MR imaging of the postoperative meniscus of the knee.

Surgery for tears of the menisci of the knee has evolved greatly over the last century and is now an extremely common procedure. Meniscal repair and conservative therapy are the preferred methods of treatment, but most symptomatic torn menisci do not meet the requirements for these options and necessitate partial meniscectomy. After surgery, patients often have recurrent pain and need additional diagnosis. Conventional magnetic resonance imaging (MRI) in the postoperative patient is very helpful at diagnosing extrameniscal pathology. It has lower sensitivity for detecting retears after partial meniscectomy, however, as it relies primarily on demonstration of fluid entering the meniscal retear on T2-weighted images. Similarly, conventional MRI is less accurate after meniscal repair, in which the repair site usually maintains altered signal for years. MR arthrography has higher sensitivity for detecting retears in menisci and is the procedure of choice in many situations.