Minnesota knee specialist Dr. Robert LaPrade discusses how to read an MRI of a normal knee. Anatomy of the knee can be complicated and hard to understand. Through the use of magnetic resonance imaging, clinicians can diagnose ligament and meniscal injuries along with identifying cartilage defects, bone fractures and bruises.
To begin, we use a coronal scan of a left knee. A coronal scan goes through the knee, front to back, with the dimensions being medial to lateral. To begin a coronal scan the patella is at the center. As the image moves deeper you can begin to see the quadriceps tendon and the patellar tendon below. We then move to the tibiofemoral joint. The medial and lateral meniscus come into view and the IT band on the side.
As the image moves deeper you can begin to see the medial collateral ligament along the tibia and the anterior cruciate ligament. On the lateral side of the knee the fibular collateral ligament. The ACL becomes more clear as you more deeper into the knee. The medial and lateral meniscal root attachments begin to appear. As we move more posterior aspect of the knee you can see the biceps femoris. Clinically, the coronal view is used to identify any medial or lateral meniscus injuries.
The next image used is the sagittal views. The sagittal views look at the knee from front to back. You can clearly see the posterior and anterior horn of the lateral meniscus. The gray area around the bone is the articular cartilage. As we get more central in the joint, we can begin to see the patellar tendon. The ACL and PCL also come into view. As we move to the far medial aspect we will start to see the hamstring tendons.
The last view is the axial view, which is like cutting through a log. As the image moves deeper into the knee you can see the outline of the menisci. We look for any ghost signs that may appear for radial tears. You can see the shiny white fibers of the posterior horn of the medial meniscus.