Lower extremity muscle patterns and frontal plane biomechanics are altered in the contralateral knee of adults with osteoarthritis compared to asymptomatic adults.

PURPOSE: To compare knee joint muscle activity during gait between the contralateral limb of individuals with knee osteoarthritis (OA) and an asymptomatic older adult group. A secondary objective was to compare frontal and sagittal plane moment and sagittal plane motion features between groups.

SCOPE: 84 individuals with moderate knee OA (61 ± 6 years, 43 % female, BMI 29.2 ± 5.7 kg/m2 ), and 45 asymptomatic older adults (61 ± 7 years, 49 % female, BMI 25.0 ± 3.4 kg/m2 ) participated. Participants walked at a self-selected pace on a dual belt treadmill. Surface electromyograms of the quadriceps, hamstrings, and gastrocnemius, segment motions and ground reaction forces were recorded. Principal component analyses identified amplitude and temporal electromyogram features. Sagittal plane motion and net external sagittal and frontal plane moments were calculated. Analysis of Variance models using Bonferroni corrections determined between and within group differences in these gait features.

CONCLUSIONS: The contralateral knee showed prolonged lateral hamstring activation and altered temporal features of the gastrocnemius and greater knee adduction moments compared to asymptomatic adults. Group, muscle, or interaction effects were not found for the quadriceps. These findings highlight the importance of exploring the implications of contralateral knee function of individuals with moderate knee OA, particularly considering the altered antagonist muscle activations, and heightened frontal plane moments.