.

Physical and Radiographic Examination of the Newborn

When examining a newborn with myelomeningocele for the first time, the goal of the orthopaedic surgeon is to identify the level of paralysis for each extremity and screen for associated deformities. Sphincter control, the presence of hydrocephalus, and the condition of the myelomeningocele sac are also important to note. Commonly, the orthopaedist is consulted after closure of the sac and shunting for hydrocephalus. The infant should be examined in a quiet warm environment to allow the best assessment of joint range of motion, sensory preservation, and evidence of spinal deformity. A stimulated or crying infant, however, allows the examiner to appreciate the child’s voluntary lower extremity muscular function better. Sharrard described the neurosegmental function of the lower extremity, and this root by root assessment has become the standard for describing lower extremity function and the basis for establishing a prognosis for long-term ambulation and the nature of secondary deformities likely to develop during childhood. The level of spinal cord lesion as visualized on prenatal ultrasonography has been positively correlated with the level of postnatal paralysis noted on physical examination, so if this information is available, it may be helpful. Caution is advised, however, because determining the precise level of function can be difficult, and the level may change over time, may be asymmetric, or may not correspond exactly to Sharrard’s neurosegmental scheme. In a longitudinal serial evaluation of 308 patients older than 5 years, McDonald and colleagues found that quadriceps strength correlated with iliopsoas strength, medial hamstring function could be present without tibialis anterior function, gluteus medius and maximus strength correlated strongly with each other and with tibialis anterior strength, and muscle weakness was most frequently noted in the gastrocnemius-soleus group.

During the examination, the orthopaedist should first develop a sense of the child’s overall vigor because lack of vigor may suggest CNS depression caused by untreated hydrocephalus. Whenever expedient, the examiner should turn the infant prone on the mother’s lap, an examining surface, or the palm of the examiner’s hand to determine at what level the myelodysplastic deformity is located, its extent, and the state of the skin overlying it, especially if the examination is being conducted after neurosurgical closure of the myelodysplastic lesion. The infant should also be assessed for obvious spinal deformities or congenital scoliosis or kyphosis associated with the myelodysplastic lesion. The examiner then looks for more subtle evidence of spinal dysraphism at other levels—specifically, for discoloration or hemangiomas, hairy patches, or dimpling along the spinal column remote from the obvious myelodysplastic lesion. The entire spinal column is palpated, with the examiner looking for curvature or defect.

With the child supine, neck mobility and upper extremity formation and function are assessed; these are generally normal in the myelomeningocele patient. Next, the examiner visually inspects the posture of the lower extremities, which provides a clue to the extent of the paralysis. For example, a child with a thoracic level lesion most often lies supine with the legs in a flopped open, frog-leg position, with no spontaneous movement. Patients with lower levels of paralysis exhibit spontaneous movement of the lower extremities; if necessary, the examiner can stimulate the child to observe such movement. Specifically, the examiner should look for hip flexion and adduction, knee extension and flexion, and ankle dorsiflexion and plantar flexion. A note of caution is in order, however, because observed toe movements should not be taken as indicative of volitional control of the digits, and movement of the toes usually results from root sparing below the myelodysplastic lesion and is not under volitional control. The examiner should try to assess the level of preservation of sensation by gently stroking the skin, beginning distally, and observing the infant’s facial and lower extremity muscular response. The examiner checks for the usually obvious foot deformities, such as clubfoot and vertical talus. Range of motion of the hips is assessed, with specific noting of abduction, adduction, external rotation, and/or flexion contractures. The hips are also assessed for concentricity and stability. Knee flexion contractures and their extent should be documented. The examiner strokes the patient’s legs on both sides individually, from distal to proximal, by dermatome, to identify the level of sensory preservation. Finally, the examiner checks for the almost invariably present patulous anus and urinary dribbling, suggesting bowel and bladder paralysis.

