1. Department of Obstetrics and Gynecology, Central Hospital Affiliated to Shenyang Medical College, Shenyang, Liaoning 110024, P.R. China
2. Fourth Department of Orthopedic Surgery, Central Hospital Affiliated to Shenyang Medical College, Shenyang, Liaoning 110024, P.R. China
3. Department of Orthopedic Surgery, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang 310003, P.R. China