1. Department of Trauma Orthopedics, Ningbo No. 6 Hospital, Ningbo, Zhejiang 315000, P.R. China
2. Department of Neurology, The Affiliated Hospital of Medical School of Ningbo University, Ningbo, Zhejiang 315000, P.R. China
3. Department of Spine, Ningbo No. 6 Hospital, Ningbo, Zhejiang 315000, P.R. China