1. Department of Anesthesiology, Qingdao No. 6 People's Hospital, Qingdao, Shandong 266033, P.R. China
2. Department of Orthopedics, Qingdao No. 6 People's Hospital, Qingdao, Shandong 266033, P.R. China
3. Department of Functional Inspection, Qingdao Haici Medical Treatment Group, Qingdao, Shandong 266033, P.R. China