Meniscal knee injuries - Can magnetic resonance imaging (MRI) predict whether the knees can be repaired?

Menisci are pads of cartilage inside knee joints which ordinarily help protect against wear and tear on knee bones, but the menisci themselves are frequent sites of athletic injury. Fortunately, certain kinds of meniscal 'tears' can be repaired effectively by surgery, primarily when a tear is within the vascular zone of a meniscus, when the tear is rather long (greater than 10 mm), and when there is minimal damage to the torn meniscal segment and surrounding structures. If those conditions are not met, repair is often impossible, but how can one determine ahead of time if a repair procedure can really be undertaken?

(Preoperative knowledge helps surgeons plan procedures and obtain special equipment and assistants and also aids the patient in his/her decision about whether to go ahead with surgery) Since Magnetic Resonance Imaging (MRI) is an effective diagnostic tool in the evaluation of various knee disorders, it might help determine meniscal reparability.

To find out if this is the case, researchers at the Washington University School of Medicine in St. Louis, Missouri, recently examined 106 patients with meniscal tears using high-field-strength MRIs. Each scan was independently read by three examiners with various degrees of expertise (a musculoskeletal radiologist, a senior orthopaedic surgeon and a general radiologist). Each tear was described and categorised, and a prediction was made about whether the tear was reparable. As it turned out, there were 115 actual meniscal tears in the 106 patients, and the examiners' ability to correctly estimate tear type was fair to poor, with correct assessments in some cases being made only 14 per cent of the time. The researchers conclude that MRI is only moderately reliable for the prediction of meniscus reparability. Interestingly enough, the training of the MRI 'reader' does not seem to significantly influence the results.

'Magnetic Resonance Imaging as a Tool to Predict Meniscal Reparability,' The American Journal of Sports Medicine, vol. 27(4), pp. 436-443, 1999