1. Department of Orthopedic Surgery, Korea University College of Medicine, Seoul, Korea.
2. Department of Orthopedic Surgery, Rush University Medical Center, Chicago, IL, USA.
3. Department of Orthopedic Surgery, Yonsei University College of Medicine, Seoul, Korea.
4. Department of Orthopedic Surgery, The Second Hospital of Xiangya, Central South University, Changsha, Hunan, P.R. China.