1. Department of Orthopedic Surgery, Okayama Rosai Hospital, 1-10-25 Chikkomidorimachi, Minami Ward Okayama, Okayama 702-8055, Japan
2. Department of Orthopedic Surgery, Sir Ganga Ram Hospital, Rajinder Nagar, New Delhi 110060, India
3. Spinal Disorder Center, Fujieda Heisei Memorial Hospital, 123-1 Mizuue Fujieda, Shizuoka 426-8662, Japan
4. Department of Neurosurgery, Okayama Rosai Hospital, 1-10-25 Chikkomidorimachi, Minami Ward Okayama, Okayama 702-8055, Japan