The physical examination should be supplemented with good anteroposterior and lateral radiographs of the entire spine. These radiographs should be carefully inspected for the level of the last closed posterior element, any congenital spinal deformity (particularly one remote from the myelodysplastic level), and pedicular widening, especially with associated congenital vertebral anomalies, which may suggest underlying diastematomyelia. In general, the level of paralysis noted on physical examination should correspond to the first open level of the spine; however, there may be a substantial discrepancy between these two findings, which suggests that other deformities of the spinal cord or proximal CNS are contributing to the paralysis. Ultrasonography or MRI of the spinal cord may be indicated in these cases. In general, radiographs of the lower extremities merely confirm what has been determined from the physical examination. Ultrasonography can clarify the relationship of the femoral head and acetabulum if the clinical examination of the hip is not definitive.

This examination provides the orthopaedic surgeon with a good understanding of the lower extremity anomalies, extent of lower extremity paralysis, and presence of vertebral anomalies that need to be monitored with growth. The sum of these findings allows the surgeon to provide the patient’s parents with a reasonable outline of what will be required to correct the deformities and what they should expect in the future in terms of bracing needs and mobility expectations.

Periodic Assessment

Patients with myelomeningocele require periodic reassessment throughout growth, usually on a semiannual or annual basis. These assessments are typically carried out in a multidisciplinary clinic; this reduces the number of physician visits for the patient and family and allows the health care team to provide a comprehensive evaluation and coordinated treatment plan when interventions are required. Within this complex screening and treatment program, at each routine visit, the orthopaedist assesses whether the following are present:

• 1.
  

  The child’s motor and sensory function have remained stable.

  
  
• 2.
  

  The child’s mobility and bracing needs have remained stable.

  
  
• 3.
  

  Orthoses and upper extremity aids are appropriate to the patient’s requirements, provide the desired effect of maximizing mobility, are in good repair, and are not causing any undue pressure points on the patient’s lower extremities.

  
  
• 4.
  

  The range of motion of the patient’s lower extremity joints is stable and sufficient to allow the patient maximum mobility based on preserved motor strength.

  
  
• 5.
  

  The patient’s upper extremity function is stable.

  
  
• 6.
  

  Spinal deformity is stable or absent.

  
  
• 7.
  

  The patient’s skin is in good condition over the spinal deformity, in the perineal and ischial areas, at pressure points under orthoses, and over the knees and around the feet, where abuse of the skin may occur with crawling, walking, or swimming without braces or other protection.

These evaluations may be accomplished with the aid of a nurse, pediatrician, therapist, and orthotist. Periodic radiographic assessment of the spine and hips is often required as well; it is rare that a patient has no evidence of spinal or hip deformity on physical examination.

Foot and Ankle Deformities

Congenital and developmental foot deformities are common in children with myelomeningocele. Calcaneal deformity is the most common, followed by equinus, valgus deformity, clubfoot, and vertical talus. Foot deformities often interfere with effective bracing for ambulation or lead to pressure sores in ambulatory patients. Broughton and colleagues found that acquired deformities could not be accounted for solely by spasticity or muscle imbalance. Even nonambulatory patients have concerns about the cosmetic appearance of the feet and experience difficulty wearing normal shoes.

In general, foot deformities in an infant should undergo a trial of gentle passive manipulation, with care taken to avoid pressure sores and fractures. Even with early correction, recurrence is common, and surgery is ultimately needed on most feet. When required, it is important that surgical correction be delayed until the child is developmentally ready to be in the upright position. Proceeding with surgery for foot deformity before the patient is ready to be fitted with orthoses for standing or walking risks recurrence before the child even begins to walk. Early recurrence of the deformity can be minimized by ensuring that after the removal of postoperative casts, well-fitting orthoses are immediately available for use day and night, and the child should be encouraged to stand or walk in them.

Equinus

Pure equinus contractures in patients with myelomeningocele are common. They are not caused by voluntary muscle imbalance, however, because most patients have flail feet or, in patients with low lumbar lesions, tibialis anterior functioning. Positioning deformity, in utero or postnatally, and gastrocsoleus spasticity account for some of the equinus contractures seen and, in some patients, equinus develops after tibialis anterior tendon transfer to the calcaneus (see later, “Calcaneal Deformity”).

