A Rabbit Model of Avascular Necrosis of Femoral Head Using Surgical Trauma and Systemic Steroids

Objective: Avascular necrosis of the femoral head (ANFH) is a disease caused by the diminished circulation of the femoral head. The incidence of the disease is increasing and it has heavy socioeconomical burden. Animal models are indispensable for the development of new treatments for bone avascular necrosis. There is not any reliable animal model for simulating the early stages of femoral head osteonecrosis. The aim of this study is to present an animal model of femoral head osteonecrosis induced by systemic steroid use combined with surgery. Methods: Six New Zealand White rabbits were divided into 3 groups. Each group contained 4 femoral heads. For the induction of osteonecrosis, every hip underwent surgical dislocation followed by cauterization of extraperiosteal vessels around the femoral head and ligamentum teres resection. A single dose intramuscular steroid was administered to each rabbit. Rabbits were sacrificed at 2nd, 4th and 6th weeks and femoral heads were sent to histological evaluation. Results: The femoral heads showed typical signs of avascular necrosis at the end of 2nd week. In addition to osteocyte loss and marrow necrosis, there was also new osteoblast formation at the end of 4th week. At the end of 6th week, epiphyseal new bone formation next to large necrotic areas were visible. Conclusion: These results suggest that the single steroid administration combined with hip luxation and cauterization of neck vessels may create femoral head osteonecrosis in rabbits in a repeatable and reliable manner. This model can be presented as an alternative model for the new studies on the treatment of femoral head avascular necrosis in the early stage.