The meniscal "pseudocyst." A clinical sign of a torn meniscus.

We report a study of 636 patients requiring knee surgery, all of whom underwent detailed preoperative assessment. Fifty-eight patients had a clinical sign of a lump on the joint line when the knee was examined at 45 degrees of flexion, which has been thought to indicate a meniscal cyst. Of these 58 patients, however, only 30 patients had a meniscal cyst demonstrated at surgery. The remaining 28 patients had a meniscal tear without a cyst. In these 28 cases, the clinical sign of a lump protruding from the joint line was termed a "pseudocyst." This new clinical sign is important because of its frequency of occurrence and the complete correlation with meniscal tears requiring surgical intervention.