Osteonecrosis of the knee MENISCI: There is linear increased signal within the posterior horn of the medial meniscus with extension to the tibial articular surface indicating a horizontal tear. There is globular and linear increased signal throughout the lateral meniscus indicating intrasubstance degeneration but no tear is identified.ARTICULAR CARTILAGE AND BONE: There is fragmentation of the weightbearing articular surface of the medial femoral condyle indicating osteonecrosis with separation of the articular cartilage and subchondral bone plate from the underlying condyle over an AP diameter of nearly 4 cm. There is subchondral cyst formation and edema in the underlying marrow. The articular cartilage of the lateral compartment is intact. There is a small focal full-thickness defect within the articular cartilage of the medial patellar facet with underlying subchondral bone marrow change. Subjectively, there is mild diffuse thinning of the medial patellar cartilage and the articular cartilage of the femoral trochlea is intact.LIGAMENTS: Subjectively, there is thickening of the superficial band of the medial collateral ligament which may be related to prior sprain. The remaining cruciate and collateral ligaments are intact.EXTENSOR MECHANISM: There is bandlike low signal intensity anterior to the patella and distal to the quadriceps tendon which may reflect chronic scarring. Otherwise the extensor mechanism is intact.ADDITIONAL
1. Advanced subchondral osteonecrosis of the medial femoral condyle with articular fragmentation and subchondral cystic changes.2. Horizontal tear of the posterior horn of the medial meniscus.3. Large Baker's cyst with additional findings described above.