Popliteal cysts and associated disorders of the knee. Critical review with MR imaging.

We have studied retrospectively the epidemiological features of popliteal cysts in adults and the incidence of associated intra-articular disorders in a series of 1001 patients undergoing magnetic resonance imaging who had been randomly referred to our institution. Images of popliteal cysts were seen in 4.7% of this group which is lower than in other studies with different imaging techniques. A communication with the joint was invariably found. The cysts were associated with one, or more, disorders detected by MRI in 94%. The commonest lesions were meniscal (83%), frequently involving the posterior horn of the medial meniscus, chondral (43%), and anterior cruciate ligament tears. Our data suggest that intra-articular disorders may play an important role in the pathogenesis of popliteal cysts in adults.