What condition is suggested by unilateral subacute hip pain and a progressive antalgic gait in a child?

The presentation of unilateral subacute hip pain and a progressive antalgic gait in a child is characteristic of Legg-Calve-Perthes disease. This condition involves avascular necrosis of the femoral head, leading to impaired blood supply and resultant changes in bone structure. Typically, children present with hip pain that is often referred to the knee, and as the condition persists, they may develop a limp due to the discomfort associated with movement.

An antalgic gait develops as the child attempts to minimize pain while walking. Over time, the disease can progress, further exacerbating the limp and the accompanying pain. The subacute nature of the symptoms suggests that the condition has been ongoing for weeks rather than the rapid onset associated with traumatic injuries or acute infections.

In contrast, other conditions like traumatic hip dislocation would present acutely after an injury, transient synovitis is usually characterized by more sudden onset pain and limited range of motion with fever, and osteomyelitis would typically be associated with systemic symptoms such as fever, more acute pain, and possibly localized tenderness or swelling. Therefore, the nature of the symptoms aligns closely with Legg-Calve-Perthes disease.