1. Medical Sciences Division, University of Oxford, Oxford, UK
2. Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, UK
3. Department of Plastic and Reconstructive Surgery, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
4. Medical Research Council Population Health Research Unit, University of Oxford, Oxford, UK
5. Clinical Trial Service Unit and Epidemiological Studies Unit, University of Oxford, Oxford, UK