1. Department of Orthopedics; China-Japan Union Hospital of Jilin University; Changchun Jilin China
2. Department of Anatomy and Neurobiology; School of Basic Medical Science Central South University; Changsha China
3. Department of Clinical Epidemiology; the First Hospital of Jilin University; Changchun China
4. Department of Spine Surgery; the First Hospital of Jilin University; Changchun China