Patients with positional neonatal equinus contractures associated with higher level paralysis can initially be treated with extremely gentle passive manipulation. If the equinus deformity persists when the child is ready for orthoses for standing and ambulation, percutaneous release or open lengthening of the heel cord can be carried out. Percutaneous heel cord lengthening can be performed in the outpatient clinic if the patient is insensate in that area. Some patients have long toe flexor contractures as well, which should be divided. Otherwise, persistent toe flexion deformities can result in pressure sores on the ends of the toes when the child is placed in shoes. Careful postoperative casting for a few weeks should be followed by the fitting of orthoses required for standing or ambulation.

Equinovarus

Clubfoot deformity is a common anomaly in patients with myelomeningocele, irrespective of the level of myelodysplasia. ^#b

#b References .

References .

When nonoperative or minimally invasive techniques fail, extensive release is often required, and ancillary procedures such as lateral column shortening are required much more frequently than in patients with idiopathic clubfeet. In patients with lower lumbar lesions, the tibialis anterior tendon may be lengthened or transferred to the midline or heel (see later, “Calcaneal Deformity”). In patients with upper lumbar or higher lesions, tendons are frequently resected rather than lengthened. Only in patients with almost complete preservation of lower extremity function is typical tendon lengthening performed rather than resection. Furthermore, much as in patients with arthrogryposis, myelomeningocele-related clubfeet may require naviculectomy, talectomy, or talar enucleation (Verebelyi-Ogston procedure) to achieve correction. Infrequently, in the most severe deformities, bringing the foot into a corrected position may cause vascular compromise, requiring combining clubfoot correction and tibial and fibular shortening. Difficulty with wound closure is common, and rotational flaps have been described for primary closure of the surgical incision. I have found, however, that it is most effective to leave the wound open as much as necessary with the foot in the corrected position, provided that circulatory status is not impaired in that position, and to change the cast or window it for dressing changes. An alternative is to close the skin loosely and bring the foot into a corrected position with a few cast changes in the first 2 weeks after surgery. Inadequate skin coverage for surgical correction of recurrent clubfoot deformities has been addressed with the preoperative use of soft tissue expanders, but with only limited success (in two of seven cases).

Postoperative casting must be meticulous, as described earlier. Excessive swelling, erythema, or systemic reaction must be investigated by removing the cast and inspecting the foot. Wound necrosis and pressure sores are frequent, even with casting by the most experienced and attentive of surgeons, and families should be so warned. Bracing of at least the foot is required indefinitely after cast removal, so the surgeon should ensure that the required orthoses are ready to be applied when the cast is removed. The postoperative casting protocol may be shortened in favor of braces compared with that in patients with idiopathic clubfeet.

Recurrence of deformity can be treated by primarily bony procedures, including midfoot and forefoot osteotomies, talectomy, or triple arthrodeses When using these procedures, the surgeon must be careful to obtain even weight-bearing forces to minimize the predisposition to the development of neurotrophic ulcers. A variation of equinovarus deformity may be seen in patients with lower lumbar paralysis with a functioning anterior tibialis. In some of these patients, a deformity consisting of primarily forefoot dorsiflexion and supination gives the impression of a deformity caused solely by the unopposed action of the tibialis anterior or a very mild clubfoot. In infants with such a deformity, posterior or lateral transfer of the tibialis anterior alone may not correct all components of the deformity, and a limited posteromedial release is often required as well.

Calcaneal Deformity

Calcaneal deformity may be seen as a birth contracture or as a delayed deformity secondary to the unopposed action of the tibialis anterior in patients with paralysis at the lower lumbar level. ^†c

†c References .

Calcaneal foot deformity in a patient with a low lumbar level myelomeningocele. In addition to making bracing difficult, this deformity places the patient at risk for the development of neurotrophic ulceration of the heel and calcaneal osteomyelitis.

Patients with mild calcaneal deformities from birth, with the possible exception of those with tibialis anterior–sparing involvement, may respond to gentle passive stretching of the foot into plantar flexion and splinting in a neutral, weight-bearing position. Patients with persistent or progressive calcaneal deformities associated with unopposed tibialis anterior function frequently require anterior release of the deformity, usually combined with posterior transfer of the tibialis anterior to the calcaneus to facilitate brace fitting and prevent the development of calcaneal plantar ulcers. ^‡c

‡c References .

