Diagnostic accuracy of magnetic resonance imaging for meniscal tears in dogs affected with naturally occuring cranial cruciate ligament rupture

A stifle magnetic resonance (MR) imaging protocol was developed based on the appearance of the cruciate ligaments and menisci in normal dogs. Proton density images were subjectively considered to have the highest likelihood of detecting a meniscal lesion. Following this initial evaluation, the accuracy of high-field MR imaging to detect meniscal tears in dogs was evaluated in 11 dogs suffering from naturally occurring cranial cruciate ligament rupture. Dogs underwent MR imaging of the affected stifle before surgery. MR imaging and surgical findings were assessed independently, and then compared. Five tears of the medial meniscus were correctly diagnosed with MR imaging and 19 normal menisci were accurately characterized as such, based on MR images. In one medial meniscus, changes consistent with meniscal degeneration were seen on MR images but this was not seen at surgery. With regard to the lateral meniscus, one false positive diagnosis of a tear was made and this likely represented a normal variation. One other lateral meniscus had changes consistent with meniscal degeneration but, as with the similar lesion seen in the medial meniscus, this was not confirmed surgically. The global sensitivity of MR imaging for the diagnosis of a meniscal tear was 100% and the specificity was 94%. High-field MR imaging is a reliable method to diagnose meniscal tears preoperatively and this may be useful in selecting the surgical approach to clinically abnormal joints and may decrease the need for arthrotomy.