Case 32 - 20 year old male with right knee injury while playing basketball
20 year old male with right knee injury while playing basketball.
Case discussion:- This case has many findings; it's helpful to use a checklist and be systematic to ensure an important finding doesn't get missed.
- We can see a small joint effusion with synovitis, but the ACL, PCL, and MCL all appear intact.
- We do, however, see a large amount of fluid in the lateral soft tissues on the fluid-sensitive sequences, as well as a small amount of marrow edema in the lateral femoral condyle.
- This area of the knee, specifically the group of ligaments and tendons, which insert on the fibular head are referred to as the posterolateral corner or arcuate complex. This degree of fluid indicates a high grade posterolateral corner injury, although it's important to note that the fibular collateral ligament, conjoint tendon, and popliteus tendon fibers appear intact.
- Can you spot all of the additional findings? The complex tear of the lateral meniscus? The partial tear of the anterolateral joint capsule? The large area of full thickness cartilage loss on the lateral femoral condyle?
Expert commentary:- Note the course and appearance the fibular collateral ligament. It arises from the lateral femoral condyle and inserts on the fibular styloid, however, unlike the medial collateral ligament, the fibers do not insert on the underlying meniscus.
- The anatomy of the posterolateral corner is highly variable and discrete structures are not always identifiable. Often the only sign of a posterolateral corner injury is fluid and edema around the posterolateral joint capsule.
- High-grade posterolateral corner injuries are important to identify because they can lead to instability, even in isolation. They are typically repaired surgically.
Accession: CL0091
Study description: MR KNEE RIGHT
