Purpose

Feasibility study using innovative MRI sequences to classify zonal and compositional changes within the ACL and PCL.

MRI has been used as a quantitative tool to evaluate tissue composition within cartilage in arthritic and non arthritic knees. These advanced techniques have rarely been used on other tissues within the knee joint. Compositional changes may represent early disease before macroscopic or structural changes become apparent, and act as a non invasive biomarker.

This study is the first to investigate MRI biomarkers (T1rho and T2) of the anterior (ACL) and posterior (PCL) cruciate ligaments in MSK disease and control patients. It was hypothesized that there would be variation in the biomarker values between 3 sub-regions (proximal, middle and distal thirds) and that there would be differences in this variation between the two groups.

Methods and Materials

15 patients with mild-to-moderate osteoarthritis (OA) Kellgren-Lawrence 2 and 3 and 5 controls were imaged using a 3.0-T MRI system. The ligaments were segmented manually at two time points to assess intra-rater reliability. Median T1rho and T2 values were recorded.

Results

In the OA group, it was found that the T1rho and T2 values for the distal ACL varied significantly from the middle and proximal parts. In the control group, the distal PCL T2 parameter varied significantly from the rest of the ligament (all p<0.02). Additionally, a significant difference between the OA and control groups was found in the variation of the T2 values across the PCL (P<0.03). High intra-rater reliability was found.

Conclusion

This study validates the technique of segmenting the cruciate ligaments, producing 3D structural models and assessing compositional changes. This may have potential clinical utility in new techniques of biological augmentation of in ACL injuries and in the assessment of ACL primary and augmented repair.