1. Department of Orthopaedic Surgery, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan
2. Department of Orthopaedic Surgery, Fujioka General Hospital, Fujioka, Gunma, Japan
3. Department of Orthopaedic Surgery, Gunma Saiseikai Maebashi Hospital, Maebaashi, Gunma, Japan
4. Department of Orthopaedic Surgery, Japan Redcross Society Fukaya Redcross Hospital, Fukaya, Saitama, Japan.