Accuracy of MRI in meniscal tears

In order to assure diagnostic accuracy, 172 knee joints were examined prosp ectively by MRI. After MRI, all knee joints were examined by arthroscopy. T ears of the medial meniscus were found in 102 patients,the lateral meniscus showed a tear in 29 cases. Assuming that arthroscopy represents the golden standard of diagnostic measure concerning the knee joint, it can be stated that false-positive MRI findings on the medial and lateral meniscus were d iagnosed in three cases and false-negative MRI findings were diagnosed for two knee joints regarding the medial meniscus and four times regarding the lateral meniscus. For the medial meniscus a sensitivity of 98%,a specificit y of 96%,an accuracy of 94%, and the positive and negative value of predict ion were calculated at 97% each. Regarding the lateral meniscus, a sensitiv ity of 85%, a specificity of 98%, an accuracy of 92%, a positive predictive value of 88%, and a negative predictive value of 85% were found. Under the prerequisite that the MRI is carried out correctly and assessed by an expe rienced radiologist,the accuracy of the MRI for meniscus diagnosis is almos t equivalent to the one by arthroscopy. Under these conditions, MRI can be recommended when no safe and sufficient clinical diagnosis can be made. The rate of unnecessary arthroscopies with a pure diagnostic purpose can be lo wered significantly by means of MRI.