1. Leicester Royal Infirmary, Infirmary Square, Leicester LE1 5WW, UK
2. Leeds General Infirmary, Great George Street, Leeds LS1 3EX, UK.
3. Derriford Hospital, Derriford, Plymouth PL6 8DH, UK.
4. School of Health and Social Sciences, Coventry University, Priory Street, Coventry CV1 5FB, UK.
5. Department of Public Health and Epidemiology
6. Department of Orthopaedic Trauma, University of Leicester, Leicester LE1 7RH, UK.
7. Department of Orthopaedics, University of Newcastle upon Tyne, Newcastle upon Tyne, UK.