[1] Tazawako Hosp, Dept Orthoped Surg, Akita 0141201, Japan
[2] Akita Univ, Grad Sch Med, Dept Orthoped Surg, Akita 0108543, Japan
[3] Akita Univ Hosp, Dept Rehabil Med, Akita 0108543, Japan
[4] Akita Univ, Fac Engn Sci, Dept Mech Engn, Akita 0108502, Japan