Yunfeng Tang1, Dong Wang1, Guanglin Wang2. 1. Department of Orthopedics, Orthopedic Research Institute, West China Hospital, West China Medical School, Sichuan University, #37 Wuhou Guoxue Road, Chengdu, 610041, Sichuan Province, People's Republic of China. 2. Department of Orthopedics, Orthopedic Research Institute, West China Hospital, West China Medical School, Sichuan University, #37 Wuhou Guoxue Road, Chengdu, 610041, Sichuan Province, People's Republic of China. wangglfrank@hotmail.com.