THE ASSOCIATION OF THE MEDIAL MENISCUS COVERING RATIO WITH KNEE CARTILAGE THICKNESS AT THE MEDIAL FEMORAL CONDYLE AND TIBIAL PLATEAU EVALUATED BY 3D MRI ANALYSIS SOFTWARE

INTRODUCTION

Medial meniscus extrusion (MME) leads to reduced coverage of the tibial plateau, causing the development and progression of knee osteoarthritis (OA). The correlation of cartilage thickness measured by 3D MRI and the medial meniscal coverage ratio (MMCR), which presented pathology of the MME in 3D MRI, has not yet been elucidated.

OBJECTIVE

To retrospectively verify whether the average cartilage thickness calculated by the automatic MRI 3D analysis system for each subregion was correlated with MMCR.

METHODS

A total of 60 patients underwent medial meniscus repair or high tibial osteotomy to treat their medial knee OA. MRI was performed at 3.0 T (Achieva 3.0TX, Philips, Netherlands). Sagittal planes of the knee joints were acquired to obtain both fat-suppressed spoiled gradient echo sequence images and proton-weighted images. The MRI DICOM data were read by the SYNAPSE VINCENT 3D software (JSYNAPSE VINCENT, FUJIFILM Corp., Tokyo, Japan). Cartilage thickness and MMCR were automatically calculated using this 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 (Figure 1). 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.

RESULTS

KL 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.

CONCLUSION

Cartilage 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.