Delay of total hip arthroplasty to advanced stage worsens post-operative hip motion in patients with femoral head osteonecrosis.

The progression of ONFH negatively affected post-operative hip ROM as well as baseline hip ROM at the time of THA. Surgeons should consider a delay of THA negatively affects the hip ROM after the arthroplasty, when they determine the treatment modality for ONFH patients.