Description of a Lateral Meniscus
The lateral meniscus is an essential shock absorber on the outside (lateral) aspect of the knee joint. It absorbs about 70% of the shock of the lateral compartment. Lateral meniscal tears are not as common as medial meniscus tears. This is because the lateral meniscus is more mobile and not secured as much to the lateral tibial plateau as the medial meniscus is to the medial tibial plateau. Thus, when there is a lateral knee injury such as a lateral 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 lateral compartment, which ultimately leads to osteoarthritis.
Symptoms of a lateral meniscus tear:
• Swelling and stiffness, increases gradually from hours to days after injury
• Catching or locking
• An inability to straighten the knee
Treatment of a Lateral Meniscus Tear
Due to the added shock absorbing capacity of the lateral meniscus, it is essential to attempt to repair lateral meniscus tears if possible. 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 lateral 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 lateral 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 torn lateral 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 lateral 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. We have observed that this often can develop rapidly in younger patients. 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 lateral compartment articular cartilage is wearing out.