1. Cambridge University Hospitals NHS Foundation Trust, Biomedical Campus, Hills Road, Cambridge CB2 0QQ, UK.
2. Royal Devon And Exeter Hospital, Princess Elizabeth Orthopaedic Centre, Barrack Road, Exeter EX2 5DW, UK.
3. South West London Elective Orthopaedic Centre, Dorking Road, Epsom, Surrey KT18 7EG, UK.