The knee is made up of three bones: the thighbone (femur), the shinbone (tibia), and the kneecap (patella), as well as the soft tissue that connects them. Between your femur and your tibia are two C-shaped discs of cartilage. They act as shock absorbers for the bones and help keep your knee stable. These C-shaped discs are your menisci (plural of meniscus). They can be torn, particularly if the knee twists suddenly while it is bent.
Viewed from the front or back, the meniscus is wedge shaped. This shape helps keep the rounded surface of your femur from sliding off the flat top of your tibia. The outer edges of this wedge receive a good supply of blood, and tears in this part of the meniscus heal well on their own. But the inner part of the meniscus has no direct blood supply to help it heal. Tears in this area might need surgery.
A torn meniscus is a common sports injury, particularly in contact sports like football and hockey. Meniscus tears can range from minor to severe, depending on the extent of the damage, and they can make it difficult for the knee to function properly.
Older people often get meniscus tears because their menisci become brittle and less flexible with age. But for teens, meniscus tears usually happen because of an injury — often after twisting or turning the knee while it is bent and the foot is firmly planted. This might happen when:
- Lifting heavy objects
- Making sudden changes in direction or slowing or stopping quickly, as can happen in sports like soccer, baseball, basketball, tennis, and racquetball
- Taking a direct hit to the knee while playing a contact sport, such as football, hockey, or rugby, where the knee may be forced to twist or turn awkwardly
- Falling in a way that puts a lot of strain on the knee during a fall, as can happen in sports like skiing or snowboarding
Meniscus tears often happen along with other knee injuries such as ligament tears.
The symptoms of a torn meniscus will vary depending on the severity of the tear. Someone who gets a minor tear may only have slight pain and swelling that goes away after 2 or 3 weeks.
Moderate to severe tears also might cause these symptoms:
- A "pop" in the knee when the tear occurs
- Pain in the center or side of the knee, especially when twisting the knee or squatting. This will usually go away after a couple of weeks but can come and go for much longer if the tear is not treated.
- Swelling and stiffness in the knee that gets worse over the first 2 or 3 days after the injury occurs
- Limited range of motion
- The knee feeling as if it is locking or popping when bending; it might not straighten
- The knee feeling like it is giving way without warning
If you see a doctor about pain in your knee, he or she will ask how you injured it and what it feels like. The doc will also review your medical history to see if the pain might be caused by something other than a torn meniscus.
The doctor will examine your knee to see if you have any tenderness in the area where your meniscus sits. To see if pain is caused by a meniscus tear, a doctor might ask you to squat. The doctor might also bend, straighten, and rotate your knee.
The doctor also might order an X-ray to check for other conditions that can cause knee pain or a magnetic resonance imaging (MRI) scan to get a better look at the soft tissue of your knee. X-rays and MRIs are the best way to "look" inside the knee without doing surgery.
Minor tears usually don't need surgery, especially if they are on the outer part of the meniscus where there is a good supply of blood. These tears should heal on their own fairly quickly. Treatment can include the following:
- Use the RICE formula:
- Rest: Stop doing the activity that caused the injury, and give your knee plenty of time to rest. In some cases, this may involve using crutches to keep weight off your knee while it recovers.
- Ice: Apply ice or a cold compress to your knee several times a day for 15 minutes at a time until the pain and swelling go down. Wrap ice or ice packs in a towel. Don't put them directly on the skin as this can cause tissue damage.
- Compression: Use an elastic compression bandage to keep swelling down and help support your knee.
- Elevation: Lie down and put pillows under your knee to raise it above the level of your heart. This will help keep swelling to a minimum.
- Take anti-inflammatory medications. Painkillers such as acetaminophen and ibuprofen can help relieve pain and reduce swelling in the affected area.
- If your doctor prescribes it, do physical therapy. PT can help you strengthen your leg muscles, stabilize your knee, and get your knee back to its full range of motion and flexibility.
For severe tears or tears that don't respond to other forms of treatment, a doctor may have to perform surgery. Usually, this will be in the form of arthroscopic surgery, where a small camera is inserted into the knee to help surgeons see what they're doing without having to open the knee up.
Sometimes a surgeon can repair a torn meniscus. Other times, the surgeon will trim away the torn piece of the meniscus to stop it from interfering with the way the knee works. If you get surgery, the doctor may put your knee in a brace afterwards. This keeps the knee from moving around it while it heals. You might need to use crutches for a while.
As with any sports injury, the key to healing meniscus tears — no matter how minor — is not to get back into play too quickly. Your body (and performance) will be stronger if you wait until your doctor gives you the OK to get back in the game.
Because they generally happen without any warning, meniscus tears can be hard to prevent. You can reduce your risk, though, by taking these precautions:
- Get regular exercise, including strength training for your leg muscles. Strong leg muscles help stabilize and protect the knee.
- Always warm up and stretch properly before playing sports or engaging in any strenuous activity involving your legs.
- Give your muscles plenty of time to rest and recover between activities.
- Get the right footwear for your sport, and keep shoes, boots, or skates laced up tight while you play.
- Learn and use the proper techniques for your sport.
- If you've previously had another knee injury, a brace or wrap can give your knee added support.