Meniscal changes in the elderly: correlation of MR imaging and histologic findings.

In elderly patients, degenerative changes of the meniscus are common and may mimic a tear. The magnetic resonance (MR) image findings of 179 meniscal sections in 20 cadaver knees were correlated with the histologic and gross pathologic findings. The sensitivity of standard T1-weighted spin-echo images and their corresponding meniscal windows in depicting meniscal tears was 80.6%, specificity was 72.4%, and accuracy was 76.7%. These results are not as good as results reported previously. A major difficulty is the occurrence of grade 3 meniscal signal intensity and diffuse intrameniscal signal intensity in torn and intact menisci. MR imaging in elderly patients, however, is still useful in the diagnosis of meniscal abnormalities. Normal low signal intensity depicted within a meniscus at MR imaging and changes in grades 1 and 2 intrameniscal signal intensity are reliable signs of an intact meniscal surface. Grade 3 and diffuse meniscal signal intensities do not allow a specific diagnosis; menisci with these characteristics should be described as degenerated with a high probability of a tear.