[1] UCL, Div Surg & Intervent Sci, Gower St, London WC1E 6BT, England
[2] Farwaniya Hosp, Dept Surg, Kuwait, Kuwait
[3] Univ Leeds, Leeds Orthopaed Trauma Sci, Leeds, W Yorkshire, England
[4] Leeds Teaching Hosp NHS Trust, Beckett St, Leeds LS9 7TF, W Yorkshire, England
[5] Leeds Inst Rheumat & Muskuloskeletal Med, Leeds, W Yorkshire, England