Tie Liu1, Nicholas Van Halm-Lutterodt1, Qingjun Su1, Yong Hai1. 1. Department of Orthopedics, Beijing Chao-Yang Hospital, Capital Medical University, Room 449, Building D, Gongren Tiyuguan Nan Lu 8#, Beijing Chao-Yang Hospital, Chaoyang District, Beijing, 100020, China.