Relationship between medial meniscus extrusion and damage to medial stabilizers: Should extrusion be considered significant only when more than 3 mm?

BACKGROUND: This study was conducted with patients with anterior and medial extrusion of the medial meniscus (MM-AE, MM-ME) to investigate the relationship of the amount of extrusion with damage to the meniscus, meniscofemoral ligament (MFL), meniscotibial ligament (MTL), presence of effusion, osteoarthritis (OA) grade and other medial stablizers. A cut-off value for significant MM-ME was also suggested. METHODS: All patients aged 18 and above who had measurable MM extrusion on knee MRI were included. Patients with acute injury detected on knee MRI and any disease that could disrupt the anatomy were not included. The relationship between the amount of MM-AE, MM-ME and the investigated comorbidities were evaluated. The patients were divided into two: those with and without positive findings for each comorbidities. The amount of MM-AE, MM-ME were evaluated. ROC analysis was undertaken for significant differences, and cut-off values were determined. RESULTS: There was a correlation between MM-ME and age, weight, and BMI (p < 0.001, p = 0.027, p = 0.025, respectively). The amount of MM-ME was higher in the groups with OA (p = 0.007), MTL damage (p < 0.001), MFL damage (p < 0.001), meniscus damage (p < 0.001), effusion (p < 0.001), and the amount of MM-AE was higher in the groups with OA (p = 0.042), effusion (p = 0.002). The cut-off values of MM-ME were determined to be 2.69 mm (MTL), 2.65 mm (MFL), 2.49 mm (meniscus), and 2.85 mm (OA). CONCLUSION: OA grade, effusion, and meniscus, MTL, and MFL damage were all found to be related to the amount of MM-ME. MM-ME values 2.49-2.85 mm may indicate meniscus, MFL, MTL damage and OA.