Proximal femoral focal deficiency.

Proximal femoral focal deficiency, a distinct clinical and radiographic entity that results in leg length discrepancy, has received little attention in the radiographic literature. Thirteen patients were studied and the degree of deficiency established using radiographic criteria. The full extent of hip instability often could not be ascertained on radiographs obtained during the first year of life. Hip arthrograms combined with cine radiography can establish the presence of an unossified femoral head and aid in evaluating the degree of hip instability. Unlike other causes of leg length discrepancy, such as congenital idiopathic coxa vara, proximal femoral focal deficiency is often associated with other congenital bony anomalies, most commonly ipsilateral absent or hypoplastic fibula.