1. Department of Orthopaedics, Cangzhou Central Hospital, Cangzhou, Hebei 061000, P.R. China
2. Department of Surgery (I), Armed Police Engineering University Hospital, Xian, Shaanxi 710000, P.R. China
3. Department of Traumatic Orthopedics, Lanzhou General Hospital of CPLA, Lanzhou, Gansu 730050, P.R. China