Worse Tibiofemoral Cartilage Composition is Associated with Insufficient Gait Kinetics Following ACL Reconstruction

Greater articular cartilage T1ρ magnetic resonance imaging relaxation times indicate less proteoglycan density and are linked to posttraumatic osteoarthritis development following anterior cruciate ligament reconstruction (ACLR). While changes in T1ρ relaxation times are associated with gait biomechanics, it is unclear if excessive or insufficient knee joint loading is linked to greater T1ρ relaxation times 12 months post-ACLR. The purpose of this study was to compare external knee adduction (KAM) and flexion (KFM) moments in individuals after ACLR with high vs. low tibiofemoral T1ρ relaxation profiles and uninjured controls. Gait biomechanics were collected in 26 uninjured controls (50% females, age 22 ± 4 yrs., BMI 23.9 ± 2.8 kg/m2) and 26 individuals after ACLR (50% females, age 22 ± 4 yrs., BMI 24.2 ± 3.5 kg/m2) at 6 and 12 months post-ACLR. ACLR-T1ρHigh (n = 9) and ACLR-T1ρLow (n = 17) groups were created based on 12-month post-ACLR T1ρ relaxation times using a k-means cluster analysis. Functional analyses of variance were used to compare KAM and KFM. ACLR-T1ρHigh exhibited lesser KAM than ACLR-T1ρLow and Uninjured Controls 6 months post-ACLR. ACLR-T1ρLow exhibited greater KAM than Uninjured Controls 6 and 12 months post-ACLR. KAM increased in ACLR-T1ρHigh and decreased in ACLR-T1ρLow between 6-12 months, both groups becoming more similar to Uninjured Controls. There were scant differences in KFM between ACLR-T1ρHigh and ACLR-T1ρLow 6 or 12 months post-ACLR, but both groups demonstrated lesser KFM compared to Uninjured Controls. Associations between worse T1ρ profiles and increases in KAM may be driven by the normalization of KAM in individuals who initially exhibit insufficient KAM 6-months post-ACLR.