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Open Access Study protocol

The DAMASK trial protocol: a pragmatic randomised trial to evaluate whether GPs should have direct access to MRI for patients with suspected internal derangement of the knee

Stephen D Brealey1*, Christine Atwell2, Stirling Bryan3, Simon Coulton4, Helen Cox1, Ben Cross1, Fiona Fylan5, Andrew Garratt6, Fiona J Gilbert7, Maureen GC Gillan7, Maggie Hendry8, Kerenza Hood9, Helen Houston2, David King10, Veronica Morton1, Jo Orchard4, Michael Robling2, Ian T Russell11, David Torgerson1, Valerie Wadsworth1 and Clare Wilkinson8

Author Affiliations

1 Department of Health Sciences, York Trials Unit, Seebohm Rowntree Building, University of York, Heslington, York YO10 5DD, UK

2 Department of General Practice, Cardiff University, Neuadd Meirionydd, Heath Park, Cardiff, CF14 4YS, UK

3 Health Services Management Centre, University of Birmingham, Park House, 40 Edgbaston Park Road, Birmingham, West Midlands, B15 2TT, UK

4 Department of Health Sciences, Seebohm Rowntree Building, University of York, Heslington, York YO10 5DD, UK

5 Department of Psychology, Leeds Metropoitan University, Leeds LS1 3HE, UK

6 Institute of Health Management and Health Economics, University of Oslo, PO Box 1089, Blindern, NO-0317 Oslo, Norway

7 Department of Radiology, Lilian Sutton Building, University of Aberdeen, Foresterhill, Aberdeen, AB25 2ZD, UK

8 Cardiff University School of Medicine, North Wales Clinical School, Gwenfro Building, Unit 5, Wrexham Technology Park, Wrexham, LL13 7YP, UK

9 South East Wales Trials Unit, Centre for Health Sciences Research, Cardiff University, Neuadd Meirionydd, Heath Park, Cardiff, CF14 4YS, UK

10 X-ray Department, York Hospital, Wigginton Road, York, YO31 8HE, UK

11 Institute of Medical and Social Care Research, Brigantia Building, Penrallt Road, University of Wales Bangor, Gwynedd, LL57 2AS, UK

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BMC Health Services Research 2006, 6:133  doi:10.1186/1472-6963-6-133

Published: 13 October 2006



Though new technologies like Magnetic Resonance Imaging (MRI) may be accurate, they often diffuse into practice before thorough assessment of their value in diagnosis and management, and of their effects on patient outcome and costs. MRI of the knee is a common investigation despite concern that it is not always appropriate. There is wide variation in general practitioners (GPs) access to, and use of MRI, and in the associated costs. The objective of this study was to resolve uncertainty whether GPs should refer patients with suspected internal derangement of the knee for MRI or to an orthopaedic specialist in secondary care.


The design consisted of a pragmatic multi-centre randomised trial with two parallel groups and concomitant economic evaluation. Patients presenting in general practice with suspected internal derangement of the knee and for whom their GP was considering referral to an orthopaedic specialist in secondary care were eligible for inclusion. Within practices, GPs or practice nurses randomised eligible and consenting participants to the local radiology department for an MRI examination, or for consultation with an orthopaedic specialist. To ensure that the waiting time from GP consultation to orthopaedic appointment was similar for both trial arms, GPs made a provisional referral to orthopaedics when requesting the MRI examination. Thus we evaluated the more appropriate sequence of events independent of variations in waiting times. Follow up of participants was by postal questionnaires at six, twelve and 24 months after randomisation. This was to ensure that the evaluation covered all events up to and including arthroscopy.


The DAMASK trial should make a major contribution to the development of evidence-based partnerships between primary and secondary care professionals and inform the debate when MRI should enter the diagnostic pathway.