Joint-preserving regenerative therapy for patients with early-stage osteonecrosis of the femoral head.

Osteonecrosis of the femoral head is an intractable disease often occurring in patients aged 30-40 years that can cause femoral head collapse, pain, and gait disturbance. Background factors, including corticosteroid use, alcohol intake, and idiopathic causes, have been indicated. It is estimated that 70-80 % of osteonecrosis patients experience femoral head collapse, for which total hip arthroplasty is considered the most effective treatment, even in young patients. Thus, there is a crucial need for developing a minimally invasive regenerative therapy as a preventive surgery for femoral head collapse: this has been an important area of research in the past decades. Core decompression, the most popular minimally invasive surgery for osteonecrosis of the femoral head, has been used for a long time; however, it has been insufficient to prevent femoral head collapse. For further improvement in therapeutic efficacy, cell transplantation and the use of artificial bone and growth factors have been proposed in addition to core decompression. Since 2000, newer therapies such as autologous bone marrow cell transplantation and the embedding of metal implant rods have been developed in Europe and the USA; however, these approaches have yet to become a global standard. This practical review summarizes applied state-of-the-art regenerative therapy-based core decompression. We introduce the clinical application of recombinant human fibroblast growth factor (rhFGF)-2-impregnated gelatin hydrogel for patients with precollapse osteonecrosis of the femoral head. Radiography and computed tomography have confirmed bone regeneration inside the femoral heads around the region of rhFGF-2 gelatin hydrogel administration. With further development, the minimally invasive method, which can be expected to promote bone regeneration in necrotic areas, could become a useful early-stage treatment for osteonecrosis of the femoral head. Patients can resume their daily routine soon after surgery, and the procedure is inexpensive. As such, it is a promising regenerative therapy that can be actively employed in osteonecrosis of the femoral head before femoral head collapse.