Quadriceps strength is not related to gait impact loading in knee osteoarthritis

Joint loading has been implicated in the pathogenesis of knee osteoarthritis (OA). While compartment-specific measures such as the knee adduction moment have received much attention in the literature, less is known about other measures of dynamic loading in this patient population. This cross-sectional study assessed strength and walking patterns of 204 individuals with radiographically confirmed medial tibiofemoral OA and varus malalignment. Pearson product moment correlations and regression analyses were used to determine the bivariate and multivariate relationships amongst measures of impact loading (rate of loading and heelstrike transient occurrence) with demographic, clinical (in particular, radiographic disease severity, lower limb alignment, and self-reported pain and function), and biomechanical variables (maximum voluntary isometric quadriceps strength and gait kinematics). While maximum voluntary isometric quadriceps strength was significantly correlated with rate of loading (r>0.27) when walking at a freely chosen speed, multiple regression analyses indicated that rate of loading was primarily dictated by walking speed (p<0.001), and the effect of quadriceps strength was insignificant when accounting for all other included variables. Individuals who exhibited a heelstrike transient in their vertical ground reaction force profile were significantly more varus malaligned and were more likely to demonstrate severe radiographic degeneration than those who did not exhibit heelstrike transients. These results demonstrate higher impact loading during walking in those with knee OA with faster self-selected walking speeds, though the relationship with quadriceps strength is less clear. Importantly a potential association between disease characteristics, such as malalignment and disease severity, and higher impact loading was also observed.