Abstract: Objective: This study aimed to screen the risk factors of medial meniscus extrusion, and to construct a logistic regression model based on radiography and magnetic resonance imaging (MRI). Methods: From August 2020 to June 2023, a total of 156 patients were diagnosed with medial meniscus injury. Medial meniscus extrusion of ≥3 mm on coronal MRI of non-weight bearing knee joints was used as a diagnostic criterion. The patients were divided into two groups: the extrusion group (71 cases) and non-extrusion group (85 cases). Results: A univariate analysis revealed that the extrusion group had higher values for age, female proportion, meniscus tears at various locations (anterior horn/body/root), knee Kellgren-Lawrence (K-L) grade ≥Ⅲ, cartilage injury Recht grade > Ⅲ, and presence of genu varum. Multivariate logistic regression showed that based on radiography indicators, the knee K-L grade ≥Ⅲ (OR = 0.051) and presence of genu varum (OR = 0.152) were independent risk factors for extrusion. The area under the ROC curve of medial meniscus extrusion was 0.902, with a sensitivity of 80.0% and specificity of 100%. After combining MRI indicators, medial meniscus root tear (OR = 0.053), knee K-L grade ≥Ⅲ (OR = 0.160), cartilage injury Recht grade > Ⅲ (OR = 0.184), and presence of genu varum (OR = 0.177) were independent risk factors for extrusion. The area under the ROC curve of medial meniscus extrusion was 0.975, with a sensitivity of 100% and specificity of 87.5%. Conclusion: The medial meniscus root tear, knee K-L grade ≥Ⅲ, cartilage injury Recht grade > Ⅲ, and presence of genu varum were the primary risk factors of medial meniscus extrusion. The radiography model can serve as a clinical screening tool, while the model combining MRI offers more accurate assessment of individual risk, supporting the development of personalized intervention strategies (such as meniscus repair combined force line correction).