Fifteen patients with ONFH at Ficat Stage III¬-IV and 15 patients with osteoarthritis will undergo total hip replacement. Femoral head specimens will be collected and ex vivo specimens numbered. Using RT-PCR, Runx2, BMP-2, BMP-7 and osteoprotegerin, mRNA expression levels will be quantitatively analyzed. Osteocalcin immunoreactivity will be detected using immunohistochemical staining. Professional staff, blinded to grouping, will perform outcome index detection and statistical analysis.