Paralytic instability of the hip in myelomengoceles.

The results of a Colonna type arthroplasty with several modifications were evaluated in 29 hips of 22 myelomeningocele children with subluxations or dislocations. The operations were performed only in children with high neurosegmental levels where no muscle transfers were possible or when previous surgical procedures failed to maintain hip stability. Improvement in radiographic and clinical stability was demonstrated in 79 per cent of the hips. Eighty-three per cent of the hips lost motion in the flexion-extension arch with a mean loss of 30 degrees. The arthroplasty improved hip stability but at the expense of some loss of flexion-extension. Favorable results are more likely when the neurosegmental level is T-12 or above, the hip has had no previous operative procedure and the arthroplasty is accomplished without capsular interposition. Improvement of ambulatory status was impossible to evaluate because in any one case, the level of ambulation was determined by influences and physical factors other than the operation.