1. Department of Orthopedic Surgery, Graduate School of Medicine; Chiba University; 1-8-1 Inohana, Chuo-ku Chiba 260-8670 Japan
2. Department of Bioenvironmental Medicine, Graduate School of Medicine; Chiba University; 1-8-1 Inohana, Chuo-ku Chiba 260-8670 Japan
3. Department of Orthopedic Surgery; Chiba Aoba Municipal Hospital; 1273-2 Aoba-cho Cyuou-ku Chiba 260-0852 Japan