From paradox to population impact: Rethinking strengthening in knee osteoarthritis - A state-of-the-art review

To examine why quadriceps strengthening, although guideline-endorsed and biologically plausible, often delivers only modest and inconsistent population-level benefits in knee osteoarthritis (KOA).

We performed a state-of-the-art narrative review of clinical trials, meta-analyses, guidelines, and implementation-oriented literature on strengthening for KOA, with emphasis on efficacy, real-world effectiveness, adherence, heterogeneity, and delivery context.

Strengthening remains one of the best-supported non-pharmacological interventions for KOA and provides average improvements in pain and function. However, these benefits are often attenuated in routine care. Key modifiers include patient heterogeneity, fluctuating symptom burden, multimorbidity, adherence decay after supervision ends, under-dosing, and structural barriers such as limited follow-up support and reimbursement. Current evidence supports individualized adaptation of strengthening within a common high-quality framework rather than a one-size-fits-all prescription. Future trials should address heterogeneity of treatment effect prospectively and incorporate implementation outcomes such as adherence, fidelity, and sustainability.

The main challenge in KOA strengthening is no longer whether it can work, but under what conditions it can work consistently at scale. Better outcomes are likely to depend on individualized progression, skilled interventionists, flare-aware delivery, and health-system structures that support long-term therapeutic dosing.