The association between habitual walking speed and medial femoral cartilage deformation following 30minutes of walking.

Habitual walking speed is a key functional outcome that has implications for knee biomechanics that occur during gait. Lower extremity biomechanics during walking affects the loading of the femoral cartilage. Ultrasonography (US) can be used to assess resting femoral cartilage thickness and acute cartilage deformation in response to walking. The purpose of this study was to determine the association between habitual walking speed and both resting femoral cartilage thickness and deformation. Twenty-four healthy participants with no history of knee injury volunteered for this study. Habitual walking speed was assessed with a 20-m walk test. Femoral cartilage thickness was assessed with US in the medial condyle, lateral condyle, and intercondylar regions prior to and immediately following 30min of walking. Femoral cartilage deformation was calculated as the percent change in cartilage thickness acutely following the walking protocol. Separate Pearson product moment correlations were used to assess the association between habitual walking speed and each US cartilage variable. Slower habitual walking speed was significantly associated with greater medial femoral cartilage deformation (r=0.48, P=0.018), but not with lateral and intercondylar deformation. Habitual walking speed was not significantly associated with the resting cartilage thickness in any cartilage region. These findings highlight the in vivo association between walking speed and medial femoral cartilage deformation. When controlling for body mass index, the association between walking speed and medial cartilage deformation was weakened (Δr=-0.12). Future studies are needed to determine the extent to which BMI influences the association between walking speed and cartilage deformation.