1. Department of Sports Medicine; Research Center of Sports Medicine, Xiangya Hospital, Central South University; Changsha 410008 Hunan, P.R. China
2. Department of Spine Surgery; Xiangya Hospital, Central South University; Changsha Hunan, P.R. China
3. Department of Orthopaedics & Traumatology; The Chinese University of Hong Kong; Hong Kong SAR P.R. China