1. The Hull York Medical School, Hertford Building, University of Hull, HU6 7RX, United Kingdom
2. Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, OX3 7LD, United Kingdom
3. Division of Trauma and Orthopaedics, University of Cambridge, Addenbrooke's Hospital, Cambridge, CB2 2QQ, United Kingdom