1. Department of Nursing, The People's Hospital of YueChi County, Guang'an, Sichuan 638373, P.R. China
2. Department of Orthopedic Surgery, The People's Hospital of RenShou County, Meishan, Sichuan 620500, P.R. China
3. Department of Orthopedic Surgery, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, P.R. China