Imaging description

A seven-year-old boy presented with right leg pain. Plain film of the hips demonstrated sclerosis, flattening, and fragmentation of the bilateral femoral capital epiphyses as well as shortening and widening of the femoral necks with metaphyseal irregularity including cystic changes. There was involvement of the lateral pillars bilaterally, worse on the right compared to the left (Fig. 84.1). Additionally, slight lateral subluxation of the right hip was demonstrated, consistent with non-containment of the right femoral head within the acetabulum (Fig. 84.1). Findings were considered diagnostic of Legg–Calve–Perthes disease (LCPD).

Importance

LCPD is a condition characterized by idiopathic osteonecrosis of the capital femoral epiphysis. It affects approximately 4 to 15.6 per 100 000 children. Almost all are between three and 12 years old, with the peak incidence occurring around 7 years of age. Boys are affected four to five times more often than girls. Those diagnosed at a younger age typically experience a more benign course than those diagnosed at an older age, who often require increased rates of intervention. Both hips are involved in 10–20% of cases, usually successively rather than simultaneously. It is hypothesized that rapid growth of the bone in relation to the developing blood supply of the secondary ossification centers results in an interruption of adequate blood flow, making these areas prone to avascular necrosis.