Minnesota knee surgeon, Dr. Robert LaPrade discusses how to read an MRI of a meniscal root tear. The meniscal roots are the attachment sites for the meniscus to the bone, and are important because if detached can cause instability to the meniscus. Meniscal root tears have only been identified within the last five to six years, but new research has indicated the importance of identifying and repairing these type of injuries.
In this series of how to read a MRI of a meniscal root tear, this patient was very active and felt a pop in the back of the knee when squatting down and a few weeks later was unable to bare weight.
The first sequence of MRI scans in a coronal scan. Posteriorly, one of the first things present with a meniscal root tear is that the meniscus is not centered under the tibia and lays outside of the joint, this is known as extrusion.
As you move more posterior a bone fracture is developing due to the overload of on the articular cartilage because the meniscus is not laying properly. The normal attachment on the tibia is more squared off, which is consistent with the appearance of a meniscal root tear.
The next image is a sagittal view, which shows fluid in the back of the knee where a Baker’s cyst is developing. This view is used to identify a ghost sign.
The final image is an axial view, which gives the best assessment of a meniscal root tear. Starting at the patella, you can see a lot of the swelling within the joint. As you get to the joint line you can see a disruption of the meniscus attachment site.