Magnetic resonance imaging of the postoperative knee.

Due to the recent development of arthroscopic techniques in meniscal surgery and anterior cruciate ligament reconstruction, an increasing number of postoperative patients are referred for a magnetic resonance examination of the knee because of recurrent injury. Contrary to the nonoperative patient, T2-weighted sequences and, in unequivocal cases, magnetic resonance arthrography play the most important role in the evaluation of a possible meniscal retear. In patients with anterior cruciate ligament reconstruction, the changes of the magnetic resonance appearance of the anterior cruciate ligament graft during the first year after surgery must be considered in the diagnosis of retears. Recent developments in articular cartilage defect repair and the possible role of magnetic resonance imaging in the follow-up are discussed.