[1] Royal Natl Orthopaed Hosp, Dept Histopathol, Stanmore HA7 4LP, Middx, England
[2] Royal Natl Orthopaed Hosp, Dept Radiol, Stanmore HA7 4LP, Middx, England
[3] UCL, Wolfson Inst Biomed Res, London, England
[4] UCL, Inst Orthopaed & Musculoskeletal Sci, Stanmore, Middx, England