Vertical Talus

Congenital vertical talus occurs with greater frequency in patients with myelomeningocele than in the general population, although it is much less common than clubfoot and other deformities of the foot. The manipulative treatment discussed for the management of vertical talus in Chapter 23 may be used in patients with myelomeningocele. However, the treating surgeon must be cognizant of the increased likelihood of pressure sores and recurrence of deformity. Patients with vertical talus and spina bifida usually require surgical correction, which is the same as for any patient with congenital vertical talus (see Chapter 23 ). The principles of timing and postoperative management raised in the discussion of clubfoot in patients with myelomeningocele apply here as well. Specifically, surgery should be delayed until the patient is neurodevelopmentally ready for orthoses and ambulation. Postoperative casting must be meticulous and hold the foot in a neutral functional position, and bracing and weight bearing should be instituted as soon as the casts are removed.

Valgus Deformity of the Foot and Ankle

Valgus deformity at the ankle is a common deformity in ambulatory patients with myelomeningocele, irrespective of the level of paralysis. ^§c

§c References .

Valgus deformity at the ankle in myelomeningocele. This deformity may lead to ulceration over the medial malleolus or head of the navicular from rubbing against the ankle-foot component of the patient’s orthosis.

Distal Tibia.

Surgical options for the management of distal tibial valgus deformities include distal tibial and fibular osteotomy, distal tibial medial hemiepiphysiodesis or growth tethering with implants such as staples, screws, and plates, and Achilles tendon–distal fibular tenodesis. A distal tibial valgus deformity that causes pressure sores and cannot be corrected by adjustment of orthoses or such a deformity in a skeletally mature patient requires a distal tibial osteotomy and varus realignment ( Fig. 36-9 ). Skeletally immature patients with deformities that are progressive but not in need of immediate correction are candidates for medial tibial hemiepiphysiodesis or Achilles tendon–fibular tenodesis. The medial growth arrest may be affected by direct curettage, stapling of the medial side of the distal tibia, or insertion of a fully threaded screw percutaneously from the medial malleolus proximally across the physis. An Achilles tendon–fibular tenodesis is indicated for young patients with mild distal tibial valgus deformities who are considered too young for an epiphysiodesis of the distal tibia.

Distal tibial osteotomy for ankle valgus. A, Preoperative radiographic appearance. B, Postoperative radiographic appearance. Note displacement of the distal fragment laterally to prevent excessive prominence of the medial malleolus. The fibular osteotomy should be placed as distally as possible to prevent excessive prominence of the distal fragment on the lateral side of the ankle.

Distal Tibial Osteotomy.

Fixation may be done with crossed Steinmann pins, staples, external fixator, or internal fixation with a dynamic compression plate. This osteotomy may be complicated by delayed union, nonunion, or infection, particularly in adolescents. Recurrence of the deformity is also relatively common in skeletally immature patients. Postoperatively, patients should be kept non–weight bearing initially because weight bearing with diminished pain perception can lead to excessive swelling and motion. Patients should also be counseled not to crawl in postoperative casting. If possible, the knees should not be flexed excessively in long-leg casts because this can cause rehabilitation difficulties after cast removal.

Distal Tibial Medial Hemiepiphysiodesis.

If the patient is skeletally immature, with a deformity that does not demand full and immediate correction, a medial hemiepiphysiodesis can be considered. The medial tibial physis can be closed with direct surgical ablation, stapling, or insertion of a medial malleolar screw. The advantages of this technique are that immediate weight bearing is usually allowed and external immobilization is not necessary.

Achilles Tendon–Fibular Tenodesis.

