Objective To investigate the predictive value of combining MRI with full-length X-ray of both lower extremities in grading varus knee osteoarthritis(KOA).Methods A retrospective analysis was conducted on 176 patients diagnosed with varus KOA.All patients underwent X-ray K-L grading.Correlation analysis was performed between K-L grading and variables such as gen-der,age,side,meniscus grading,hip knee ankle(HKA)angle,meniscus peripheral displacement,medial osteochondral injury grad-ing,and medial bone marrow edema(BME)score.Varus KOA was converted into a binary classification variable of mild and severe osteoarthritis.Statistically significant variables were introduced into univariate and multivariate logistic regression models for analysis to screen out predictive factors for varus KOA grading.Diagnostic efficacy evaluation of predictive factors was further conducted using receiver operating characteristic(ROC)curves and other statistical methods.Results K-L grading was correlated with age,HKA angle,meniscus grading,meniscus peripheral displacement,medial osteochondral injury grading,and medial BME score,with r of 0.344,-0.584,0.369,0.443,0.586,and 0.616,respectively.Through univariate and multivariate logistic regression models,three predictive factors were finally selected:meniscus peripheral displacement,medial BME score,and HKA angle,with odds ratio(OR)values of 1.374,1.258,and 0.772,respectively.The area under the curve(AUC)of ROC curves were 0.736,0.804,and 0.799,with 95％confidence interval(CI)of 0.662-0.810,0.740-0.867,and 0.731-0.868,respectively.At cut-off values of 3.5 mm,5.5 and 174.5°,the sensitivity were 64.0％,62.3％,and 80.7％,the specificity were 80.6％,83.9％,and 66.1％,and the accuracy were 70.0％,70.0％,and 75.6％,respectively.Conclusion The three imaging indications of medial BME score,HKA angle,and meniscus periph-eral displacement can provide preliminary predictions for mild and severe grading of varus KO A,offering valuable references for clini-cal treatment selection.