1. The George Institute for Global Health; Musculoskeletal Division; PO Box M201 Missenden Road, Camperdown Sydney NSW Australia 2050
2. VU University Medical Centre; Department of Epidemiology and Biostatistics and the EMGO Institute for Health and Care Research; Amsterdam Netherlands
3. VU University Amsterdam; Department of Health Sciences, Faculty of Earth and Life Sciences; Amsterdam Netherlands
4. Maastricht University Medical Centre; Rehabilitation Medicine Department; Debyelaan 25 PO Box 5800 Maastricht Netherlands 6202 AZ
5. VU University; Department of Health Sciences, EMGO Institute for Health and Care Research; PO Box 7057 Amsterdam Netherlands 1007 MB
6. University of British Columbia; Vancouver BC Canada
7. VU University; Department of Health Sciences, Faculty of Earth and Life Sciences; PO Box 7057 Room U454 Amsterdam Netherlands 1007 MB