Stevens and Toomey described the tenodesis of a portion of the Achilles tendon to the distal fibula above the distal fibular physis. Their rationale was that the valgus deformity is secondary to lateral compartment paralysis, with subsequent underdevelopment of the fibula, and that this lack of growth stimulation can be compensated for by tenodesis of a slip of the Achilles tendon to the fibula. With weight bearing and ankle dorsiflexion, the tenodesis pulls downward on the fibula, leading to gradual correction of the deformity. The surgical procedure is outlined in Plate 36-2 . Similar to distal tibial hemiepiphysiodesis, this procedure is indicated for skeletally immature patients with progressive deformities that do not yet require complete correction. It is particularly well suited for younger patients in whom hemiepiphysiodesis is not appropriate.

Rotational Deformities (Internal or External)

Rotational deformities of the lower extremities are frequent in ambulatory and nonambulatory patients. In nonambulatory patients and in most ambulatory patients, the problem is largely cosmetic. Extreme internal rotation may interfere with ambulation if the child is catching his or her foot on the contralateral extremity during swing. Internal rotational deformities are usually dynamic, secondary to medial hamstring dominance, or fixed, secondary to internal tibial torsion. When a dynamic internal rotational deformity is interfering with gait, Dias and associates reported good results with transfer of the semitendinosus to the biceps and head of the fibula, but I have no experience with this procedure. Internal tibial torsion can be treated by rotational osteotomy. I prefer to perform a tibial osteotomy distally with fixation with crossed Steinmann pins or a dynamic compression plate.

Marked external rotation, in addition to being cosmetically displeasing, may indirectly interfere with ambulation by making the fit or function of the AFO component of bracing more difficult. The external rotational deformity places the medial malleolus in the line of progression of the limb and may lead to constant skin breakdown from rubbing against the AFO. This problem is aggravated if there is valgus deformity of the ankle or hindfoot as well. In addition, the calcaneus-preventing action of the orthosis, particularly a ground reaction orthosis, may be rendered ineffective if the external rotational deformity moves the foot sufficiently out of the line of progression of the patient’s gait ( Fig. 36-10 ). An external rotational deformity may come from the hip but is usually found in the tibia. Treatment consists of internal rotational osteotomy of the affected segment (usually the tibia), which Vankoski and co-workers believe should be considered when external torsion exceeds 20 degrees.

Extreme external tibial rotation takes the foot out of line in terms of gait progression, making stabilization of the foot and ankle for weight bearing in an ankle-foot orthosis ineffective.

The surgeon must carefully assess the nature of the patient’s gait and extent to which the deformity should be corrected before recommending rotational osteotomy. Patients who ambulate with little knee motion—that is, who advance their limbs primarily by hip flexion or adduction with the hip externally rotated (typical of patients with upper lumbar level paralysis)—will have difficulty clearing a foot in swing that points directly in the line of progression. In these patients, the external rotational deformity should not be corrected if no gait or bracing problems are present. If rotational osteotomy is undertaken, the surgeon should aim to have the angle of foot progression in a more acceptable position of external rotation. Satisfactory results with distal tibial osteotomy have been reported in 80% to 90% of cases. However, significant complications have been reported and include delayed union (averaging 6 months to union), wound infection, and persistent swelling. Note that I do not recommend a rotational osteotomy of the tibia in a patient with myelomeningocele without a serious consideration of the potential sequelae weighed against the extent to which the rotational deformity is creating problems for the child.

Knee Deformities

The knee is not prone to many congenital anomalies in patients with myelomeningocele and is a surprisingly hardy joint in these young patients. However, long-term studies in ambulatory patients with low lumbar or sacral lesions suggest that knee instability, with or without pain, is present in about 25%.

Hip Deformities

No aspect of the orthopaedic management of patients with myelomeningocele is more controversial than the proper management of the hip joint. ^‖c

‖c References .

General Management of the Spine

Radiographic evaluation of the entire spinal column should be carried out in infants with myelomeningocele, looking specifically for the presence, location, and severity of kyphosis, the last level of posterior element closure, and any evidence of congenital spinal deformity ( Fig. 36-12 ). The last includes failures of formation or segmentation, as with any congenital spinal anomaly (see Chapter 12 ), and pedicular widening or secondary posterior element incompleteness, which may indicate the presence of diastematomyelia. Routine physical examination and periodic radiographic screening for evidence of scoliosis should be performed in all patients with spina bifida because the prevalence of this deformity is so high.

