1. Department of Orthopaedic Surgery, Kanto Teishin Hospital, 5-9-22 Higashi Gotanda Shinagawa-ku, Tokyo, Japan.
2. Department of Orthopaedic Surgery, Faculty of Medicine, University of Tokyo, 7-3-1 Hongo Bunkyo-ku, Tokyo, Japan.
3. Ebara Municipal Hospital, 4-5-10 Higashi Yukigaya Oota-ku, Tokyo, Japan.