1. York Trials Unit, Department of Health Sciences, University of York, York, UK
2. Centre for Health Economics, University of York, York, UK
3. Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, Botnar Research Centre, University of Oxford, Oxford, UK
4. The James Cook University Hospital, South Tees Hospitals NHS Foundation Trust, Middlesbrough, UK