Sonography in the diagnosis of tears of the knee menisci

PURPOSE: The aim of this study was to investigate the usefulness of sonography in diagnosing tears of the knee menisci. METHODS: In this retrospective study, we reviewed the sonographic examinations of the knees of 321 patients diagnosed with a torn meniscus on the basis of clinical findings. Of the 321 knees imaged, 216 were also examined using MRI or CT. Arthroscopic meniscectomy was performed on 126 knees. RESULTS: MRI or CT did not confirm 48% (71 cases) of the positive sonographic diagnoses (ie, false positives) and 72% (50 cases) of the negative sonographic diagnoses (ie, false negatives). Thus, the sonographic diagnosis was correct in 95 cases (44%) and incorrect in 121 cases (56%), yielding low rates of sensitivity (60%) and specificity (21%). Among the 126 cases in which arthroscopic meniscectomy was performed, arthroscopy confirmed 100% of the MRI or CT diagnoses of meniscal tears. CONCLUSIONS: Our results indicate that sonography is not accurate enough to be used as the only imaging modality for diagnosing tears of the knee menisci