1. Warwick Clinical Trials Unit, Warwick Medical School, University of Warwick, Coventry, UK; University Hospitals Coventry and Warwickshire NHS Trust, Coventry, UK
2. Oxford Trauma, Nuffield Department of Orthopaedics, Rheumatology & Musculoskeletal Sciences, University of Oxford, Oxford, UK
3. Statistics and Epidemiology Unit, Warwick Medical School, University of Warwick, Coventry, UK
4. University of Oxford Oxford Trauma, Nuffield Department of Orthopaedics, Rheumatology & Musculoskeletal Sciences, University of Oxford, Oxford, UK