[1] Univ Oxford NHS Fdn Trust, Nuffield Orthopaed Ctr, Windmill Rd, Oxford OX3 7LD, England
[2] Univ Oxford NHS Fdn Trust, John Radcliffe Hosp, Headley Way, Oxford OX3 9DU, England
[3] Surrey & Sussex Healthcare NHS Trust, East Surrey Hosp, Canada Ave, Redhill RH1 5RH, Surrey, England
[4] Univ Oxford, Nuffield Dept Orthopaed Rheumatol & Musculoskelet, Oxford OX3 7LD, England
[5] La Paz Univ, Hosp IdiPaz, Dept Orthopaed Surg, Paseo Castellana 261, Madrid 28046, Spain