1. Department of Spine Surgery, Weifang Traditional Chinese Medicine Hospital, Weifang, Shandong 261041, P.R. China
2. School of Medicine, Shandong University, Jinan, Shandong 250012, P.R. China
3. Department of Spine Surgery, Third Affiliated Hospital of Southern Medical University, Guangzhou, Guangdong 510430, P.R. China