1. Nuffield Department of Primary Care Health Sciences, University of Oxford, Oxford, UK
2. Oxford Trauma Unit, John Radcliffe Hospital, Oxford University Hospital, Oxford, UK
3. Centre for Statistics in Medicine, Oxford Clinical Trials Research Unit, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, UK
4. Orthopaedic Trauma and Limb Reconstruction Unit, St George's University Hospital, London, UK
5. Oxford Trauma and Emergency Care, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, Kadoorie Centre, University of Oxford, Oxford, UK