1. Newcastle University School of Medicine, Newcastle University, Cookson Building, Newcastle Upon Tyne NE2 4HH, UK
2. Trauma Audit and Research Network, University of Manchester, Salford Royal NHS Foundation Trust, Salford M6 8HD, UK
3. School of Health and Related Research (ScHARR), University of Sheffield, Regent Court, 30 Regent Street, Sheffield S1 4DA, UK
4. Department of Trauma and Orthopaedics, Sunderland Royal Hospital, Kayll Road, Sunderland SR4 7TP, UK
5. Department for Care of the Elderly, Sunderland Royal Hospital, Kayll Road, Sunderland SR4 7TP, UK
6. Department of Trauma and Orthopaedics, James Cook University Hospital, Marton Road Middlesbrough, TS4 3BW, UK
7. York Clinical Trials Unit, Department of Health Sciences, University of York, Seebohm Rowntree Building, Heslington, York YO105 DD, UK