Department of Orthopedic Surgery (Spine Division), 1st People's Hospital of Taicang City, South Changshen Road 58#, Taicang, 215400, Jiangsu Province, China. Division of Rheumatology, Huashan Hospital, Shanghai Medical College, Fudan University, 12 Wulumuqizhong Road, 200040, Shanghai, China. Department of Orthopedic Surgery (Spine Division), 1st People's Hospital of Taicang City, South Changshen Road 58#, Taicang, 215400, Jiangsu Province, China. zryang@outlook.com.