Meniscus tears are a common knee injury. Some patients have tears that cause few problems, while others have tears that cause pain and inability to do sports or work. Treatment ranges from non-operative to surgical, depending on multiple factors, including age, type and location of tear, symptoms, presence of arthritis, and patient goals.
There are two menisci in your knee. One is on the inside (medial) and one is on the outside (lateral). Injuries can occur to either meniscus, or sometimes to both at the same time. They are both rubbery wedges which are shaped like a “C.” They are about 3 centimeters wide in adults and 3-5 centimeters long. The menisci are situated between the thigh bone (femur) and the shin bone (tibia). They are important structures, which serve as cushions and shock absorbers in the knee.
The menisci were once thought to be irrelevant structures serving no useful purpose. As recently as the 1970s, if you had a meniscus tear, the treatment was simply to remove the entire meniscus, usually through an open incision. Subsequent follow-up studies on these patients who underwent complete removal showed that a very high percentage of them developed arthritis.
It is now clearly understood that the meniscus protects articular cartilage in the knee from deterioration, so emphasis is placed on maintaining as much functional meniscus tissue as possible.
Meniscus tears occur as a result of trauma or from repetitive wear-and-tear (degenerative tears). Tears in younger people tend to be related to trauma, often a forceful twisting event. Associated injuries may occur, such as anterior cruciate ligament (ACL) tears. In the setting of trauma, patients typically have acute pain, swelling in the knee and difficulty bearing weight. In some cases, the tear involves a very large portion of the meniscus and it flips over on itself inside the knee, causing the knee to lock up. This is called a bucket handle tear.
Degenerative tears are usually seen in older individuals. Many patients with degenerative tears also have some amount of cartilage damage. Patients generally complain of pain along the side of the knee where the meniscus tear is located, and pain may be exacerbated by bending or twisting the knee. Swelling, clicking and catching are other common complaints. Often the symptoms are intermittent and only occur with certain activities. Sometimes the pain affects the ability to sleep at night.
The diagnosis can usually be made by taking a good history and performing a thorough knee examination. The main physical examination finding is tenderness over the joint line on the inside or outside of the knee, depending on where the tear is located. A complete ligamentous examination should also be performed, especially in the setting of trauma, to rule out other injuries like an ACL tear.
X-rays are often performed to evaluate for fractures in the setting of trauma, or pre-existing arthritis. MRI may be helpful for confirming the presence of a meniscus tear as well as evaluating ligaments and articular cartilage.
Acute, traumatic tears, are typically treated surgically. The goal is to try and repair the meniscus, if at all possible. This is done by placing stitches through the meniscus. There are a variety of techniques to do this. Meniscus repairs are now done arthroscopically (another word for a minimally invasive surgical procedure), although small, open incisions may be used in conjunction with an arthroscopic approach. Typically, the results of meniscus repair are better in younger patients with acute traumatic tears in areas of the meniscus that have a good blood supply. Unrestricted return to sports is usually between four and six months after surgery.
If a tear cannot be repaired, a trimming (meniscectomy) may be performed. This is a very common orthopaedic procedure, which is performed arthroscopically. This procedure can be very effective in relieving symptoms, however, there currently exists some controversy as to whether doing surgery for a degenerative meniscus tear, especially in the setting of underlying arthritis, has any benefit over non-surgical treatment in the long-term. Surgery is often not the first treatment for degenerative tears. Other options include anti-inflammatory medication, physical therapy, and cortisone injections. Sometimes, symptoms simply improve on their own with time.
In younger patients who have a large tear that is not repairable or who have undergone a repair that has failed, a meniscus transplant may be considered, especially if the patient is having pain and swelling. This involves placing an entirely new meniscus from a donor into the knee. This has been shown to be effective at reducing pain but has not been shown to prevent the development of arthritis by protecting the cartilage.
Current research involves the use of stem cells and other types of biologic augmentation to improve the rate of healing of meniscus tears. Additional research is aimed at the use of scaffolds and other types of meniscal replacements to treat meniscal deficiencies.
Nathan Endres, MD, is an orthopaedic surgeon at the University of Vermont Medical Center and assistant professor at UVM. He is fellowship trained in sports medicine, shoulder surgery and orthopaedic trauma. He is a former ski racer and member of the United States Ski and Snowboard Assocation (USSA) physician pool.