1. Department of Anesthesiology and Pain Relief Center, The University of Tokyo Hospital, Tokyo 113-8655, Japan
2. Department of Pain and Palliative Medicine, The University of Tokyo Hospital, Tokyo 113-8655, Japan
3. Department of Orthopaedic Surgery, The University of Tokyo Hospital, Tokyo 113-8655, Japan
4. Department of Orthopaedic Surgery, Jichi University, Graduate School of Medicine, Tochigi, Japan