[1] Tohoku Univ, Sch Med, Dept Orthopaed Surg, Aoba Ku, Sendai, Miyagi 9808574, Japan
[2] Niigata Univ, Dept Orthopaed Surg, Niigata, Japan
[3] Yonezawa City Hosp, Dept Orthopaed Surg, Yonezawa, Yamagata, Japan
[4] Tohoku Univ Hosp, Dept Pathol, Sendai, Miyagi, Japan