Congenital abnormalities of the spine associated with myelomeningocele. Spinal dysraphism and congenital vertebral anomalies are often best appreciated on infant films. In all infants with myelomeningocele, radiographs of the entire spine should be obtained and studied for evidence of these deformities. This radiograph demonstrates opening of the posterior spinal elements from the L1 level, a hemivertebra at T8, and a butterfly vertebra at T6.

Congenital spinal deformities are managed as in any other patient; if the deformity is progressive, local anterior and posterior spinal fusion is carried out (see Chapter 12 ). Progressive neuromuscular (noncongenital) curves are treated according to their severity, evidence of progression, and the patient’s skeletal maturity. First, the overall health of the patient’s neurologic system should be evaluated, particularly in those with newly evident or rapidly progressive deformities. Shunt function should be assessed and the spinal cord evaluated for evidence of tethering, hydromyelia, or diastematomyelia. Curves between 25 and 45 degrees in skeletally immature patients may be considered for total-contact orthoses. Bracing in ambulatory patients dependent on extensive lower extremity braces, particularly HKAFOs, can be challenging, but because spinal orthoses can at least delay the rate of progression of deformity, they should always be considered; bracing should probably be recommended for young patients in whom deferral of spinal fusion is warranted. As for patients with idiopathic scoliosis, spinal fusion should be considered for curves greater than 55 degrees unless the patient is a community ambulator. In this case, spinal fusion to the pelvis should be delayed until the patient becomes largely wheelchair-reliant or the curve becomes significantly worse.

Patients with myelomeningocele who undergo spinal surgery are particularly likely to experience peri- and postoperative complications, making attentive treatment by an expert health care team essential. Even with such care, pressure sores, urinary tract infections, wound breakdown, deep infections, pseudarthrosis, and progression of the deformity are more frequent than in all other patient populations with spinal deformities.

Preoperatively, the treating surgeon must ensure that the patient’s shunt function is stable, there is no ongoing urinary tract infection, the weight-bearing skin of the pelvis and upper thighs is free of pressure sores, and the skin over the portion of the spine to be operated on is healthy. Preoperative assessment should include careful assessment and neurosurgical consultation to assess the potential need for prior or concurrent detethering of the spinal cord.

Postoperatively, the wound must be carefully monitored and promptly attended to if there is evidence of superficial or deep infection or tissue necrosis. The patient’s urinary tract must be kept clean. The patient’s perineal skin must be carefully monitored when the patient resumes sitting—the load of weight bearing will have changed anatomically because of the deformity correction, and there is always some loss of lumbopelvic movement with fixation to the pelvis, which likely increases the pressure in load-bearing areas in a sitting patient. Wheelchair seating modifications should be made in the early postoperative period, prior to initial postoperative discharge, to lessen the likelihood of skin problems associated with the change in posture. Finally, if a patient performs independent transfers with flail or almost flail extremities, the surgeon must observe these transfers preoperatively to determine whether fixation to the pelvis will allow these movements postoperatively. I encourage one- or two-person assisted transfers for 6 to 8 weeks postoperatively to prevent excessive lumbopelvic movement through the limbs, which can occur with independent transfers. Rarely, a spine-thigh orthosis may be needed to protect the lumbopelvic junction from excessive movement during this period.

Kyphosis

Kyphosis of the lumbar spine is a common deformity in myelomeningocele patients (20% to 46%; Fig. 36-13 ). They have been described as paralytic, sharp-angled, and congenital. Carstens and co-workers found paralytic kyphosis (<90 degrees at birth) to be most common (44%), followed by sharp-angled kyphosis (≥90 degrees at birth; 38%). Both types of kyphotic curves progress during growth at a rate of 2 to 6 degrees/year. The progression of true congenital kyphosis was the least common (14%) in Carstens and colleagues’ series, and progression was variable during growth. Kyphosis is usually seen in patients with thoracic and upper lumbar levels of paralysis. Progressive kyphosis is usually associated with a compensatory thoracic lordosis ( Fig. 36-14 ). Mintz and co-workers noted that progressive kyphosis was associated with the loss of any previously preserved lower extremity function.

