1. Blackpool Victoria Hospital, Whinney Heys Road, Blackpool FY3 8NR, UK.
2. Doncaster Royal Infirmary, Armthorpe Road, Doncaster DN2 5LT, UK.
3. Orthopaedic Department, University Hospital Aintree, Longmoor Lane, Liverpool L9 7AL, UK.
4. Knee Reconstruction Unit, Northern General Hospital, Herries Road, Sheffield S5 7AU, UK.
5. Orthopaedic Department, Wirral University Teaching Hospital NHS Foundation Trust, Arrowe Park Hospital, Arrowe Park Road, Upton, Wirral CH49 5PE, UK.