The meniscus is one of the most commonly injured structures in the knee and the knee is one of the most frequently injured joints in the body. You can get meniscus injuries at any age because of the anatomy of the meniscus.
Meniscus surgery is a common orthopedic surgery. For example, surgeons do arthroscopic medial meniscectomies, or using minimally invasive surgery to cut out part of the meniscus, over half a million times per year.
Anatomy
There are two menisci (the plural of meniscus) in the knee. The lateral meniscus is more circular and the medial meniscus is a C shape. Both are attached at the front and back of the knee. The way they are attached means that the knee is able to move easily, which is great for doing activities where you need a lot of motion but means your knee is more likely to be injured.
The meniscus starts off tough and becomes more brittle and easily torn as you age. When you’re young, it takes a traumatic event such as an ACL tear or other high-energy sports injury to tear the meniscus. In an older person, just squatting to pick up something off the floor can cause a tear.
The meniscus has two main functions: weight bearing and stability. When you put weight on your leg, the meniscus supports and distributes the forces generated. The meniscus also helps stabilize your knee and keep it in position.
Tears and symptoms
The meniscus can tear in many ways and locations, and some of the tears are worse than others. One type is due to age wearing down the edge of the meniscus and doesn’t usually cause symptoms. Another type can tear the meniscus enough that your body acts like there’s no meniscus. A third type can create a flap of meniscus, which can get stuck in the knee and cause pain. One meniscus can have multiple tears at the same time.
Meniscus tears in younger people are usually associated with trauma, such as a sports injury or slipping off a ladder. In younger people the tears are often smaller and cleaner. As you get older and the meniscus gets more brittle, the meniscus is more likely to tear from everyday activities such as a misstep while running or squatting to pick something off the ground and the tear is more likely to be severe.
You may not have symptoms right away if the tear is a clean tear toward the outside. You only have pain from a meniscus tear if it moves and causes symptoms in the knee, so if the meniscus doesn’t move out of position right away you may not know that it has torn.
The classic example of meniscus pain is from a flap tear. As you walk and otherwise move around, the flap can move around and get stuck in the knee joint. The knee will feel uncomfortable and you may have pain. Having a torn meniscus puts stress on your knee, so you may also have pain from your bones.
The meniscus blood supply only makes it to the outer third of the meniscus. Since blood flow is necessary for healing, a tear on the inside of the meniscus is unlikely to heal on its own. One of the goals of treating meniscus tears is to create a way to get blood to the torn part of the meniscus so it can heal.
The pain is often just on one side of the knee or the other, and there may be swelling. The symptoms may come and go depending on if the meniscus is out of position or in position.
Diagnosing
The symptoms of a meniscus tear and of other injuries to the knee can overlap, and a single incident can cause injury to other parts of the knee as well. Knee pain should be checked out to see what the cause is.
X-rays are a common first step with knee pain. The x-rays can show if you have arthritis in your knee. Knees with arthritis are unlikely to have much success with meniscus treatment, because the meniscus has probably already been damaged like the cartilage has been damaged.
Your doctor will see if you have swelling in your knee. They will put pressure on the knee, try to move any fluid around the knee, and feel the knee. They will see if there’s sensitivity or tenderness, another sign of a meniscus tear.
Additionally, the doctor may straighten or bend your leg all the way. They are looking to see if the movement causes pain and if the pain is in the same spot.
One of the most sensitive tests is the McMurray’s test, where the doctor twists the leg to grind it back and forth and put pressure on the different parts of the meniscus. If there’s clicking or pain, a meniscus tear is likely.
Treatment
Treatment starts off with RICE – rest, ice, compression and elevation – and anti-inflammatory medications. If you’ve had symptoms for more than three to six weeks, your x-rays don’t show arthritis and the office tests show that a meniscus tear is likely, you may get an MRI so the doctor can see inside your knee and plan for a treatment. The MRI can show the specific type of tear and the location of the tear. The treatment plan will be based on your own condition. For instance, if you have a lot of pain in your knee and the MRI shows you have a bone bruise, you might be put on crutches, given physical therapy exercises, and allow the bone to heal for several weeks first. If you still have symptoms, then additional treatment for the meniscus may be needed.
How well the meniscus will heal depends on the symptoms and the age, activity level, weight, and health of the patient. For example, if you have arthritis in your knee, you can have meniscus surgery but it may not help your symptoms to improve. On the other hand, doing an ACL repair at the same time as a meniscus repair increases the odds of healing your meniscus by at least 10%. Your doctor will talk with you about the best choices for you.
Surgery
Meniscectomy
The meniscectomy is the most frequent meniscus surgery. The goal of the meniscectomy is to remove the damaged tissue and save as much of the normal tissue around it as possible. The meniscectomy is used when the tear is in the part of the meniscus unlikely to heal because it does not have a good blood supply.
After a period of healing, most people recover well from a meniscectomy and can go back to their normal activities. The time you need to heal may be longer than you think, but if you go back to activities too soon you can damage your knee. You may or may not need physical therapy after a meniscectomy.
Repair
With a repair, the surgeon is trying to restore the meniscus anatomy and meniscus function.
Suturing, or stitches, is the most basic type of meniscal repair. There are several different ways to put the stitches into the meniscus, and there are specialized tools that allow the sutures to be put precisely where they’re needed. Which type of suturing is chosen depends on where the tear is in the knee.
After a repair, you’ll be on crutches for at least four to six weeks, and you may not be allowed to bend your leg much while it heals. Because you’re just working with soft tissue, not bone, it takes longer to heal than many other knee surgeries. It may take several months before you can run and jump on it safely again.