Fig. 1.

Treatment strategy for osteonecrosis of the femoral head. Scheme of treatment strategy for osteonecrosis of the femoral head (ONFH) is shown. In daily clinical cases, even if a patient is diagnosed with ONFH, most cases experience femoral head collapse without surgical treatments and finally have to undergo total hip arthroplasty. The ultimate goal for ONFH therapy is to prevent femoral head collapse. Surgical alternatives for preservation include osteotomy and vascularized bone grafting, but the procedures are difficult, technically demanding, and require long-term hospitalization. Therefore, there has been a great desire for a minimally invasive regenerative therapy that can prevent femoral head collapse. Several regenerative treatment options, including cell or stem cell transplantation, artificial bone substitutes, and administration of growth and differentiation factors, have been recently reported