The association of the medial meniscus covering ratio with knee cartilage thickness at 15 medial compartment subregions as found by three-dimensional analysis using MRI

PurposeThe correlation of cartilage thickness measured by three-dimensional (3D) magnetic resonance imaging (MRI) and the medial meniscal coverage ratio (MMCR), which presented pathology of the medial meniscus extrusion (MME) in 3D MRI, has not yet been elucidated. The study's purpose was to retrospectively verify whether the average cartilage thickness calculated by the automatic MRI 3D analysis system for each subregion was correlated with MMCR.MethodsA total of 60 patients underwent medial meniscus repair or high tibial osteotomy to treat their medial knee osteoarthritis. Cartilage thickness and MMCR were automatically calculated using 3D MRI software. The MMCR was defined as the ratio of the area covered by the meniscus within the medial tibial cartilage area to the total medial tibial cartilage area. The association between MMCR and the average cartilage thickness at 15 subregions in the medial femoral condyle (MFC) and medial tibial plateau (MTP) was evaluated using Spearman's rank correlation coefficient.ResultsKellgren-Lawrence grade exhibited a negative correlation with MMCR and a positive correlation with MME width. Cartilage thickness in the MTP had a moderately positive correlation with MMCR at four subregions and a weakly positive correlation at another subregion. Cartilage thickness in the MFC showed a moderately positive correlation with MMCR at five subregions and a weakly positive correlation at one subregion.ConclusionsCartilage thickness calculated by automatic MRI 3D analysis system had a positive correlation with MMCR for all subregions of the anterior and middle subregions in the MFC and for five regions of nine subregions of the anterior and middle subregions in the MTP.Level of evidenceLevel II, cross-sectional study (diagnosis). Cartilage thickness calculated by automatic three-dimensional magnetic resonance imaging analysis system had a positive correlation with medial meniscus covering ratio for all subregions of the anterior and middle subregions in the medial femoral condyle and for five regions of nine subregions of the anterior and middle subregions in the medial tibial plateau. image