Does long‐term lower extremity strength training in adults with knee osteoarthritis and varus alignment reduce knee joint loading during gait?

Objective We examined whether 18 months of strength training in individuals with knee varus alignment and medial tibiofemoral osteoarthritis (OA) reduced knee joint loads during walking compared to an attention control group. Methods This study was a secondary analysis of a randomized clinical trial that compared the effects of strength training to a control group in adults with knee OA. For this analysis, control participants had knee varus malalignment (≥2 degrees varus) (N=49); participants in the strength training group met the varus malalignment criterion and increased their hip abductor strength by ≥20% from baseline to 18‐month follow‐up (N=39). Linear regressions were used to compare means between groups at 18 months. Results The strength training group had greater increases in strength in the quadriceps (45%), hamstrings (68%), and hip abductors (42%) than the control group (16%, 11%, 4%)(P< 0.05). There were no significant differences in the mean peak internal knee abduction moment or mean peak knee compressive force between groups at 18‐month follow‐up. The adjusted means at 18‐month follow‐up for the internal knee extension moment were significantly less (27%) in the strength training group (P adjusted = 0.03). Conclusion Among older adults with knee osteoarthritis and varus alignment, long‐term lower extremity strength training results in significant increases in strength but does not significantly alter most measures of knee joint loading during walking relative to an attention control group. The results cast doubt on whether clinically meaningful improvement in lower extremity muscle strength translates to clinically important attenuation in knee joint loading.