1. Department of Orthopaedic Surgery, National Hospital Organisation, Osaka Minami Medical Centre, 2-1 Kidohigashi, Kawachinagano, Osaka 586-8521, Japan.
2. Department of Orthopaedic Surgery, Hoshigaoka Koseinenkin Hospital, 4-8-1 Hoshigaoka, Hirakata, Osaka 573-8511, Japan.