The medial meniscus is an important shock absorber on the inside (medial) aspect of the knee joint. It absorbs about 50% of the shock of the medial compartment. Thus, when there is a medial knee injury such as a medial meniscus tear, it is very important to try to repair the tear, because if not repaired and is trimmed out there will be an increase to the load on the medial compartment, which ultimately leads to osteoarthritis.
Description of Medial Meniscus Tear
A medial meniscus tear is more common than a lateral meniscus tear, because it is firmly attached to the deep medial collateral ligament and the joint capsule. In addition, the medial meniscus absorbs up to 50% of the shock of the medial compartment, making the medial meniscus susceptible to injury.
Medial meniscus tears appear in a variety of patterns:
• Displaced bucket handle
• Root detachments
• Parrot beak
• Displaced flap
Symptoms of a medial meniscus tear:
• Swelling and stiffness, increases gradually over 2 to 3 days
• Catching or locking
A complex tear of the medial meniscus includes a combination of any of the patterns listed above. In many circumstances in patients with these tears, the meniscus needs to be trimmed out. However, this does increase the risk of osteoarthritis, especially in patients who continue to participate in impact activities.
Longitudinal tear of the medial meniscus. (Click to Enlarge)
Double PCL Sign The double PCL sign is an MRI finidng that represents a bucket handle tear of the meniscus. As seen in the figure above, the meniscus is flipped inside the notch mimicking the look of the PCL. (Click to Enlarge)
How to Read a MRI of a Medial Meniscus Tear
Treatment for a Torn Medial Meniscus
Research has justified that patients with a certain age, with a proper environment, fairly normal articular cartilage, and neutral or near normal alignment, should have an attempt at a repair for medial meniscus tears. We believe that trying to stimulate an improved healing environment through the use of bone marrow elements, platelet rich plasma (PRP), and a large number inside-out meniscal repair sutures, can lead to improved ability to heal these tears, especially in younger patients.
The treatment for patients who undergo a partial medial meniscectomy is to initiate physical therapy on the first day after surgery. A treatment regimen working on reactivation of the quadriceps muscles, regaining of full knee and patellar mobility, and a quick resolution of knee swelling is emphasized. In general, we recommend that patients who have a minimal amount of meniscus trimmed out hold back on any impact activities until a minimum of 6 weeks after surgery. In patients who have a significant amount of meniscus resected, it is often recommended to avoid significant impact activities due to the higher risk of the development of osteoarthritis in these patients with this activity.
When a medial knee injury such as a torn medial meniscus needs to be resected, we strongly recommend that these patients be followed very closely. Patients need to report back to their physician if they have any pain or swelling with activities, because these are the signs of arthritis and may indicate further progression of arthritic changes. If this is present, further treatment to include activity modification, low impact exercising, unloader braces, injections, or possible meniscal transplantation may be indicated.
It is almost inevitable that when one has a significant amount of the medial meniscus resected that they will develop further arthritic changes over time. Because not everybody is the same, these changes can develop within a few weeks up to over a decade. Thus, one of the important things is to recognize that if one has any pain or swelling, they should follow up to make sure they are not developing any joint space narrowing or bone spurs, which would indicate that the medial compartment articular cartilage is wearing out.
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