1. Department of Orthopaedic Surgery, Gifu University Graduate School of Medicine, Gifu, Japan
2. Department of Orthopaedic Surgery, Spine Center, Gifu Municipal Hospital, Gifu, Japan
3. Department of Orthopaedic Surgery, Spine Center, Kizawa Memorial Hospital, Minokamo City, Japan
4. Department of Neurosurgery, Kizawa Memorial Hospital, Minokamo City, Japan