Imaging of the Postoperative Meniscus.

In the postmeniscectomy or meniscal repair setting, there is overlap between expected postoperative change and findings of a re-torn meniscus, particularly increased T1-weighted or proton density signal contacting the articular surface. Protocol selection and accurate diagnosis requires knowledge of meniscal tear treatment, the expected postoperative appearance, and criteria for re-tear. Criteria for meniscal re-tear on MR imaging are high T2-weighted signal reaching the articular surface, abnormal meniscal morphology not explained by the surgery, or a displaced fragment. When MR arthrography is performed, a meniscal tear may or may not exhibit signal intensity as high as that of the intraarticular contrast.