There have been multiple recent refinements in the arthroscopic techniques of meniscal surgery and anterior cruciate ligament (ACL) reconstruction, and these are now allowing many postoperative patients to resume an active lifestyle. A result is an increasing number of postoperative patients who are referred for a magnetic resonance (MR) scan of the knee because of a recurrent injury. In this article, we will discuss some of the MR findings of retorn menisci and the role of MR arthrography. We will also review the changes that occur in the MR appearance of the ACL graft during the first year after surgery, and its effect on the accuracy of diagnosing graft tears. The MR findings after other less common knee procedures will also be described.