Abstract
To assess the association between MRI findings and the clinical features of meniscal injuries, MRI finding were compared with surgical or arthroscopic findings in 53 middle-aged and elderly patients (13 men and 40 women with a mean age of 62.4 years) . The MRI sensitivity was a high of 94.3%, but specificity was only 71.7%, and accuracy was 83.0%. In many elderly patients, MRI signal intensity varied within the meniscus, suggesting a tear although none was present.
In order to identify the features reflected by MRI signal intensity changes, histopathological findings were compared with MRI findings in 22 menisci (11 medial and 11 lateral) from 13 patients with a mean age of 76.0 years. After MRI examination, the menisci were removed and sections were histologically examined. MRI signal intensity was rated on a scale of 0 to 4. Signal intensity was normal (Grade 0) in about 50% of the cases. Signal intensity over the anterior segments of the menisci was Grade 0 (normal) in 73.4%. Signal intensity over the posterior segments ranged from Grade 1 to 4 in 85.5%. When the signal intensity was Grade 0 or 1, there were no microscopic tears. However, the occurrence of microscopic tears and degeneration increased steadily at higher grades. In many elderly individuals, signal intensity varied within the meniscus due to degeneration of the cartilage, and in some cases meniscal injuries could not be distinguished from degeneration using MRI.
