Comparison of T1rho relaxation times between ACL-reconstructed knees and contralateral uninjured knees

The goal of this study is to compare the cartilage of anterior cruciate ligament (ACL)-reconstructed and uninjured contralateral knees using T (1 rho) MRI 12-16 months after ACL reconstructions. Eighteen patients with ACL-reconstructed knees (10 women, 8 men, mean age = 38.3 +/- A 7.8 years) were studied using 3T MRI. Injured and contralateral knee MR studies were acquired 12-16 months post-operatively. Cartilage sub-compartment T (1 rho) values of each injured knee were compared with the contralateral knee's values. Subgroup analysis of sub-compartment T (1 rho) values in both knees was performed between patients with and without meniscal tears at the time of ACL reconstruction using a paired Student's t test. In ACL-injured knees, the T (1 rho) values of the medial tibia (MT) and medial femoral condyle (MFC) were significantly elevated at 12-16 months follow-up compared to contralateral knees. Patients with a medial meniscal tear had higher MFC and MT T (1 rho) values compared to respective regions in contralateral knees. Patients with lateral meniscal tears had higher lateral femoral condyle and LT T (1 rho) values compared to respective regions in contralateral knees. There were no differences between the injured and contralateral knees of patients without meniscal tears. T (1 rho) MRI can detect significant changes in the medial compartments' cartilage matrix of ACL-reconstructed knees at 1 year post-operatively compared to contralateral knees. The presence of a meniscal tear at the time of ACL reconstruction is a risk factor for cartilage matrix degeneration in the femorotibial compartments on the same side as the meniscal tear.