1. Department of Orthopaedic Surgery, Clinical Research Center, National Hospital Organization Kyushu Medical Center , Fukuoka, Japan
2. Department of Orthopaedic Surgery, Kyushu University Beppu Hospital , Oita, Japan
3. Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kyushu University , Fukuoka, Japan
4. Department of Orthopaedic Surgery, Saga-ken Medical Centre Koseikan , Saga, Japan