The Impact of Posterior Root Tears of the Medial Meniscus on Meniscal Extrusion and Cartilage Degeneration

Background : To explore the impact of the severity of the tear gap caused by medial meniscus posterior root (MMPR) tear on medial meniscus extrusion and bone cartilage based on magnetic resonance imaging (MRI). Methods : A retrospective analysis was conducted on 153 patients with medial meniscus root tear who were admitted to Jinhua Central Hospital from January 1, 2020, to October 31, 2023. According to the size of the tear gap, they were divided into mild displacement (M) group (≤4mm) and extensive displacement (W) group (>4mm). The M group consisted of 73 cases (70 females, 3 males), aged 52-63 years (mean age 56 years); the W group consisted of 80 cases (75 females, 5 males), aged 55-65 years (mean age 57.5 years). There was no significant difference in age and gender between the two groups (P>0.05). The distances of medial meniscus extrusion and bone cartilage injury in the two groups were compared and analyzed. Results : In the M group, the average extrusion distance of the medial meniscus was 3.5mm (1.5-5mm), and in the W group, the average extrusion distance of the medial meniscus was 4.53mm (2.5-7.3mm). The comparison between the two groups was statistically significant (P<0.05). The degree of femoral medial condyle cartilage degeneration was more severe in the W group, which was statistically significant compared with the M group (P<0.05). In the W group, bone hyperplasia, subchondral cyst formation, and narrowing of the medial compartment were more common, but there was no significant difference compared to the M group (P>0.05). Conclusion : The size of the tear gap caused by medial meniscus root tear on MRI is an important risk factor for medial meniscus extrusion and bone cartilage degeneration, which can provide a good idea for predicting the progression of osteoarthritis clinically.