Knee extensor muscle weakness may be a risk factor for osteoarthritis

1. Low quality evidence demonstrates that knee extensor muscle weakness increased the odds of symptomatic and radiographic knee osteoarthritis in men and women.

2. In women with a previous knee injury, low quality evidence shows no association between knee extensor muscle weakness and symptomatic and radiographic tibiofemoral osteoarthritis.

Evidence Rating Level: 2 (Good)

Knee osteoarthritis is a leading cause of pain and disability in older adults with no curative options. One non-pharmacologic option is to address knee extensor muscle weakness which may help to regulate joint loads critical to maintaining the homeostasis of cartilage. The objective of the present systematic review and meta-analysis was to update a prior study from 2015 which investigated the association between knee extensor muscle weakness and the risk of incident symptomatic or radiographic patellofemoral or tibiofemoral osteoarthritis in women and men.

From 1331 screened records, 11 studies (n=46 819) were included in an updated search in May 2021. Longitudinal studies (with at least 2 year follow up) were included if they assessed knee extensor muscle strength at baseline and assessed structural or symptomatic knee osteoarthritis. Studies were excluded if participants had known symptomatic or radiographic knee osteoarthritis at baseline or had rheumatologically diseases. Quality of the evidence was assessed using the Grading of Recommendations Assessments, Development and Evaluation (GRADE).

Results demonstrated low quality evidence that knee extensor muscle weakness increased the odds of symptomatic and radiographic knee osteoarthritis in men and women. Furthermore, in women with a previous knee injury, low quality evidence shows no association between knee extensor muscle weakness and symptomatic and radiographic tibiofemoral osteoarthritis. However, the present was limited due to considerable heterogeneity included in the studies with respect to study populations and clinical definitions. Nonetheless, the current findings suggest that improving knee extensor strength may help prevent knee osteoarthritis.

Click to read the study in British Journal of Sports Medicine 

Image: PD

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