1 London School of Surgery, Stewart House, Russell Square, London, UK.
2 Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences (NDORMS), Botnar Research Centre, University of Oxford, Oxford, UK.
3 Plastic and Reconstructive Surgery Department, Imperial College NHS Foundation Trust, Praed Street, London, UK.
4 Plastic and Reconstructive Surgery Department, Royal Free London NHS Foundation Trust, Pond Street, London, UK. Electronic address: Justin.wormald@ndorms.ox.ac.uk.