1. Leighton Research Unit, Department of Surgery, Leighton Hospital, Mid Cheshire NHS Trust, Crewe, UK
2. Institute for Science and Technology in Medicine, Keele University, Keele, UK
3. Research and Development Office, Leighton Hospital, Mid Cheshire NHS Trust, Crewe, UK
4. Department of Surgery, University Hospital North Staffordshire, Stoke-on-Trent, UK