Associations between habitual walking speed and in vivo tibial cartilage strain in individuals with anterior cruciate ligament reconstruction

The purpose of the study was to determine associations between habitual walking speed and an in vivo magnetic resonance imagining (MRI) measure of tibial cartilage strain following primary anterior cruciate ligament reconstruction (ACLR). Habitual walking speed was collected over ground in 12 individuals (5 Males/7 Females). Participants underwent an MRI of their ACLR knee to capture resting tibial articular cartilage thickness. Following the MRI, participants walked on a treadmill at their habitual walking speed for 3000 steps. Cartilage thickness was calculated for pre-loading and post-loading across the entire articulating surface and strain maps were created by calculating the change in thickness from pre- to post-loading thickness. Average cartilage strain was calculated in 6 evenly divided regions of interest (ROI) of the medial and lateral tibial cartilage. Spearman’s rank correlations and 95 % confidence intervals (CIs) (ρ) were used to assess associations between habitual walking speed and average tibial articular cartilage strain in each ROI. Slower habitual walking speed was moderately associated with greater strain in medial central inner tibial cartilage region (ρ=-0.67, 95 %CI=[-90,-0.14] ). All other associations between cartilage strain and medial (ρ range= -0.30 to 0.06, 95 %CI range=-0.75 to 0.62) or lateral (ρ range= -0.42 to 0.28, 95 %CI range=-0.81 to 0.74) tibial cartilage ROIs were weak to moderate. Our study demonstrates a measurable in vivo link between slower habitual walking speeds and greater cartilage strain, which provides further rationale for evaluating the mechanistic link between modifying habitual walking speed to influence important biophysical changes in cartilage health.