Abnormal tibiofemoral kinematics following ACL reconstruction are associated with early cartilage matrix degeneration measured by MRI T1rho

Purpose: Altered kinematics following ACL-reconstruction may be a cause of post-traumatic osteoarthritis. T-1 rho MRI is a technique that detects early cartilage matrix degeneration. Our study aimed to evaluate kinematics following ACL-reconstruction, cartilage health (using T-1 rho MRI), and assess whether altered kinematics following ACL-reconstruction are associated with early cartilage degeneration. Methods: Eleven patients (average age: 33 +/- 9 years) underwent 3 T MRI 18 +/- 5 months following ACL-reconstruction. Images were obtained at extension and 30 degrees flexion under simulated loading (125 N). Tibial rotation (TR) and anterior tibial translation (ATT) between flexion and extension, and T-1 rho relaxation times of the knee cartilage were analyzed. Cartilage was divided into five compartments: medial and lateral femoral condyles (MFC/LFC), medial and lateral tibias (MT/LT), and patella. A sub-analysis of the femoral weight-bearing (wb) regions was also performed. Patients were categorized as having abnormal or restored ATT and TR, and T-1 rho, percentage increase was compared between these two groups of patients. Results: As a group, there were no significant differences between ACL-reconstructed and contralateral knee kinematics, however, there were individual variations. T-1 rho relaxation times of the MFC and MFC-wb region were elevated (p <= 0.05) in the ACL-reconstructed knees compared to the uninjured contralateral knees. There were increases (p <= 0.05) in the MFC-wb, MT, patella and overall average cartilage T-1 rho, values of the abnormal ATT group compared to restored ATT group. The percentage increase in the T-1 rho relaxation time in the MFC-wb cartilage approached significance (p = 0.08) in the abnormal versus restored TR patients. Conclusions: Abnormal kinematics following ACL-reconstruction appear to lead to cartilage degeneration, particularly in the medial compartment. (C) 2011 Elsevier B.V. All rights reserved.