1. Department of Orthopaedic Surgery; The Third Hospital of Hebei Medical University; Shijiazhuang Hebei P. R. China
2. Hebei Bone Research Institute, Key Laboratory of Biomechanics of Hebei Province; Shijiazhuang Hebei P. R. China
3. Department of Epidemic of Disease and Health Statistics; Shijiazhuang Hebei P. R. China