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Knee extensor muscle weakness is a risk factor for the development of knee osteoarthritis: an updated systematic review and meta-analysis including 46 819 men and women
  1. Britt Elin Øiestad1,
  2. Carsten B Juhl2,3,
  3. Adam G Culvenor4,
  4. Bjørnar Berg5,
  5. Jonas Bloch Thorlund3,6
  1. 1 Department of Physiotherapy, Faculty of Health Sciences, Oslo Metropolitan University, Oslo, Norway
  2. 2 Department of Physiotherapy and Occupational Theray, Copenhagen University Hospital, Herlev and Gentofte, Denmark
  3. 3 Research Unit for Musculoskeletal Function and Physiotherapy, Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark
  4. 4 La Trobe Sport and Exercise Medicine Research Centre, La Trobe University School of Allied Health Human Services and Sport, Bundoora, Victoria, Australia
  5. 5 Division of Orthopaedic Surgery, Oslo University Hospital, Oslo, Norway
  6. 6 Research Unit for General Practice, Department of Public Health, University of Southern Denmark, Odense, Denmark
  1. Correspondence to Dr Britt Elin Øiestad, Department of Physiotherapy, Faculty of Health Sciences before Oslo Metropolitan University, Oslo, Norway; brielo{at}


Objective To update a systematic review on the association between knee extensor muscle weakness and the risk of incident knee osteoarthritis in women and men.

Design Systematic review and meta-analysis.

Data sources Systematic searches in PubMed, EMBASE, SPORTDiscus, CINAHL, AMED and CENTRAL in May 2021.

Eligible criteria for selecting studies Longitudinal studies with at least 2 years follow-up including baseline measure of knee extensor muscle strength, and follow-up measure of symptomatic or radiographic knee osteoarthritis. Studies including participants with known knee osteoarthritis at baseline were excluded. Risk of bias assessment was conducted using six criteria for study validity and bias. Grading of Recommendations Assessments, Development and Evaluation assessed overall quality of evidence. Meta-analysis estimated the OR for the association between knee extensor muscle weakness and incident knee osteoarthritis.

Results We included 11 studies with 46 819 participants. Low quality evidence indicated that knee extensor muscle weakness increased the odds of symptomatic knee osteoarthritis in women (OR 1.85, 95% CI 1.29 to 2.64) and in adult men (OR 1.43, 95% CI 1.14 to 1.78), and for radiographic knee osteoarthritis in women: OR 1.43 (95% CI 1.19 to 1.71) and in men: OR 1.39 (95% CI 1.07 to 1.82). No associations were identified for knee injured populations except for radiographic osteoarthritis in men.

Discussion There is low quality evidence that knee extensor muscle weakness is associated with incident symptomatic and radiographic knee osteoarthritis in women and men. Optimising knee extensor muscle strength may help to prevent knee osteoarthritis.

PROSPERO registration number CRD42020214976.

  • knee
  • muscle
  • anterior cruciate ligament
  • osteoarthritis
  • quadriceps muscle

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  • Correction notice This article has been corrected since it published Online First. The supplementary file has been updated.

  • Contributors All authors have contributed to the idea of the paper, the interpretation of the analyses and results, and drafting the manuscript. All authors have approved the last version of the manuscript.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.