Study on Autologous Osteoblastic Cells Implantation to Early Stage Osteonecrosis of the Femoral Head

Non-traumatic osteonecrosis is a painful disorder of the hip characterized by a necrosis of the osteomedullary tissue, which leads to subchondral bone collapse and joint destruction. Core decompression is currently the treatment of choice for early stage osteonecrosis of the femoral head. This method consists in decompressing the rigid intra-osseous chamber to promote revascularization, thus halting progression of the disease and stimulating repair. Still this treatment remains highly controversial, since the success rates of the first studies have not been repeated. The exact pathology mechanisms involved in osteonecrosis have not yet be fully elucidated. Several hypotheses have been evoked, including fat embolism, trabecular bone microfractures, microvascular tamponade and, more recently, impaired bone and/or mesenchymal cells recruitment. Three studies have indicated the potential clinical benefits of cell-based approaches for the treatment of osteonecrosis (Hernigou 1997, Hernigou \& Beaujean 2002, Gangji et al. 2004). This is on the basis of these observations that a proprietary population of autologous osteoblastic cells (PREOB®) has been developed. This Phase 3 study aims at demonstrating the efficacy and safety of PREOB® in the treatment of early stage osteonecrosis of the femoral head. More specifically, the purpose of the study is to demonstrate that core decompression/PREOB® implantation into the necrotic lesion is superior to core decompression/placebo implantation in relieving hip symptoms and halting (or reverting) radiological progression of the disease.