Department of Orthopaedics, Northumbria Healthcare NHS Foundation Trust, Woodhorn Lane, Ashington, Northumberland, NE63 9JJ, UK. rorymorrison@nhs.net. University of Newcastle, Newcastle upon Tyne, NE1 7RU, UK. rorymorrison@nhs.net. Research and Development, Northumbria Healthcare NHS Foundation Trust, Rake Lane, North Shields, NE29 8NH, UK. Department of Orthopaedics, South Tees Hospitals NHS Foundation Trust, Marton Lane, Middlesbrough, TS4 3BW, UK. Department of Health Sciences, University of York, Heslington, York, YO10 5DD, UK. Faculty of Medical Sciences & NDORMS, University of Oxford, Oxford, OX3 7LD, UK. University of Newcastle, Newcastle upon Tyne, NE1 7RU, UK. Department of Orthopaedics, Northumbria Healthcare NHS Foundation Trust, Woodhorn Lane, Ashington, Northumberland, NE63 9JJ, UK.