Longitudinal changes in the total knee joint moment after anterior cruciate ligament reconstruction correlate with cartilage thickness changes.

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Abstract

This study investigated associations between changes in the total joint moment (TJM) at the knee and changes in cartilage thickness after anterior cruciate ligament reconstruction (ACLR). Seventeen subjects (5 males; age: 29.6±7.3yrs) with unilateral ACLR underwent gait analysis and MRI at baseline (2.2±0.3yrs post-ACLR) and at long-term follow-up (7.7±0.7yrs post-ACLR). Knee loading was assessed using the TJM, and differences in loading were analyzed using repeated measures ANOVA. Pearson correlation coefficients assessed associations between changes in TJM and changes in (medial-to-lateral) M/L femoral cartilage thickness ratios in the ACLR limb. Bilaterally there was no significant change in the magnitude of the TJM first peak (TJM1), however, there was a significant increase in percent contribution of the knee flexion moment (KFM) (p<0.001) and decrease in percent contribution of the knee adduction moment (KAM) to TJM1 (p<0.001). The change in percent contributions of KFM and KAM to TJM1 were associated with changes in M/L femoral cartilage thickness in the ACLR limb. Specifically, subjects with smaller increases in KFM contribution (R=0.521, p=0.032) and smaller decreases in KAM contribution (R=-0.521, p=0.032) had a reduction in M/L ratio in the central femoral sub-region over the follow-up period, with similar trends in the external femoral sub-region. The study results provide new insight into changes in the loading environment at the knee joint prospectively following ACL reconstruction and give evidence that there are modifiable gait metrics that are associated with cartilage changes after ACLR. This article is protected by copyright. All rights reserved.

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