Hip instability in myelomeningocele. 158 patients followed for 15 years.

In 158 patients with myelomeningocele, the prevalence of hip dislocation at birth and subluxation or dislocation of unoperated on hips at 2 and 15 years of age were assessed. In neonates examined during the first 10 weeks of life, 10 percent of the hips were dislocated. In children with a thoracic or L1-2 neurologic level, the cumulative incidence of dislocated hips increased from 8 to 26 percent and subluxations from 33 to 45 percent. In children with L3 and L4 levels, one fourth of the hips had dislocations and nearly half subluxations. At L5 and the sacral motor level, dislocations did not occur, but one fifth of the hips had subluxations. Children with L3 or L4 neurologic levels had bilateral hip dislocation at an earlier age than those with higher levels of paralysis. There appears to be no risk of developing hip dislocation at neurologic levels below L4, and spasticity promotes hip dislocation above L3.