VASCULAR DEPRIVATION-INDUCED NECROSIS OF THE FEMORAL-HEAD OF THE RAT - AN EXPERIMENTAL-MODEL OF AVASCULAR OSTEONECROSIS IN THE SKELETALLY IMMATURE INDIVIDUAL OR LEGG-PERTHES DISEASE

The blood supply of rats' femoral heads was severed by cutting the lig amentum teres and stripping the periostium. Histologically, necrosis o f the marrow was apparent on the 2nd postoperative day, necrosis of th e bone on the 5th postoperative day and fibrous ingrowth on the 7th po stoperative day. During the following 5 weeks, progressive resorption of the intertrabecular necrotic debris and necrotic bony trabeculae an d subchondral bone plate and, concurrently, appositional and intramemb ranous new bone formation resulted in remodeling of the femoral heads. In 2 of 7 femoral heads, replacement of the necrotic bone by viable b one was complete at the 42-day postoperative interval. Also, the artic ular cartilage of the deformed and flattened femoral heads was undergo ing degenerative changes. Reduplicating the pathogenically inferred cl inical settings of blood supply deprivation, it is proposed that this model, in a small laboratory animal, satisfies the requirements sought for preclinical studies of treatment modalities of avascular osteonec rosis in man.