Orthotic Management of the Child with a Meningomyelocele

J. RICHARD BOWEN, M.D.


Patients with meningomyelocele frequently require individualized orthoses to achieve maximum potential. A successful orthotic management program must include the orthotist, the orthopaedist, the pediatrician, the urologist, the neurosurgeon, and the physical therapist. This report presents a discussion of the general orthotic program used for 222 patients less than 13 years of age who are currently being treated in the Pediatric Meningomyelocele Clinic at the Alfred I. duPont Institute.

At birth virtually all meningomyelocele patients have a neurologic loss or muscle imbalance. In the flail extremity, postural deformities frequently occur; in an extremity with muscle imbalance, deformities are inevitable. Prophylactic splinting of the patient's foot has been most successful in preventing postural deformities. If the foot is in an acceptable plantigrade position, an ankle-foot orthosis is applied with the foot in a neutral position. For the infant the orthosis is made of orthoplast, which allows frequent adjustments for growth. For the older patients, polypropylene is utilized (Figure 1 ). Mild deformities are treated with physical therapy until the foot can be held in a neutral position, and an ankle-foot orthosis is used to maintain the acceptable position. In severe deformities, the foot is operatively corrected to a plantigrade position and then maintained by the ankle-foot orthosis. The orthosis is used at least 12 hours per day, and with some patients it is removed only during physical therapy sessions or bathing. Use of the orthosis should be continued at least until the patient is mature. Prophylactic splints have been used to maintain the knees and hips in functional positions but are far less successful.

When the patient with a lower-level meningomyelocele develops good head control and acceptable trunk control, sitting should be encouraged. A simple beanbag has been a very effective support and can be inexpensively purchased. For the child who needs more trunk control, a posterior molded-seat orthosis has been successful (Figure 2 ). To manufacture this seat, the child is placed on a cast table in a supine position with the hips flexed 90 deg. A plaster cast is applied from the axillary line to the knees, and then a mold is made from this casting. The seat orthosis is made over the mold, utilizing plastizote for the inner layer and orthoplast for the outer layer for the younger child, or polypropylene as the outer layer for the older child. Velcro straps are then connected to the seat at the chest and pelvic areas.

As the child matures, various orthoses are used to encourage standing. The standing frame (Figure 3 ), or parapodium, has been most successful for patients with high-level neurologic lesions. This frame is easy for parents to apply and is relatively inexpensive. The child is maintained in a good upright position with his hands free. Children with lower neurologic lesions are placed in bilateral conventional long-leg braces with pelvic bands and thoracic supports. There are drop-locks at the knees and hips; ankle motion is limited to approximately 15 deg. The patient is then held in a standing table, which consists of a plywood top with a circular cutout in which the patient stands (Figure 3 ). This arrangement allows a patient to lean against the table top and have his hands free for manipulative activities. Children rapidly learn to turn themselves in this device and learn to balance on their feet without fear of falling. Use of the bilateral long-leg braces in the standing table has several disadvantages: the braces are more difficult than the parapodium for parents to apply and are more expensive than the standing frames. As soon as the child is standing and moving about in the standing table, walking is encouraged.

In the initial therapy sessions the patient walks with the same braces used in the standing frame, and then progresses to ambulation in the parallel bars. As walking improves, the hips are unlocked. Subsequently, the pelvic band may be removed from patients who have good control of the lower extremities. This conventional orthosis will generally last about one year to 14 months. At night, when the patient is not utilizing the conventional brace, the ankle-foot orthoses are used as prophylactic splints. When a patient has passed the rapid growth phase, at approximately 4 years of age, polypropylene knee-ankle-foot orthoses are fitted (Figure 4 ). The orthoses have drop-lock knees, and the ankles are held at 15 deg. of dorsiflexion. Polypropylene orthoses are significantly lighter than conventional orthoses while offering good support for knees and ankles. For a young patient with a low neurologic level, long-leg braces are recommended to support the knees. Even patients with sacral neurologic levels frequently walk with the feet externally rotated, and this results in a significant rotation and valgus force to the knees. Hopefully, the extra support to the knees will diminish the incidence of ligamentous instability occasionally seen in the older patients.

