Perthes disease conplicated by so called osteochondritis dissecans.

A patient was followed for about 11 years from the onset of Perthes Disease (age 12). The radiographs during the period demonstrated the actual development of a free ossicle which was formed by resorption of a portion of the original femoral head, resulting in a wafer and subsequent enlargement by new bone formation. Changes of a similar nature have been described in idiopathic necrosis of the femoral heads in adults.