Knee muscle strength as a mediator of sex differences in incident knee osteoarthritis
Main finding · Incident lateral radiographic KOA (knees without radiographic KOA at baseline)Result — go to the resultOdds ratio 1.72 95% CI 1.28–2.31Authors' conclusion
The lateral radiographic and symptomatic KOA risk is higher in females than males, partly mediated by lower flexor and extensor strength.
Study context
- Population
- Knees without radiographic or symptomatic knee OA at baseline, Osteoarthritis Initiative participants aged 45–79 years5,126 knees without radiographic knee osteoarthritis (KOA)
- Participants
- 3,056 participants
- Exposure
- Females vs males, with knee flexor and extensor strength as mediators
- Outcome
- Incident lateral radiographic and symptomatic knee OA, and mediation by knee flexor and extensor strength (isometric, normalized to BMI)
- Follow-up
- 8 years
Methodological detailsmediation analysis, marginal structural models, longitudinal prospective (Osteoarthritis Initiative)
- Mediation analysis
- Marginal structural models
- Longitudinal prospective (Osteoarthritis Initiative)
Main finding
As reported in the abstract
Incident lateral radiographic KOA (knees without radiographic KOA at baseline)
Odds ratio
1.72
95% CI 1.28–2.31
By group
Femalesvs Males
OR 1.72 (95% CI 1.28–2.31)
- Indirect effect of female sex via flexor strength, OR
- 1.14 (1.04 to 1.26) (95% CI)
- Indirect effect of female sex via extensor strength, OR
- 1.16 (1.05 to 1.27) (95% CI)
- Direct effect, not mediated through flexor strength, OR
- 1.48 (1.01 to 1.95) (95% CI)
- Direct effect, not mediated through extensor strength, OR
- 1.46 (1.01 to 1.92) (95% CI)
- Proportion of total effect of sex mediated by knee flexor strength
- 31.1%
- Proportion of total effect of sex mediated by knee extensor strength
- 33.9%
Observational data: associations, not effects.
Further findings
Incident lateral symptomatic knee OA
- Similar results also observed
- 6,773 knees from 3,720 participants without symptomatic KOA
Original publication
Knee muscle strength as a mediator of sex differences in incident knee osteoarthritis. Arthritis Res Ther. Published 24 January 2026. doi:10.
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