Susan Hesni1, Daniel Lindsay2, Asif Saifuddin3. 1. Department of Radiology, Royal National Orthopaedic Hospital (RNOH), Stanmore, UK. susan.hesni@nhs.net. 2. Department of Histopathology, Royal National Orthopaedic Hospital (RNOH), Stanmore, UK. 3. Department of Radiology, Royal National Orthopaedic Hospital (RNOH), Stanmore, UK.