Perthes' disease and femoroacetabular impingement in a child with proximal femoral focal deficiency.

A girl with known proximal femoral focal deficiency presented with Perthes' disease at 5 years of age. Her treatment involved a Salter osteotomy. This in conjunction with articular incongruence, due to deformity of the femoral head, resulted in mixed type femoroacetabular impingement when she was 10 years old. Surgical hip dislocation and femoral neck osteochondroplasty successfully relieved her symptoms of impingement. This is the first reported case of Perthes' disease in a patient with proximal femoral focal deficiency. The case highlights the importance of thoroughly investigating pain in patients with proximal femoral focal deficiency, a condition which is normally painless. Timely diagnosis of Perthes' disease and containment procedures can prevent collapse of the femoral head and the resultant sequelae. Acetabular over-coverage should be avoided in pelvic osteotomy to prevent the development of femoroacetabular impingement.