[1] Hokkaido Univ, Sch Med, Dept Sports Med & Joint Reconstruct Surg, Kita Ku, Sapporo, Hokkaido 0608636, Japan
[2] Hokkaido Univ, Sch Med, Dept Orthopaed, Kita Ku, Sapporo, Hokkaido 0608638, Japan
[3] Hokkaido Univ, Sch Med, Dept Mol Biochem, Kita Ku, Sapporo, Hokkaido 0608638, Japan
[4] Chiba Univ, Grad Sch Med, Dept Med Immunol, Chiba 2608670, Japan