1. Department of Orthopaedic Surgery, Toride Kyodo General Hospital, 2-1-1 Hongo, Torideshi-city, Ibaraki-ken pref 302-0022, Japan.
2. Department of Orthopaedic Surgery, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo, 113-8519, Japan.