When the patient reaches his preteen years, has excellent rotatory control of the legs, and has a low neurologic lesion, solid-ankle-type or floor-reaction-type ankle-foot orthoses are prescribed (Figure 5 ). The floor-reaction-type ankle-foot orthoses are prepared with the ankle in 15 deg. of plantar flexion, a solid ankle, and a pretibial shield. This orthosis is effective for patients with weak knee extensors and good sensation along the anterior pretibial skin. The floor-reaction ankle-foot orthosis works poorly for patients with flexion contractures of the knee or decreased sensation on the pretibial area. The solid ankle-foot orthosis is preferred more frequently by the patient than the floor-reaction ankle-foot orthosis. The solid ankle-foot orthoses are fabricated in a neutral-to-15-deg. dorsiflexion position to decrease the rotational stress at the knee.

Patients with marked spasticity of the lower extremities are more easily managed in conventional orthoses. Frequently these patients have had multiple shunt revisions, and the spasticity increases with decreased functioning of the shunt. The conventional orthoses allow frequent revisions and adjustments, whereas the polypropylene orthoses do not.

Patients with severe or rigid deformities of the feet are more easily fitted with conventional orthotic devices. Specially designed shoes provide more support and pad abnormal weight-bearing surfaces to help prevent callus formation or skin irritation.

We have established the following minimal bracing requirements for the lower extremities. High-level and thoracic neurologic lesions require bracing to the trunk level. Midlumbar-level neurologic lesions require long-leg braces. Myelomeningocele patients with low-level lesions require only below-knee orthoses or no external support.

Approximately half of our patients have significant scoliosis which requires spinal support. The orthoplast jacket orthosis (Figure 6 ), as described by Dr. G. Dean MacEwen, was first used with meningomyelocele patients in 1969 and has been extremely helpful in paralytic-type curves. The orthoplast jacket orthosis supports the spine, but will not correct or prevent scoliosis. Frequently progression of the scoliosis can be significantly retarded, but patients who progress should have a posterior spinal fusion before the deformity becomes severe.

For fabrication of the orthoplast jacket orthosis, the patient is placed on a fracture table and a Cotrel-type localizer cast is applied. X-rays are obtained with the patient in the localizer cast to determine acceptable correction. The cast is removed and used as a mold. The negative mold is filled with plaster of Paris, and the positive mold is then relieved as necessary to meet the patient's individual requirements. The orthoplast is molded on the plaster-of-Paris positive. The top and bottom of the orthoplast jacket are covered with moleskin, and straps are applied before patient fitting. The orthoplast jacket is not lined unless a patient has extremely fragile skin. The orthoplast jacket is applied with the patient wearing a soft cotton T-shirt, and X-rays are taken to be sure acceptable alignment is obtained. The orthosis is simple to make; it lasts approximately one year and can be used in combination with other orthoses.

Kyphosis is an extremely difficult problem to treat in patients with meningomyelocele. Currently, no orthosis adequately supports a congenital kyphosis, but multiple orthotic adaptations can be made to aid in function. When the patient is able to stand, a standing frame is fabricated with the area of kyphosis relieved. When the patient reaches walking age, he is given a bilateral long-leg brace with limited ankle motion, knee and hip locks, and thoracic support. Special attention is directed toward relieving the kyphotic area to prevent skin ulceration. This orthosis allows the patient to stand and sit. No patients with severe kyphosis have been good walkers. Almost all patients with severe congenital kyphosis have required wheelchair modifications (Figure 7 ). A box-shaped back is applied to the wheelchair, and the front of the box is relieved in a longitudinal fashion so that no area of the kyphosis contacts the back of the chair. The margins of the anterior aspect of the box are padded with foam and covered with typical upholstery material. The patient sits in the chair and leans back against the margins of the box for support. This wheelchair modification will frequently prevent skin ulcerations over the apex of the kyphosis.

Many meningomyelocele patients are on an intermittent catheterization program, and a special seating device is extremely helpful for female patients who have poor trunk control (Figure 8 ). This seat is inclined backwards and is slightly elevated. A mirror is positioned in front of the seat so the patient can transfer from a wheelchair to the seat and then adjust the mirror for the intermittent catheterization.