1. Royal Free Hospital and The Wellington Knee Unit, Wellington Place, St John’s Wood, London NW8 9LE, UK.
2. Department of Trauma & Orthopaedics, Watford General Hospital, Watford, Hertfordshire WD18 0HB, UK.
3. Department of Orthopaedics, Royal Free Hospital, Pond Street, London NW3 2QG, UK.