[1] Shrewsbury & Telford Hosp NHS Trust, Dept Trauma & Orthopaed Surg, Shropshire, England
[2] Univ Keele, Keele, Staffs, England
[3] Univ Gothenburg, Dept Orthopaed Surg, Molndal Hosp, Gothenburg, Sweden
[4] Gothenburg Univ, Inst Clin Sci, Sahlgrenska Acad, Dept Orthopaed, Gothenburg, Sweden