1. Department of Anesthesia and Pain Medicine, National Rehabilitation Center, San Jos?, Costa Rica
2. Frankston Pain Management, Melbourne, Australia
3. The Faculty of Medicine, The University of Hong Kong, Hong Kong
4. The Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong
5. Center for Regional Anesthesia and Pain Medicine, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan
6. Center for Regional Anesthesia and Pain Medicine, Chung Shan Medical University Hospital, Taichung, Taiwan
7. The Board of Clinical Research, The Hong Kong Institute of Musculoskeletal Medicine, Hong Kong