Knee pain after ski injury There is curvilinear low signal intensity within the posterior aspect of the lateral tibial plateau with surrounding edema, indicating a fracture. The fracture extends to the articular surface beneath the posterior horn of the lateral meniscus and also extends through the overlying articular cartilage. The resultant fragment is approximately 1 cm in AP dimension, 6 mm in depth (not including the overlying articular cartilage) and 2 cm in mediolateral dimension. The fracture fragment is nondisplaced. I see no additional fractures and the remainder of the articular cartilage appears normal. The majority of the lateral meniscus appears intact; however, there is increased signal intensity traversing the posterior horn near its root attachment which, given its proximity to the aforementioned fracture, likely represents a small peripheral tear. There is poorly defined increased globular signal intensity within the posterior horn and body of the medial meniscus suggesting intrasubstance degeneration. Additionally, there is horizontally oriented linear signal abnormality within the posterior horn and body of the medial meniscus that appears to contact the femoral articular surface on a single image; statistically, this finding has an approximately 40% chance of representing a true tear. The anterior horn of the medial meniscus appears normal. The cruciate and collateral ligaments are intact. The extensor mechanism is intact. There is a moderate-sized joint effusion. There is a lobulated collection of heterogeneous signal intensity adjacent to the posterior margin of the medial aspect of the distal femoral metaphysis, with extension laterally anterior to the popliteal vessels. Overall the collection is approximately 3 x 1 cm in cross-sectional and 2 cm in craniocaudal dimension. This collection contains components that are isointense to fat on all imaging sequences. Given the aforementioned fracture, I suspect that it represents blood and marrow elements that have migrated through the fracture into the subgastrocnemius recess.
Acute osteochondral fracture of the posterior aspect of the lateral tibial plateau as described above. I suspect that this is associated with a small peripheral tear through the posterior horn of the lateral meniscus near its root attachment. Other findings as described above.