Tianbing Wang1, Baoguo Jiang2. 1. Trauma Medicine Center, Department of Trauma and Orthopaedics, Peking University People's Hospital, Beijing 100044, China. 2. Trauma Medicine Center, Department of Trauma and Orthopaedics, Peking University People's Hospital, Beijing 100044, China. Electronic address: jiangbaoguo@vip.163.com.