1. Research and Education South West London Elective Orthopaedic Centre, Dorking Road, Epsom, Surrey KT18 7EG, UK.
2. Epsom and St. Helier, University Hospitals NHS Trust, Wrythe Lane, Carshalton, Surrey SM5 1AA, UK.
3. Luton and Dunstable Hospital NHS Trust, Lewsey Road, Luton LU4 0DZ, UK.