1. Department of Orthopaedic Surgery, Seoul National University Hospital, 28 Yeongon-dong, Jongno-gu, 110-744 Seoul, Korea.
2. Department of Orthopaedic Surgery, Inje University Sanggye Paik Hospital, Sanggye-dong, Nowon-gu, 139-707 Seoul, Korea.
3. Department of Orthopaedic Surgery, Jeju University Hospital, Ara 1-dong, 690-767 Jeju-do, Korea.