The Role of the Thoracic Suspension Orthosis in the Management of Myelomeningocele Spinal Deformities

JAMES C. DRENNAN, M.D.


The thoracic suspension orthosis has proven to be an effective alternate method of controlling myelomeningocele patients with spinal deformity. It has resulted in a significant improvement in the quality of life for some of these patients and has allowed for the delay in surgical management in the skeletally immature patient.

Introduction

The majority of myelomeningocele patients develop significant spinal deformity. This fact requires the orthopaedist to be knowledgeable about alternate means of controlling spinal deformity in the upright position1. Many of these patients will eventually require surgical stabilization. However, structural deformity frequently develops in the skeletally immature patient when both operative techniques and the incidence of complication argue for a delay in spinal fusion. There are also patients whose cardiopulmonary and urologic compromise precludes surgery but who nonetheless require long-term orthotic control. The thoracic suspension orthosis has been developed as an effective alternative for both of these groups.

Myelomeningocele spinal deformities may develop because of congenital vertebral anomalies, instability resulting from the absence of both the neural arch and the posterior ligamentous complex, or increasing neurological deficit due to a progression of hydromyelia. Both congenital and acquired scoliosis, lordosis, and kyphosis may result from these factors.

The Thoracic Suspension Orthosis

The orthosis is constructed of Vitrathene which is lined with Plastizote. A carefully contoured undercut immediately beneath the rib cage converts the lower anterior and lateral thoracic cage into a partial weight-bearing structure (Figure 1. and Figure 2. ). The patient is suspended above the wheelchair seat by orthotic spools which are seated on hooks extending from the uprights of a regular wheelchair (Figure 3. ). Suspension allows the weight of the lower half of the body to act as a corrective distracting force against the orthotically fixed upper trunk. Individual spinal deformities can be accommodated by utilizing either a circumferential anterior-opening orthosis or an overlapping anterior and posterior orthotic shell combination.

Indications

Several important prerequisites must be fulfilled before the patient is accepted as a suspension-orthosis candidate2. Both the patient and the family must be made familiar with the medical need for the orthosis and the need for their cooperation when the patient is upright. Adequate hip flexion to allow sitting, the absence of excessive obesity or marked involuntary movements, and the presence of a qualified nursing, orthotic, and physician team are additional prerequisites.

Twenty-two Newington myelomeningocele patients have utilized the thoracic suspension orthosis. The most common indication has been the arrest or partial correction of progressive scoliosis, lordosis, or kyphosis, and associated comprised pulmonary function. The increased sitting balance and release of the upper extremities from their role of "trunk crutches" have allowed some patients to develop bimanual activities, including independent wheelchair propulsion. The relief of pressure on anesthetic trunk or buttock skin has led to improved control of recurrent decubiti.

Hospital Program

Hospitalization is required for all patients utilizing the thoracic suspension orthosis. Skin tolerance is carefully developed so that the shear and compression forces of the skin are kept below the maximum level of skin tolerance. The objective is to achieve two and a half hours of consecutive suspension before discharge. This period of time allows the patient and family to realize the functional advantages of the system and also assures that no significant orthotic problems persist. Initial admission is usually two to three weeks for implementation of this program. The average user requires refitting in 15 months with a two-to-three-day repeat hospitalization. Frequent orthotic modifications and additions may be required during hospitalization.

Disadvantages

The attachment to the wheelchair fixes the patient in one position in space. Myelomeningocele patients with adequate upper-extremity strength may be able to become independent in getting in and out of suspension, but may still note a lack of total mobility in a wheelchair. Problems of heat intolerance in warm weather are managed by frequent skin inspection and sometimes periods of recumbency out of suspension. One patient developed a full-thickness skin ulceration from an allergic reaction to adhesive tape placed about an ileal stoma bag. This ulcer eventually required plastic surgical closure.

References:

 

    1. Drennan, J. C., Orthotic management of the myelomeningocele spine. Dev Med Child Neurol, 18:97-103, 1976.

 

  1. Drennan, J. C., I. S. Renshaw, and B. H. Curtis, The thoracic suspension orthosis. Clin Orthop, 139:33-39, 1979.