A disorder of the hip in young children in which idiopathic juvenile avascular necrosis of the femoral head leads to a cascade of complicating factors and subchondral fracture of the head. This initiates bone resorption and can lead to collapse of the femoral head. This irregularity may lead, much later, to subsequent degenerative joint disease. The most common presentation is an insidious onset of a limp.
Pain can be either absent or mild in nature.
When pain is present, it is usually activity related and relieved by rest. Pain is usually in the groin area, but can be referred to the anteromedial thigh or knee. Physical exam is notable for limited abduction and internal rotation. Atrophy of the thigh, calf, and buttock can be present from disuse. Leg length inequality is a late finding.