Weijun Wang1, Wenjie Weng2, Yong Qiu3. 1. Department of Joint Surgery, The Affiliated Drum Tower Hospital, Nanjing University Medical School, Nanjing, China. drwilliamwang@163.com. 2. Department of Joint Surgery, The Affiliated Drum Tower Hospital, Nanjing University Medical School, Nanjing, China. 3. Department of Spine Surgery, The Affiliated Drum Tower Hospital, Nanjing University Medical School, Nanjing, China.