1. Department of Epidemiology and Preventive Medicine, University of Maryland School of Medicine, Baltimore, USA
2. National Study Center for Trauma & EMS, 701 W. Pratt Street, Suite 590, Baltimore, MD 21201, USA
3. Department of Kinesiology, University of Maryland, College Park, MD, USA
4. Center for Orthopedics, Dongfang Hospital, Beijing, China
5. Wangjing Hospital of China Academy of Chinese Medical Sciences, Beijing, China
6. Health Outcome Management, LLC, USA
7. Welch Center for Prevention, Epidemiology & Clinical Research, Johns Hopkins Medical Institutions, Baltimore, MD, USA