Location of acetabular deficiency and associated hip dislocation in neuromuscular hip dysplasia: three-dimensional computed tomographic analysis.

Forty-one hips in 24 patients with neuromuscular disease (NMD) were studied using three-dimensional computed tomography (3DCT). The location of the acetabular deficiency was posterior (37%), anterior (29%), midsuperior (15%), and mixed (19%) (anterosuperior, posterosuperior, and global). Although subtle morphologic changes occurred in the entire acetabulum, the major acetabular deficiency coincided with the direction of the subluxation or dislocation. The location of the acetabular deficiency that develops in cerebral palsy is not always posterosuperior, as suggested by other authors. The pattern of spasticity that results in muscle imbalance around the hip joint and changes in proximal femur architecture causes hip subluxation or dislocation, which may be either, posterior, anterior, or midsuperior. 3DCT studies are required to analyze accurately and understand acetabular deficiency in childhood NMD. These image data also allow more accurate planning for surgery in neuromuscular hip dysplasia.