Clinical appearance of severe lumbar kyphosis in a patient with myelomeningocele. The patient sits on the upper thighs. The skin over the kyphotic area is easily traumatized.

Patients with lumbar kyphosis typically have a compensatory thoracic lordosis.

Management of Skin Breakdown.

The treatment of myelomeningocele-related kyphosis is always challenging. Lumbar kyphosis can be problematic from birth, causing difficulty closing the skin and the meningeal defect. Later difficulties include skin breakdown with sitting, sitting balance problems, and even pulmonary compromise caused by pressure on the thoracic cavity from the collapsing abdomen and diaphragm. Chronic skin breakdown can leave the neural elements and the spinal column exposed and at risk for infection ( Fig. 36-15 ).

The consequence of severe kyphotic deformity is often unstable skin that is prone to repeated breakdown over the deformity.

If the kyphosis prevents adequate skin closure at birth, one or two largely cartilaginous vertebral bodies can be enucleated and the remaining spine held together with sutures or cerclage wire ( Fig. 36-16 ). Excellent initial correction can be achieved, but eventual recurrence of the kyphosis should be expected. However, recurrence takes the form of a more rounded deformity, which may require a less technically demanding correction in the future.

Congenital kyphosis can be treated by partial vertebrectomy at birth if necessary to close the skin over the myelomeningocele defect. Typically, the deformity recurs with growth, and further procedures may be necessary.

Patients with skin breakdown over a stable kyphosis that does not need treatment should have their wheelchair supports and activities carefully evaluated and any irritants causing the breakdown removed. If these efforts are unsuccessful, rotational or free flaps can be used to cover the kyphotic area with thicker, more stable skin. Soft tissue expanders have been used for this purpose as well, independently and in conjunction with spinal deformity correction.

Kyphectomy

Technique.

Sharrard was the first to describe the technique of vertebrectomy in the management of kyphotic deformity in newborns and later in older children, as described by Sharrard and Drennan. At surgery, the neural elements are dissected away from the posterior spinal elements (see Plate 36-3 ). In patients with no function below the level of resection, the nerve roots and cauda equina remnants can be resected by tying the roots, elevating the distal cord, and transecting it. The meninges should be dissected free of the neural elements, resected distal to the elements, and sutured closed. The spinal cord should not be tied because acute hydrocephalus may result, possibly causing sudden death. After resection of the cord, the lumbar spine is dissected extraperiosteally from the posterior approach to the anterior aspect of the vertebral bodies. Two or more vertebral bodies are resected through their midportions so that the kyphosis can be reduced. Fixation to the pelvis is then carried out. A number of instrumentation techniques have been described, including fixation with Harrington compression instrumentation, Luque-Galveston instrumentation to the iliac crests, the Dunn-McCarthy modification of Luque instrumentation to the sacral alae, Luque rods contoured to fit through the first sacral foramen per the Fackler technique (a modification of the Dunn-McCarthy technique), vertebral body plates, and figure-eight wire loops around the pedicular remnants, with immobilization in a cast or brace ( Fig. 36-17 ). ^§d

Fixation options for definitive surgical management of kyphosis. A, Luque segmental wire and Galveston instrumentation fixation to the pelvis. B, Luque wire with Dunn-McCarthy fixation to the pelvis. This is my preferred stabilization technique.

§d References .

My preferred technique is to use Dunn-McCarthy rods over the sacral alae in older children, with posterior pedicular wire loops or vertebral body screws, and to use pedicle screws from the lowest level at which they are intact to the T2 or T3 level proximally. In young patients (6 to 10 years), I prefer the Fackler technique, in which a contour rod is placed anterior to the sacrum through the first sacral foramen. In younger patients, I have also used sublaminar wires without fusion in the upper thoracic spine to allow for growth. There have been recent reports of using the vertical expandable prosthetic titanium rib (VEPTR) to treat young patients with severe kyphotic deformity. The high rate of complications in patients undergoing one-stage, definitive spine surgery has resulted in bias against the use of so-called growing techniques, which require multiple planned operations in patients with myelomeningocele; I prefer to use nonoperative delaying tactics (i.e., casts and braces) in very young patients and perform single-stage definitive surgery after the age of 6 years.

