One of the most common of knee injuries is a meniscal tear.
The two pieces of cartilage in the middle of the knee, the menisci, are tough, rubbery pads of material that help absorb shock during motion and cushion the knee. They also keep the thighbone (femur) and the shinbone (tibia) from rubbing against each other. There are two menisci in the knee, the medial and lateral.
When one of the menisci is partially torn, it will usually stay connected to the front and back of the knee. If a tear is large, the meniscus may just be left hanging by a small piece of tissue.
What causes a meniscal tear?
There are two causes of a meniscal tear:
1. The most common reason for a tear is when the knee rotates at the same time it is bearing weight. In other words, a person quickly twists or rotates the upper leg while the foot stays still. This pivoting type of injury is more common in certain sports, such as when a basketball player turns to dribble around an opponent, a tennis player turns to hit a ball, or a football player quickly changes the direction of a run.
2. Meniscal tears also can result from age-related degeneration. The menisci can become weak, worn and thin over time, making them more susceptible to tearing during everyday activities, such as when rising from a squatting position.
What are the symptoms of a meniscal tear and how is it diagnosed?
People experience different symptoms, depending on the severity of the tear. Symptoms may include one or more of the following:
- A popping sensation in the knee at the time of the tear.
- Swelling around the entire knee joint.
- Pain and tenderness in the joint.
- An inability to completely straighten or bend the knee (may be a result of the swelling or because a flap of the torn meniscus has drifted into the joint).
- Continued popping, locking or buckling of the knee after the injury.
If, after a thorough examination, an orthopaedic surgeon believes a meniscal tear is likely, a magnetic resonance imaging (MRI) scan is performed to confirm a suspected tear. Unlike an X-ray, which only shows bony structures, an MRI allows the orthopaedic surgeon to view detailed images of the soft tissues in the knee, including the knee’s cartilage. An MRI scan is a painless, outpatient test that has no known side effects or dangers.
How is a meniscal tear treated?
Most meniscus tears do not heal on their own, so they must be treated surgically. No medicines, braces or physical therapy treatments are available to promote self-healing of tears.
While waiting for surgery, some non-surgical treatments may be suggested to alleviate discomfort. Those treatments may include the following:
- RICE–rest, ice, compression and elevation.
- Anti-inflammatory medications.
- Physical rehabilitation of the knee with exercises to strengthen the muscles supporting the knee and stretches to improve the knee’s range of motion.
In most cases, the surgeon will use arthroscopic surgery to treat a meniscal tear. Arthroscopic surgery makes use of a fiberoptic scope connected to a video camera and small, specialized instruments. In this procedure, the scope and instruments are inserted into small puncture-type incisions rather than through a larger open incision. This surgery is usually performed on an outpatient basis and does not require an overnight stay in a hospital. In rare cases, arthroscopic surgery is not feasible and the surgeon must make an incision to open the knee.
Patients may have one of several types of surgeries for a tear. Those options include:
- Partial meniscectomy: The torn section of the meniscus is removed and the edges of the remaining meniscus are smoothed.
- Total meniscectomy: The entire meniscus is removed.
- Surgical repair: The torn meniscus is sewn together. However, the majority of tears are not able to be repaired this way and require at least a partial meniscectomy.
Orthopaedic surgeons prefer to remove only the damaged part rather than the entire meniscus. Saving as much cartilage as possible may reduce or delay the onset of future knee joint degeneration and osteoarthritis.
Some medical researchers have done work with new procedures. In an allograft, for example, the removed meniscus is replaced with an implant from a donor cadaver. Researchers have also been working to develop an artificial meniscus.
After surgery, a patient must complete rehabilitation exercises to build up leg muscles and increase knee flexibility.