1. Winford Unit, Avon Orthopaedic Centre, Southmead Hospital, Southmead Road, Westbury-on-Trym, Bristol BS10 5BN, UK.
2. Prince of Wales Private Hospital, Barker Street, Randwick, New South Wales, 2031, Australia.
3. Department of Orthopaedics Bristol Royal Infirmary, Upper Maudlin Street, Bristol BS2 8HW, UK.