Case 44 - 48 year old male with left knee pain
48 year old male with left knee pain.
Case discussion:- This patient has a small joint effusion with a thin medial plica. There is also a small Baker cyst, which may have ruptured given all of the soft tissue edema tracking down the posterior musculature. Baker cysts can be extremely painful when they rupture, however, we should avoid satisfaction of search and inspect the remaining structures.
- On axial images the medial meniscus appears abnormal with high signal throughout the body and posterior horn, as well as a suggestion of a vertical longitudinal tear.
- On coronal and sagittal images we can actually appreciate that this represents a large complex tear of the medial meniscus.
- Components of the free edge and inferior articular surface appear truncated. The body appears ball-like and is mildly extruded. The tear has multiple oblique components extending through the inferior articular surface. There's even a likely parameniscal cyst near the posterior root, suggesting extension through the posterior root, even though we don't see a discrete tear.
Expert commentary:As previously mentioned, parameniscal cysts are a helpful diagnostic clue. Even though the posterior root adjacent to the cyst appears normal, the presence of the cyst suggests the tear may extend further into the root than visualized on the MRI. The other diagnostic possibility for this cystic structure is a posterior cruciate ligament ganglion. These lesions are frequently seen incidentally, even in the setting of a normal appearing PCL, such as this one; they occur as a result of prior injury to the PCL.
Accession: CL0088
Study description: MR Knee Left
