Evaluation Of Lateral Femoral Condylar Hypoplasia Using MRI In Patients With Discoid Lateral Meniscus

ObjectiveBy measuring some quantitative indexes of lateral femoral condyle between patients with discoid lateral meniscus and matched control in MRI, we aimed to evaluate the lateral femoral condylar hypoplasia of discoid lateral meniscus and found some excellent predictive parameters for diagnose discoid lateral meniscus.MethodsForty patients(20 male and 20 female)with discoid lateral meniscus and forty age-and sex-matched controls with normal meniscus, both arthroscopic diagnosis, were enrolled into two groups. Radius of distal lateral femoral condyle (Rd), angle of distal lateral femoral condyle (αd), radius of posterior lateral femoral condyle(Rp), angle of posterior lateral femoral condyle(a p), antero-posterior diameter of lateral femoral condyle (APDLFC), height of lateral femoral condyle(HLFC), surgical epicondylar axis(SECA), APDLFC/SECA, HLFC/SECA, posterior lateral condylar angle(PLCA), posterior medial condylar angle(PMCA), posterior condylar angle(PCA), PLCA/PMCA were measured in MRI.ResultsIn discoid lateral meniscus group, Rd, Rp, a d, HLFC, APDLFC/SECA, HLFC/SECA, PLCA and PLCA/PMCA were significantly smaller compared with the normal meniscus group(P<0.001). A significantly larger PCA was identified in discoid lateral meniscus group compared with the control group(P<0.001). APDLFC, a p, SECA, PMCA showed no significant difference in two groups. The cut-off values of PLCA/PMCA was 0.9266. With the cut-off value of diagnosing discoid lateral meniscus, the ROC curve area, sensitivity, specificity, positive predictive value, negative predictive value of PLCA/PMCA were 0.910, 92.5%,77.5%,80.4%,91.2%, respectively.ConclusionA shorter height of lateral femoral condyle, squaring of distal lateral femoral condyle, rounder and smaller posterior lateral femoral condyle, which means lateral femoral condylar hypoplasia, is typically seen in patients with discoid lateral meniscus. PLCA/PMCA can used as excellent predictive parameters for diagnosing discoid lateral meniscus.