Animal models and research on preventions and treatments of steroid-associated osteonecrosis of the femoral head

Steroid associated-osteonecrosis (SAON) is non-trauma induced osteonecrosis, which is induced by long-term or high dose of corticosteroid indicated for inflammatory or immune diseases, etc. Subchondral collapse at late stage of SAON usually needs to be treated with joint replacement, while the costs and the prognosis of the surgery are challenge. It is important to perform the fundamental researches on the hip preservation treatments of SAON at early stage, and it is necessary to establish suitable animal models for studying the mechanisms of SAON and evaluating the potential treatments for the SAON. Rabbit SAON model is the most frequently used animal model. It is extensively used in studies on etiology and pathology of SAON. Furthermore, it is possible to evaluate potential drugs for preventing SAON and improving osteogenic repair of mid-stage SAON to prevent joint collapse. Because of bi-pedal, emu has the similar mechanical properties with human. Thus, it can be a suitable animal model for studying preventions and treatments of subchondral collapse of SAON, such as core-decompression with biodegradable materials for bone regeneration. In conclusion, this review updates the current animal SAON models with similar pathology to clinical SAON. These typical models could be used as clinical references for investigating drugs in prevention of early-stage of SAON and biomaterials in hip-preservation surgery for mid-stage of SAON.