The authors present six cases of cysts of the semilunar cartilages of the knee detected by ultrasonography, all of them confirmed at the time of surgery. Five of these lesions were cysts of the lateral meniscus; one lesion was a cyst of the medial meniscus. Because of ultrasonogra· phy, an accurate diagnosis of meniscal cysts is within the reach of the radiologist; it is also possible to visualize the extension of these lesions in a correct way, thereby being of great help to orthopedic surgeons. The main advan-C ysts of the semilunar cartilages of the knee have been recognized as a clinical entity since the beginning of this century.u Since then there have been many papers on this subject, almost all of them written by orthopedic surgeons. In fact the radiologist has been of little help in the diagnosis of meniscal cysts. Conventional radiography of the knee gave no · satisfactory information about these lesions. 3 Arthrography of the knee had been proven to be of very limited value in the diagnosis of cysts, mainly because of the fact that if the cysts were large enough to be shown radiologically, most of them were also large enough to be diag· nosed clinically. Arthrography can be used to confirm the clinical diagnosis or to determine differential diagtages of this technique compared with magnetic resonance imaging (MRI), which is also able to give the same information, are the short time required to perform the examination and the low costs. After outlining their study, the authors give a review of the literature concerning the incidence, clinical features, pathogenesis, and management of the disease. KEY WORDS: semilunar cartilage; meniscus; meniscal cysts, ultrasound studies. (/ Ultrasound Med 9:333, 1990) nosis, but its main interest lies in confirming the pres· ence or absence of tears preoperatively."Thanks to the enormous progress in recent radiologic techniques, namely ultrasonography and magnetic resonance imaging (MRI), we now are able to make a correct evaluation of these cystic lesions even when they are small and when the tears are microscopic, preventing the filling of the cysts by intra-articular contrast medium.
METHODS AND PATIENTSAll patients were studied with a 7.5-MHz probe on a Toshiba 90 SSA or 100 SSA. Longitudinal slices of the knee joint were obtained in lateral decubitus, procubitus, or dorsal decubitus, depending on the location of Received July 7, 1989, from the •Department of Radiology. Hopital the swelling. Attention was paid to the meniscus, usingMoliere-Longchamp Brussels, Belgium; and the 1{>epartment of Radi~ the method described by Sohn et al. 5 The relationship ology. Bordet Institute, Brussels, Belgium. Revised manuscript ac~ between the cystic mass and the meniscus was very cepted for publication December 7, 1989. carefully studied.