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.