Results.

Martin and co-workers reported improved skin condition and sitting posture in all 10 patients treated by vertebrectomy, figure-eight wire fixation, and postoperative cast immobilization at an average age of 5 years. However, lower extremity fractures, delayed wound healing, and pseudarthroses occurred. The average degree of deformity was 90 degrees preoperatively, 40 degrees postoperatively, and 60 degrees at an average follow-up of 5 years.

Warner and Fackler found that 8 of 21 patients in whom kyphosis was stabilized with Harrington compression instrumentation, but none of 12 patients treated by fixation anterior to the sacrum (modified Dunn-McCarthy technique) and instrumentation, had recurrence of kyphosis on follow-up. Improved deformity correction using the Dunn modification of segmental fixation also has been reported by others. McCall reported that preoperative deformity averaged 110 degrees, postoperative deformity averaged only 15 degrees, and loss of correction averaged only 5 degrees on follow-up. Of 16 patients, 8 had complications, and blood loss averaged 1100 mL.

Garg and colleagues achieved improved seating balance and skin conditions in 17 of 18 patients undergoing kyphectomy. Seven patients required reoperation and three developed deep infection. One patient who had removal of implants following deep infection developed recurrent deformity. As a result of this experience, anterior fusion prior to implant removal is now recommended for patients who develop deep infection.

Odent and associates reported nine patients who underwent a two-stage procedure consisting of a posterior kyphectomy using lumbar pedicle screws and long, S -shaped rods buttressing the anterior sacrum and a thoracoabdominal approach to the spine, with an inlay strut graft from T10 to S1 as a second operation several weeks later. Kyphosis was corrected from a mean of 110 degrees before surgery to 15 degrees afterward, with no instrumentation failure, loss of correction, or pseudarthrosis. The authors believe that this technique improves biomechanical and biologic fusion mass anteriorly and should prevent late instrumentation failure and loss of correction. Caution is advised, however. It is generally agreed that kyphectomy with instrumentation is a major surgical procedure, intraoperative blood loss is usually well in excess of 1000 mL, perioperative deaths have occurred, and postoperative complications, including skin breakdown, infection, loss of fixation, and recurrence of deformity, occur more frequently than after most other orthopaedic procedures. ^‖d

‖d References .

Scoliosis

Scoliosis in patients with myelomeningocele may be congenital, idiopathic-like, or related directly or indirectly to the spinal dysraphism and associated paralysis (associated intrathecal anomalies such as tethered cord, hydromyelia, or diastematomyelia; paralytic pelvic obliquity; asymmetric paralysis). Scoliosis is one of the most common musculo­skeletal deformities requiring treatment in patients with myelomeningocele (52% to 70%, most by 6 years of age), and 50% of them will require surgery. ^¶d

¶d References .

Noncongenital scoliosis in young myelomeningocele patients is highly likely to progress by an average of 5 degrees/year. The severity of the curve and age of the patient are risk factors for progression—curves of more than 40 degrees are much more likely to progress, and curves continue to develop until age 15 and progress only slightly thereafter. Curves less than 20 degrees often resolve. The clinical motor level, ambulatory status, and last intact laminar arch are all predictive factors for the development of scoliosis.

Hyperlordosis

A less common spinal deformity in patients with myelomeningocele is hyperlordosis, with or without associated scoliosis. Hyperlordosis can lead to difficulty sitting, intertriginous skin breakdown, and difficulty with self-catheterization in females because of the posterior rotation of the perineum ( Fig. 36-18 ). In the past, this deformity was associated with lumboperitoneal shunting, but this method of shunting is rarely used today. Treatment, when required, is by a combination of anterior and posterior spinal release and posterior instrumentation; in severe rigid deformities, postural reduction in traction after spinal release, before definitive instrumentation, may improve the deformity.

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