27-year-old female with knee pain. Evaluate for knee avascular necrosis. MENISCI: The medial and lateral menisci appear intact.ARTICULAR CARTILAGE AND BONE: There is poorly defined intermediate to low signal intensity within the subchondral marrow of the distal femoral epiphysis, likely corresponding to the subchondral sclerosis seen on recent radiographs, although we do not see a pathognomonic double line sign. We see no associated edema, subchondral fracture or articular surface collapse. There is patchy intermediate signal intensity within the distal femoral metadiaphysis and proximal tibial metadiaphysis which may reflect the sequela of end-stage renal disease. We see no focal articular cartilage defects. Chronic periosteal reaction along the distal femur and proximal tibia is again noted, which may reflect renal osteodystrophy, but we cannot exclude hypertrophic osteoarthropathy.LIGAMENTS: There is increased signal intensity and thickening of the lateral collateral ligament proper, suggesting degeneration. The MCL appears intact. The cruciate ligaments appear intact. EXTENSOR MECHANISM: There is diffuse thickening of the patellar tendon compatible with tendinosis, without a discrete tear. There is also thickening of the quadriceps tendon compatible with tendinosis. There is more focal signal abnormality within the lateral fibers of the quadriceps tendon at its insertion, which may represent focal tendinosis or perhaps a small insertional tear.ADDITIONAL
1. Poorly defined subchondral low signal intensity within the distal femur may reflect avascular necrosis, although we do not see a double line sign. There is no associated edema, subchondral fracture, or articular surface collapse.2. Patellar and quadriceps tendon tendinosis.