1. Department of Orthopaedics, Xijing Hospital, Fourth Military Medical University, Xi'an, P. R. China
2. Department of Orthopaedics, No. 5 Hospital of the PLA, Yinchuan, P. R. China
3. Department of Orthopaedics, Xi'an Air Force Hospital, Xi'an, P.R. China
4. The Second Department of Surgery, No. 518 Hospital of the PLA, Xi'an, P. R. China
5. Department of Orthopaedic Surgery, Lanzhou General Hospital of Lanzhou Military Region, PLA, Lanzhou, P. R. China
6. State Key Laboratory of Military Stomatology, Department of Periodontology, School of Stomatology, Fourth Military Medical University, Xi'an, P. R. China
7. Shaanxi Key Laboratory of Stomatology, Biomaterials Unit, School of Stomatology, Fourth Military Medical University, Xi'an, P. R. China
8. Company Eleven, Brigade of Undergraduates, Fourth Military Medical University, Xi'an, P. R. China
9. Aerospace Medical School, Fourth Military Medical University, Xi'an, P. R. China
10. The First Hospital of Hanbin Area, Ankang, P. R. China
11. Department of Orthopedics, General Hospital of Beijing Military Command, Beijing, P. R. China