Open Access Open Badges Research article

What is the clinical and ethical importance of incidental abnormalities found by knee MRI?

Rebecca Grainger12, Stephen Stuckey3, Richard O'Sullivan4, Susan R Davis5, Peter R Ebeling6 and Anita E Wluka78*

Author Affiliations

1 Department of Medicine, Wellington School of Medicine, University of Otago, 23A Mein St, Newtown, Wellington South 6021, New Zealand

2 Malaghan Institute of Medical Research, Kelburn Parade, Wellington 6012, New Zealand

3 Department of Diagnostic Imaging, Southern Health, Clayton Road, Clayton, Victoria, 3168, Australia

4 MRI Unit, Epworth Hospital, 89 Bridge St, Richmond Victoria, 3121, Australia

5 National Health and Medical Research Council of Australia Centre of Clinical Research Excellence for the Study of Women's Health Program, Department of Medicine, Monash University Medical School, Alfred Hospital, Melbourne, Victoria, 3004, Australia

6 Departments of Medicine (RMH/WH) and Endocrinology, University of Melbourne, Western Hospital, University of Melbourne, Cnr Marian and Eleanor Streets, Footscray, Victoria, 3011, Australia

7 Baker Heart Research Institute, AMREP, Commercial Road, Melbourne, Victoria, 3004, Australia

8 Department of Epidemiology and Preventive Medicine, Monash University, Alfred Hospital, Commercial Road, Melbourne, Victoria, 3004, Australia

For all author emails, please log on.

Arthritis Research & Therapy 2008, 10:R18  doi:10.1186/ar2371

Published: 5 February 2008



Magnetic resonance imaging (MRI) is increasingly used to examine joints for research purposes. It may detect both suspected and unsuspected abnormalities. This raises both clinical and ethical issues, especially when incidental abnormalities are detected. The prevalence of incidental, potentially clinically significant abnormalities identified by MRI and their clinical significance in a population undergoing knee MRI in research studies are unknown.


We examined the prevalence of such lesions in healthy asymptomatic adults and those with symptomatic knee osteoarthritis (OA) undergoing knee MRI with limited sequences for the purpose of research. The MRI findings in 601 asymptomatic subjects and 132 with knee OA who underwent at least one limited knee MRI scan for cartilage volume measurement were examined by an MRI radiologist for the presence of potentially clinically significant abnormalities.


These were present in 2.3% of healthy and 2.3% of OA subjects. All required further investigation to exclude non-benign disease, including four with bone marrow expansion (0.7%), requiring further investigation and management. A single potentially life-threatening lesion, a myeloma lesion, was identified in a subject with symptomatic knee OA on their second MRI scan in a longitudinal study.


As musculoskeletal MRI is increasingly used clinically and for research purposes, the potential for detecting unsuspected abnormalities that require further investigation should be recognized. Incorporating a system to detect these, to characterize unexpected findings, and to facilitate appropriate medical follow-up when designing studies using this technology should be considered ethical research practice.