1. Department of Orthopaedic Surgery, Sanggye Paik Hospital, Inje University;
2. Department of Orthopaedic Surgery, Guro-Hospital, Korea University;
3. Department of Orthopaedic Surgery, Kyung Hee Hospital, Kyung Hee University; and
4. Department of Orthopaedic Surgery, Seoul St. Mary's Hospital, Catholic University of Korea, Seoul, Korea