[1] St Georges Healthcare NHS Trust, Dept Trauma & Orthopaed, London SW17 0QT, England
[2] Warrington Gen Hosp, Dept Trauma Orthopaed, Warrington WA5 1QG, Cheshire, England
[3] Warrington Gen Hosp, Warrington WA5 1QG, Cheshire, England
[4] Univ Salford, Dept Sports Med, Luton, Beds, England
[5] Aintree Teaching Hosp, Univ Hosp, NHS Fdn Trust, Dept Trauma & Orthopaed, Liverpool L9 7AL, Merseyside, England