1. Department of Orthopedic Surgery Peking Union Medical College Hospital Peking Union Medical College Chinese Academy of Medical Science Beijing China
2. Division of Joint Osteopathy and Traumatology Center of Orthopedics Surgery Guangdong Provincial People's Hospital Guangdong Academy of Medical Sciences School of Medicine South China University of Technology Guangzhou China
3. Office of Clinical Epidemiology, Obstetrics and Gynecology Hospital of Fudan University Shanghai China