Interlimb differences in T1ρ MRI relaxation times linked with symptomatic knee osteoarthritis following anterior cruciate ligament reconstruction.

Abstract

Lower proteoglycan density, as estimated by greater T1ρ magnetic resonance imaging (MRI) relaxation times, may be an indicator of early osteoarthritis development. We examined associations between femoral cartilage inter-limb T1ρ MRI relaxation time ratios and clinically relevant knee symptoms at 12 months following anterior crucial ligament reconstruction (ACLR). Twenty-nine individuals completed the Knee Osteoarthritis Outcome Score (KOOS) and underwent MRI 12 months following ACLR for this cross-sectional study. Participants were categorized as symptomatic or asymptomatic for clinically relevant knee symptoms consistent with osteoarthritis based on a standard KOOS classification. T1ρ MRI relaxation times were segmented in the weightbearing regions of lateral and medial femoral condyle (LFC and MFC). Inter-limb T1ρ MRI relaxation time ratios were calculated by normalizing the ACLR to the uninjured knee. T-tests were used to compare LFC and MFC interlimb T1ρ relaxation time ratios between individuals with and without knee symptoms. A Receiver Operating Characteristic (ROC) Curve analysis was used to determine a critical inter-limb T1ρ relaxation time ratio identifying symptomatic patients. Odds ratios (OR) and 95% confidence intervals (CI) estimated the association between the critical value and clinically relevant knee symptoms. Symptomatic individuals had significantly higher LFC inter-limb T1ρ MRI relaxation time ratios compared to asymptomatic individuals (p = 0.04). Individuals with an LFC inter-limb T1ρ MRI relaxation time ratio >1.11 were more likely to have symptoms (OR 8.5; 95%CI = 1.25-57.93). Individuals with greater inter-limb LFC T1ρ MRI relaxation time ratios 12 months post-ACLR may be more likely to exhibit symptoms consistent with knee OA.