The Impact of Medial Meniscal Extrusion on Cartilage of the Medial Femorotibial Joint—A Retrospective Analysis Based on Quantitative T2 Mapping at 3.0T

<b>Background/Objectives</b>: The aim of this study was the investigation of any correlation between medial meniscal extrusion (MME) and T2 relaxation times. Furthermore, the impact of different meniscal morphologies on the femoral cartilage was assessed. <b>Methods</b>: Fifty-nine knees of fifty-five patients (twenty-four female, thirty-one male) with a mean age of 33.7 ± 9.2 years and without risk factors for MME or osteoarthritis were examined in a 3.0T MRI. MME was assessed quantitatively in accordance with BLOKS score. T2 maps were calculated from sagittal 2D MESE sequences. The region of interest was defined as the load-bearing cartilage at the medial femoral condyle and analysis was performed on two consecutive slices. T2 values were correlated to MME; furthermore, mean T2 values were compared in different grades of MME. <b>Results</b>: T2 values showed a strong correlation with increasing MME (r = 0.635; <i>p</i> < 0.001) in an exponential pattern. Analogously, knees with MME ≥ 3 mm showed statistically significant higher T2 values (<i>p</i> < 0.001) compared to knees with MME ≤ 2 mm and 2.1-2.9 mm; between the latter two, no differences in T2 values were found. <b>Conclusions</b>: T2 values showed a strong correlation with increasing MME. Consequently, MME ≥ 3 mm has a detectable impact on the cartilage of the femur.