1. Department of Orthopaedics and Traumatology, University of Hong Kong, Hong Kong, Hong Kong
2. Department of Orthopedic Surgery, Rush University Medical Center, Chicago, Illinois, USA
3. International Spine Research and Innovation Initiative, RUSH University Medical Center, Chicago, Illinois, USA
4. Medical Research Center Oulu, Oulu University Hospital and University of Oulu, Oulu, Finland
5. Finnish Institute of Occupational Health, Oulu, Finland