1. Department of Orthopaedic SurgeryChina–Japan Friendship Hospital, Peking Union Medical College, Chinese Academy of Medical College Beijing China
2. Department of Obstetrics and GynecologyWest China Second University Hospital of Sichuan University Chengdu China
3. Key Laboratory of Birth Defects and Related Diseases of Women and Children of the Ministry of Education Chengdu China
4. Bao Ding Maternal and Children Hospital Baoding China
5. Department of Orthopedics Surgery 81 Group Military Hospital of Chinese PLA Baoding China