1 Physiotherapy Research Unit, Nuffield Orthopaedic Centre, Oxford University Hospitals NHS Foundation Trust, Oxford, OX3 7HE, UK. Electronic address: Cathy.Jenkins@ouh.nhs.uk.
2 Consultant Orthopaedic Surgeon, Nuffield Orthopaedic Centre, Oxford University Hospitals NHS Foundation Trust, Oxford, OX3 7HE, UK.
3 Consultant Orthopaedic Surgeon, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, Nuffield Orthopaedic Centre, Oxford University Hospitals NHS Foundation Trust, Oxford, OX3 7HE, UK.
4 Clinical Director, Professor of Physiotherapy, Nuffield Orthopaedic Centre, Oxford University Hospitals NHS Foundation Trust, Oxford, OX3 7HE, UK.