What Is the Meniscus?
The meniscus is a crescent-shaped wedge of thick, rubbery cartilage that is located between the shinbone (tibia) and the thigh bone (femur). The meniscus acts as a shock absorber, or cushion, for the knee joint during weightbearing, and prevents your femur and tibia from grinding against each other. The meniscus also helps to stabilize the knee during twisting motions. There are two pieces of meniscus in the knee. The medial meniscus is located on the inner side of the knee. The lateral meniscus is located on the outer side of the knee. Injuries to the medial meniscus are more common than injuries to the lateral meniscus.
How Does a Meniscus Tear Occur?
Tears in the meniscus vary in size, shape, and severity. Athletes most commonly tear the meniscus during a sudden twisting, pivoting, cutting or decelerating motion of the knee with the foot planted on the ground. Meniscus tears typically occur in sports that require running, cutting, and pivoting, such as basketball, football, and soccer. Meniscus tears can also occur with everyday activities, usually resulting from sudden twisting motions, or even from repeated kneeling or squatting. Older people can injure the meniscus without any trauma because the cartilage gradually wears thin and loses resiliency over time. As a result, a portion may break off, leaving frayed edges, which can generate symptoms.
What Are the Symptoms of a Meniscus Tear?
When the tear happens abruptly, there is immediate pain. Sometimes a "popping" sensation is felt when the meniscus is torn. Most people are still able to walk on the injured knee and many athletes are able to keep playing. Swelling typically is mild, and occurs later that day or the next day. Pain is usually localized to the side of the knee where the meniscus is injured, and is triggered by flexing or twisting the knee. If there is a loose piece of cartilage, it can get stuck in the joint, causing your knee to temporarily become locked in one position.
With a meniscus tear that develops over time, the onset of pain is typically more gradual, and is exacerbated by activities that put stress on the knee, such as squatting and twisting. The knee may also swell up and become stiff and tight.
How Is a Meniscus Tear Diagnosed?
Your sports medicine doctor will start by asking about your symptoms and examining your knee. This will provide some information about the condition of your meniscus. X-rays will not show an injury to the meniscus. An MRI (magnetic resonance imaging) is commonly used to confirm the diagnosis of a meniscus tear and to evaluate the condition of other structures within the knee joint. MRI is 70 to 90 percent accurate for diagnosing meniscus tears, so these findings along with your symptoms and physical examination will help the physician make a diagnosis. However, not all meniscus tears appear on MRI. Your physician may recommend arthroscopy to determine whether surgical repair or removal of the meniscus is needed. Arthroscopy is 100 percent accurate in diagnosing a true meniscus tear.
How Is a Meniscus Tear Treated?
Immediate treatment includes applying an ice pack for 20-30 minutes every 2-3 hours, and keeping the knee elevated as much as possible until the swelling is gone. An elastic bandage also helps to control the swelling. Crutches are recommended until you are comfortable bearing weight. Your doctor may prescribe some anti-inflammatory drugs such as ibuprofen. If your knee is stable and does not lock, this conservative treatment may be all you need. Blood vessels feed the outer edges of the meniscus, giving that part the potential to heal on its own. Small tears on the outer edges often heal themselves with rest and physical therapy. If your pain or swelling does not improve within six to eight weeks and a meniscus tear is suspected, your physician may suggest arthroscopy to better evaluate the injury.
What Are the Surgical Options for Treating a Meniscus Tear?
You may be a candidate for a meniscus repair if the tear is located on the outer portion of the meniscus, where the blood supply is better. These tears can be repaired more effectively than tears on the inner portion, where the blood supply is poor or non-existent. Since the menisci have been found to degenerate with age, an older person with a meniscus tear is a less likely candidate for repair. Patients over the age of forty tend to have tears with frayed surfaces that cannot be sewn back together. Meniscus repairs have a better long-term prognosis than a meniscus removal (partial or total meniscectomy). However, a longer rehabilitation is required after a meniscus repair than after partial or total meniscectomy. It will take at least 8-12 weeks before you can return to strenuous activity. There are different types of meniscus repairs. Your physician will choose the best technique based on the size and location of your tear and his or her experience with the techniques. All of the techniques have a reported success rate of 70 to 90 percent. Most repairs are done using an arthroscope. Small dart-like sutures are placed across the meniscus tear to hold it together. These are usually absorbed by the body over time.
If the tear cannot be repaired, the physician may recommend an arthroscopy to remove the torn portion. This is called a partial meniscectomy, and is a procedure commonly used for older patients. The goal of a partial meniscectomy is to eliminate pain and swelling by removing the injured part of the meniscus while saving as much of the healthy meniscus as possible. Partial meniscectomy is not as effective in patients with arthritis, and can take up to six months to rehabilitate, compared to 3-4 weeks if no arthritis is present.
Sometimes a large tear is best treated by arthroscopic total meniscectomy, a procedure in which the entire meniscus is removed.
Patients without arthritis who have had a total meniscectomy may be candidates for meniscal transplantation, which involves transplanting a meniscus from a cadaver knee.
What Kind of Rehabilitation Will I Need After Surgery for a Meniscus Tear?
You may need to use crutches during the first week. You will begin stretching and strengthening exercises as soon as possible after surgery, to keep the knee joint and surrounding muscles flexible. The goal is to strengthen the muscles of the lower limbs without putting too much strain on the meniscus. Most patients are able to return to work within a few days or a week after arthroscopic meniscus repair, provided work does not involve strenuous activity such as heavy lifting or climbing.
When Can I Return to Sports?
You will be able to return to sports activities when you have equal strength in both legs. This usually takes about two to four months.
Can Meniscus Tears Be Prevented?
Manage your weight. Every pound in excess of your normal weight puts three or four additional pounds of pressure on your knee every time you take a step. Strengthening the thigh muscles may help prevent further knee injury. Well-cushioned, well-fitting athletic shoes can reduce the impact of the load exerted on the knee.