Persistent magnetic resonance imaging-derived static anterior tibial translation after anterior cruciate ligament reconstruction is associated with elevated cartilage T2 relaxation times but not serum biomarkers

Persistent, static anterior tibial translation (sATT) alterations following anterior cruciate ligament reconstruction (ACLR) may influence cartilage health. T2 relaxation times and serum biomarkers of cartilage degradation/bone resorption provide insight into osteoarthritis development. The relationship between sATT and these markers is unknown. We aimed to determine if changes in sATT are associated with early signs of osteoarthritis development, preoperatively and 6 months post-ACLR. We conducted a secondary analysis of a prospective cohort study (Level 2) of 29 participants with ACL injury (N&#x2009;=&#x2009;29) through 6 months post-ACLR. Magnetic resonance imaging (MRI) was used to measure sATT in the medial and lateral tibiofemoral compartments and quantitative MRI was used to assess cartilage T2 relaxation times within 1 month of ACL injury (pre-ACLR) and 6 months post-ACLR. Serum biomarkers associated with cartilage and bone breakdown, including cartilage oligomeric matrix protein (COMP), matrix metalloproteinase-3 (MMP-3) and N-terminal telopeptide (NTX), were analyzed at pre-ACLR and 6 months. Pearson's correlations were used to determine associations between sATT with T2 relaxation time and serum biomarkers. sATT persisted in both medial and lateral compartments after ACLR and was significantly greater at 6 months on the injured knee compared to the uninjured knee (average difference of 1.6&#x2009;&#xb1;&#x2009;-2.1&#x2009;mm [p&#x2009;<&#x2009;0.001] and 1.5&#x2009;&#xb1;&#x2009;2.8&#x2009;mm [p&#x2009;=&#x2009;0.007] in the medial and lateral compartments, respectively). Greater interlimb difference in sATT at 6 months correlated with increased (worse) T2 relaxation times in the anterior lateral (r&#x2009;=&#x2009;0.386, p&#x2009;=&#x2009;0.038) and medial (r&#x2009;=&#x2009;0.426, p&#x2009;=&#x2009;0.021) femoral condyles. No significant associations were found between sATT and T2 relaxation times in other cartilage regions or with serum biomarker levels (p&#x2009;>&#x2009;0.05). sATT persisted after ACLR and greater persistence of sATT was linked to elevated T2 relaxation times in the anterior femoral condyles. These findings may provide further insight into a mechanism of cartilage deterioration after ACLR. Level II.