Tianhang Xie1, Xi Yang1, Yueming Song2. 1. Department of Orthopedics, West China Hospital/West China School of Medicine, Sichuan University, 37# Wuhou Guoxue Road, Chengdu, 610041, People's Republic of China. 2. Department of Orthopedics, West China Hospital/West China School of Medicine, Sichuan University, 37# Wuhou Guoxue Road, Chengdu, 610041, People's Republic of China. sym_cd@163.com.