[1] Univ Leeds, Sch Med, Acad Dept Trauma & Orthopaed, Leeds LS2 9LU, England
[2] Salford Royal NHS Fdn Trust, Trauma Audit & Res Network, Summerfield House, Salford M6 8HD, England
[3] Univ Sheffield, Ctr Urgent & Emergency Care Res, Sch Hlth & Related Res ScHARR, Sheffield S1 4DA, England
[4] Chapel Allerton Hosp, NIHR Leeds Biomed Res Ctr, Leeds LS2 9LU, England