70-year-old man with left knee pain. MENISCI: There is severe mucoid degeneration of the posterior horn of the medial meniscus with intrameniscal cyst formation and extensive degenerative tearing of the posterior horn. Intrasubstance degeneration extends into the body of the medial meniscus, with signal contacting the undersurface of the meniscus, likely representing additional degenerative tearing. The anterior horn of the medial meniscus appears preserved. The lateral meniscus has minimal intrasubstance degeneration, but otherwise appears normal for age.ARTICULAR CARTILAGE AND BONE: There is full-thickness degeneration and fissuring of the articular cartilage of the lateral facet of the patella with underlying subchondral cyst formation. There is relatively mild degeneration of the articular cartilage of the medial facet of the patella. Relatively mild degeneration also affects the femoral trochlea. There is full-thickness degeneration of the articular cartilage along the weightbearing portion of the medial tibial plateau and along the medial femoral condyle above the degenerated posterior horn of the medial meniscus. There are underlying subchondral cysts in this region of the medial femoral condyle. There is also full-thickness fissuring of the articular cartilage of the lateral femoral condyle above the posterior horn of the lateral meniscus. There is a rounded focus of signal abnormality in the proximal tibia near the attachment of the PCL, which may represent an intraosseous ganglion.LIGAMENTS: The cruciate and collateral ligaments are intact. EXTENSOR MECHANISM: The extensor mechanism is intact.ADDITIONAL
1. Tricompartmental osteoarthritis as described above.2. Severe mucoid degeneration of the medial meniscus with degenerative tearing as described above.3. Joint effusion and other findings as above.