What does this research mean for the field?

Lower limb strength deficits and inter-limb asymmetry significantly contribute to postural instability in older adults with moderate knee osteoarthritis, and these deficits can be effectively evaluated using clinically feasible tools such as handheld dynamometry and posturography. Novelty: ClaimNovelty.INCREMENTAL. Consensus alignment: ConsensusAlignment.NEUTRAL.

What question did this study set out to answer?

This study aims to assess lower-limb strength and postural sway in adults with knee osteoarthritis compared to healthy controls.

June 1, 2026Open Access

Clinically feasible biomechanical assessment of lower limb strength and postural stability in adults aged 50–75 years with moderate knee osteoarthritis: implications for technology-enabled healthy aging

Key Points

This study aims to assess lower-limb strength and postural sway in adults with knee osteoarthritis compared to healthy controls.
Cross-sectional analysis of 90 participants (45 with KOA, 45 controls) aged 50–75 years.
Strength assessed using handheld dynamometry; postural sway measured via static posturography.
Correlations and associations evaluated using Pearson correlation and multiple linear regression analyses.
KOA participants had significantly greater sway area and velocity, reduced stance time, and lower strength compared to controls (p < 0.001).
Quadriceps strength (β = −0.024, p < 0.001) and limb symmetry index (β = −0.062, p = 0.001) predicted sway area under eyes-closed conditions.
LSI and quadriceps strength correlated strongly with sway parameters and stance performance.

Abstract

Objectives This study aimed to compare lower-limb muscle strength and postural sway between individuals with KOA and healthy controls, and to examine the association between strength parameters and postural stability using clinically feasible assessment methods. Methods A cross-sectional analysis was conducted among 90 participants (45 KOA, 45 matched controls). The participants were older adults aged 50–75 years, and 40.0% of the KOA group and 42.22% of the control group were male. Participants with knee osteoarthritis were classified as having moderate disease severity based on Kellgren–Lawrence grades II–III. Strength and balance assessments were conducted in a counterbalanced order, with a standardized 10-min rest interval between testing sessions to minimize fatigue effects. Isometric quadriceps and hamstring strength were measured using handheld dynamometry. Postural sway metrics—sway area, sway velocity, and single-leg stance time—were assessed via static posturography. Limb symmetry index (LSI) and quadriceps-to-hamstrings (Q: H) ratio were calculated. Pearson correlation and multiple linear regression analyses examined associations between strength and postural control. Results KOA participants showed significantly greater sway area and velocity, reduced stance time, and lower quadriceps and hamstrings strength compared to controls (all p 0.001). Quadriceps strength (β = −0.024, p 0.001) and LSI (β = −0.062, p = 0.001) were independent predictors of sway area under eyes-closed conditions. LSI and quadriceps strength were strongly correlated with sway parameters and stance performance. Conclusion Lower limb strength deficits and inter-limb asymmetry significantly contribute to postural instability in individuals with KOA. Objective, clinically feasible tools such as handheld dynamometry and posturography can support evaluation and inform rehabilitation strategies targeting strength and balance.

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