1. Legg-Calve-Perthes disease
Got a kid who complains of pain anywhere from hip to knee and has limited hip motion? It might be Legg-Calve-Perthes disease. This disease occurs when blood supply to the femoral head (ball joint) is lost and the bone starts to die. The bone eventually breaks apart and loses the ball shape. After the blood supply is restored, the bone rebuilds itself, but no longer smooth and round.
There are treatments that will preserve the femoral joint’s shape, so talk with your pediatrician.