Medial meniscus extrusion is associated with acute cartilage deformation after mechanical loading during treadmill...

This study aimed to investigate whether the worsening of meniscus function caused by medial meniscus extrusion (MME) was associated with acute cartilage deformation in the medial femur after mechanical loading, which changes depending on the contact force on the cartilage.

This was a secondary analysis of our previous study investigating acute cartilage deformation after mechanical loading in older women. Fifty-six women, aged ≥50 years, participated in the previous study, 48 of whom (age: 70.3 ± 7.6 years) participated in the meniscus assessment and were included in this analysis. MME was assessed using ultrasonographic B-mode images acquired in the standing position. Acute cartilage deformation was assessed based on the reduction in cartilage thickness after 15 min of treadmill walking. The mechanical cumulative loading was calculated by multiplying the time integrals of the positive values of the knee adduction moment, as assessed by motion analysis with the number of steps taken during treadmill walking. Paired t-tests were performed to compare cartilage thickness in pre- and post-walking. In addition, multiple linear regression analysis was performed to investigate whether MME was associated with acute cartilage deformation after walking.

Significant cartilage deformation occurred after treadmill walking (pre-walking: 1.6 ± 0.3 mm, post-walking: 1.5 ± 0.3 mm, P < 0.001, effect size (r) = 0.760). MME was associated with the amount of acute cartilage deformation after walking, independent of cumulative mechanical loading or cartilage condition (unstandardized regression coefficient B = 0.013, 95% confidence interval: 0.001-0.025, P = 0.033, effect size (R²) = 0.144).

Greater MME is associated with increased acute cartilage deformation after mechanical loading.