1. Hirosaki University School of Medicine, 5 Zaifu-cho, Hirosaki, Aomori, 036-8562, Japan
2. Department of Orthopaedic Surgery, Hirosaki University Graduate School of Medicine, 5 Zaifu-cho, Hirosaki, Aomori, 036-8562, Japan
3. Nishikawa Hand Surgery Orthopaedic Clinic, 2-2-12 Waseda, Hirosaki, Aomori, Japan