Ma et al. performed a prospective, double-blinded, randomised and controlled study of the effect of bone-marrow buffy coat grafting. Forty-five patients (53 hips) with Ficat stage I to stage III (Ficat, 1985) osteonecorosis on femoral head were recruited. The hips were allocated to the control group (core decompression+autologous bone graft) or treatment group (core decompression+autologous bone graft with bone-marrow buffy coat). After 24 months, there was significant relief of pain and clinical joint symptoms in the treatment group. In addition, 33.3% of hips in the control group deteriorated to the next stage, whereas only 8% in the treatment group had further deterioration. The non-progression rates for stage I/II hips were 100% in the treatment group and 66.7% in the control group.