A 7-year-old child is brought to the clinic by parents who report the child has been limping and complaining of hip pain for the past 2 weeks. Which assessment finding would be most characteristic of Legg-Calvé-Perthes disease?

Legg-Calvé-Perthes disease typically presents with a painless or mild pain limp, along with limited hip abduction and internal rotation due to avascular necrosis of the femoral head. Other options describe findings more characteristic of acute conditions like trauma or infection.

Clinical Presentation of Legg-Calvé-Perthes Disease

The most characteristic assessment finding for Legg-Calvé-Perthes disease (LCPD) in a school-aged child is a painless limp with limited hip abduction and internal rotation. LCPD is an idiopathic avascular necrosis of the capital femoral epiphysis that typically presents with an insidious onset, often leading to a delay in diagnosis . The classic clinical picture involves a child, most commonly between the ages of 5 and 7 years, who develops a limp that may be intermittent and is frequently described as painless, although mild activity-related pain in the hip, thigh, or knee can be present . The pathophysiologic process begins with an interruption of the blood supply to the capital femoral epiphysis, initiating a sequence of ischemia, revascularization, and reossification . During the revascularization phase, the subchondral bone becomes mechanically weakened, which can lead to a subchondral fracture and subsequent femoral head deformity . This structural compromise and the associated synovitis directly restrict the joint's range of motion, manifesting as a characteristic limitation in hip abduction and internal rotation. The limp arises from both the mechanical restriction and subtle leg-length discrepancy that can develop.

The other options describe findings that are less characteristic of the typical insidious presentation of LCPD. Severe acute pain with an inability to bear weight is more indicative of an acute fracture, septic arthritis, or transient synovitis with severe spasm. A hip deformity with external rotation and shortening is a late finding that may develop if significant femoral head deformity and collapse occur, but it is not the most characteristic initial presentation. Swelling and warmth over the hip joint are cardinal signs of an acute inflammatory or infectious process, such as septic arthritis, rather than the avascular, non-infectious pathology of LCPD.