1. Department of Orthopedic Surgery, Xijing Hospital, The Fourth Military Medical University, Xi'an, Shaanxi 710032, P.R. China
2. Department of Orthopaedics, Chinese PLA General Hospital, Beijing 100853, P.R. China
3. Department of Orthopedic Surgery, Honghui Hospital, College of Medicine, Xi'an Jiaotong University, Xi'an, Shaanxi 710049, P.R. China