Relationship Between Early Cartilage Degeneration With T1ρ and T2 Analysis in Medial Tibial Cartilage and 10-Year Posttraumatic Osteoarthritis Progression After ACL Reconstruction

Background: Quantitative magnetic resonance imaging (qMRI), such as T1ρ and T2 mapping, allows for the characterization of the biochemical composition of cartilage and the detection of early degeneration within 1 year after anterior cruciate ligament reconstruction (ACLR). It remains unclear if early imaging biomarkers are associated with the long-term development of posttraumatic osteoarthritis (PTOA). Hypothesis/Purpose: The study aimed to investigate the relationship between qMRI-based evaluation of the medial compartment at baseline and 1 year after ACLR and the knee joint morphological status using 3-dimensional (3D) MRI at a 10-year follow-up. It was hypothesized that elevated T1p and T2 values at 1 year after ACLR would correlate with increased degenerative joint disease at 10 years after ACLR. Study Design: Cohort study; Level of evidence, 3. Methods: Patients with ACLR between 2011 and 2014 who had preoperative bilateral qMRI were included. Thirteen patients completed the 10-year follow-up and were evaluated. The mean T1ρ and T2 values at baseline and 1 year were obtained using in-house–developed software with MATLAB. The MRI scans at the 10-year follow-up were acquired using a 3-T MRI scanner, including bilateral 3D proton-density fat-saturated fast-spin-echo sequence. Two radiologists used the modified Whole-Organ Magnetic Resonance Imaging Score (WORMS) to grade the images. The correlations between baseline, 1-year, and delta (1 year – baseline) T1ρ/T2 values and the WORMS at 10 years postoperatively were analyzed using the Spearman correlation coefficient. Significance was defined as a P value <.05. Results: The baseline, 1-year, and delta medial tibia (MT) T1ρ values were significantly associated with the 10-year WORMS Total Score ( r = 0.604, P = .031; r = 0.604, P = .031; and r = 0.582, P = .039, respectively). The MT T2 value at 1 year postoperatively was significantly associated ( r = 0.566; P = .046) with the 10-year WORMS Total Score. Conclusion: The T1ρ/T2 values 1 year postoperatively and the increase from baseline to 1 year in the MT cartilage after ACLR were associated with the deterioration of the comprehensive evaluation of the knee at 10 years postoperatively. These findings help establish qMRI as a valuable biomarker for detecting early signs of PTOA progression.