Case 26 - 22 year old male with knee pain
22 year old male with right knee pain.
Case discussion:- This patient has no significant joint effusion, contusions or edema to suggest an acute injury.
- The distal portion of the posterior cruciate ligament appears thickened with intermediate signal intensity. On axial images, we can better appreciate that this abnormality only involves the posteromedial portion of the PCL.
- An associated ganglion cyst calls attention to the abnormality.
- A second smaller ganglion cyst associated with the proximal ACL draws attention to subtle signal abnormality of the adjacent ligamentous fibers, which appear intact.
- These findings are compatible with a chronic tear of the posteromedial bundle of the PCL and a mild sprain of the ACL.
Expert commentary:The PCL has two bundles: the larger anterolateral bundle and the smaller posteromedial bundle. This case illustrates that the two bundles may be injured in isolation. Both bundles originate on the anterolateral aspect of the medial femoral condyle and inserts posterior to the tibial plateau, outside of the joint. On the sagittal PD images note that the PCL is approximately double the length of the ACL; on axial PD images note that the PCL is also nearly twice the thickness of the ACL. Lastly, note that the ACL also has two bundles: the smaller anteromedial band and the bulkier posterolateral band. These originate from the posteromedial aspect of the lateral femoral condyle and inserts over a broad portion of the anterior tibial plateau, anterior and lateral to the tibial spine, within the joint. All of the descriptors for the ACL and PCL are opposite one another, which can get confusing.
Accession: CL0075
Study description: MR Knee Right
