Zihao Chen1, Limin Rong2. 1. Department of Spine Surgery, the Third Affiliated Hospital of Sun Yat-sen University, No. 600, Tianhe Road, Guangzhou, 510630, China. 2. Department of Spine Surgery, the Third Affiliated Hospital of Sun Yat-sen University, No. 600, Tianhe Road, Guangzhou, 510630, China. drronglimin@21cn.com.