This hip condition, also known as Perthes disease, affects children between 5 and 12 years of age. For unknown reasons, the child's femoral head – the top of the femur (thighbone) which meets the pelvis to form the hip joint – loses its blood supply. This causes the head to die and then regrow, usually over a period of two years.

Treatments for Perthes disease include anti-inflammatory medications such as ibuprofen, avoiding running and jumping, and in some cases, a total hip replacement.