1. Middlesbrough General Hospital, Ayresome Green Lane, Middlesbrough TS5 5AZ, UK.
2. North Cheshire Hospitals NHS Trust, Warrington General Hospital, Lovely Lane, Warrington, Cheshire WA5 1QG, UK.
3. Department of Orthopaedic Trauma, Royal Infirmary, Lauriston Place, Edinburgh EF3 9YW, UK.
4. Royal Infirmary Edinburgh, Little France, Old Dalkeith Road, Edinburgh EH16 4SU, UK.