Locking. Loose bodies? MENISCI: The lateral meniscus appears intact. Seen on the short TE weighted images is a poorly defined oblique band of intermediate signal intensity traversing the posterior horn of the medial meniscus on a single image (e.g., image 14 of series 4); I suspect this has a low likelihood of representing a true tear and may be artifactual. The medial meniscus is otherwise unremarkable.ARTICULAR CARTILAGE AND BONE: There are large globular masses of heterogeneous signal intensity within the joint both anteriorly (e.g., adjacent to the anterior horns of both menisci, lateral greater than medial) and posteriorly (including along the popliteus muscle and tendon). The masses are predominantly isointense to skeletal muscle on T1-weighted images and hyperintense to skeletal muscle on T2-weighted images with small foci of low signal intensity internally. These masses correspond to calcification seen on the prior radiographs, and indicate primary synovial chondromatosis. The disease has progressed when compared to the prior MRI study from 2014. Multiple smaller "loose bodies" of cartilage are also noted within the joint.There is a full-thickness defect of the articular cartilage of the weightbearing portion of the medial femoral condyle measuring 6mm in greatest dimension and associated with subchondral cyst formation and edema in the underlying marrow. This is new when compared with the prior MRI study. There is also full-thickness degeneration of the articular cartilage along the medial facet of the patella superiorly with cyst formation and edema in the underlying marrow. This appears similar to that seen on the prior MRI study. I suspect that there is also superficial fraying of the articular cartilage of the femoral trochlea. The articular cartilage of the lateral compartment appears relatively intact.LIGAMENTS: The cruciate and collateral ligaments appear intact. EXTENSOR MECHANISM: The extensor mechanism appears intact.ADDITIONAL
Progression of synovial chondromatosis and cartilage degeneration as described above.