1. Department of Traumatic Orthopedics, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, Shandong 250021, P.R. China
2. Department of Orthopedics, Qingyun County People's Hospital, Shandong 253700, P.R. China
3. Department of Pathology, Qingdao Municipal Hospital, Qingdao, Shandong 266011, P.R. China