65-year-old male with pain and large effusion on radiographs. MENISCI: There is a complex tear of the medial meniscus with maceration of the posterior aspect of the body of the medial meniscus. There is branching signal abnormality which extends into the posterior horn, which is truncated, indicating additional complex tearing. There is a 1.0 cm focus of low signal intensity adjacent to the root of the posterior horn of the medial meniscus which likely represents a displaced meniscal fragment. The anterior horn of the medial meniscus appears intact. There is medial extrusion of the fragmented body of the medial meniscus. There is globular branching signal abnormality throughout the lateral meniscus, indicating intrasubstance degeneration. Within the anterior horn, the signal appears to extend to both the tibial and femoral articular surfaces, which may represent mild degenerative tearing or fraying, but we see no fluid signal intensity within the meniscus to confirm a large unstable tear.ARTICULAR CARTILAGE AND BONE: The superior aspect of the femoral trochlea appears shallow and there is prominence of the lateral facet relative to the medial facet, suggestive of femoral trochlear dysplasia. There is slight lateral translation of the patella relative to the center of the femoral trochlea. The tibial tubercle to trochlear groove distance is 1.5 cm, which is borderline normal. Moderate to severe degeneration affects the articular cartilage of the patella along its lateral facet, with small subchondral cyst formation. There is blistering of the articular cartilage of the medial facet of the patella with underlying subchondral cyst. Mild articular cartilage degeneration affects the femoral trochlea. There is moderate diffuse degeneration of the articular cartilage of the weightbearing portions of the medial femoral condyle and medial tibial plateau. The lateral compartment appears relatively preserved. There is osteophyte formation affecting the lateral compartment. Osteophytes are also noted in the medial compartment and patellofemoral compartment.LIGAMENTS: Cysts are noted in the intercondylar eminence. There is thickening and mild increased signal intensity of the ACL, suggesting mucoid degeneration with small cysts at its proximal attachment. The MCL appears intact, although intermediate signal intensity deep to the superficial band of the MCL likely represents synovitis. The PCL and LCL appear intact.EXTENSOR MECHANISM: The extensor mechanism appears intact. The Insall-Salvati ratio is 1.3, suggesting mild patella alta.ADDITIONAL
1. Extensive complex tearing of the medial meniscus.2. Osteoarthritis with findings suggestive of patellofemoral instability.3. Joint effusion, synovitis, and other findings as described above.