The acetabulum in congenital and neuromuscular hip instability.

Acetabular morphology in congenital and neuromuscular hip instability was evaluated with computed tomography (CT) and plain radiography. Thirty-three unstable hips in 27 children with congenital hip dysplasia, cerebral palsy, or spina bifida were studied. Fourteen normal hips in 14 children served as controls. Unstable hips in the children with congenital hip dysplasia demonstrated anterior and superior acetabular deficiency with increased acetabular anteversion. Global deficiency was present in acetabuli of cerebral palsy and spina bifida patients with anterior, posterior, and superior deficiencies. The acetabuli in cerebral palsy patients had significant posterior deficiency and were the shallowest of the groups evaluated.