If you would like to know more about the knee injury meniscus cartilage tear, its symptoms, diagnosis and treatment, read the following article for more information.
The menisci are cartilage tissue which act like shock absorbers in the knee joint. A meniscus can be torn, commonly after a forceful twisting injury to the knee. Symptoms include pain, swelling, clicking, and 'locking' of the knee. Some heal by themselves, but an operation to fix, trim or remove the torn meniscus may be advised.
Understanding joints
A joint is where two bones meet. Joints allow movement and flexibility of various parts of the body. The movement of the bones is caused by muscles which pull on tendons that are attached to bone.
Cartilage covers the end of bones. Between the cartilage of two bones which form a joint there is a small amount of thick fluid called synovial fluid. This fluid 'lubricates' the joint which allows smooth movement between the bones.
The synovial fluid is made by the synovium. This is the tissue that surrounds the joint. The outer part of the synovium is called the capsule. This is tough, gives the joint stability, and stops the bones from moving 'out of joint'. Surrounding ligaments and muscles also help to give support and stability to joints
The knee joint
The diagram below illustrates the knee joint. (For clarity it does not show the synovium, capsule or most of the surrounding muscles tendons and ligaments). The strong medial and lateral (inner and outer) collateral ligaments give a lot of support to the knee joint.
Knee Injury - Meniscus Tear
Features of the knee which are different to most other joints include:
- The knee joint consists of three bones - the femur (thigh bone), tibia (shin bone) and patella (kneecap). The patella is a small, oval shaped bone that lies in front of the other bones and slides when the leg moves. The patella helps to protect the knee, and gives leverage to the quadriceps muscles ('quads') which pull the leg straight.
- The menisci. Each knee joint contains a medial and lateral meniscus (inner and outer meniscus). These are thick 'rubbery' pads of cartilage tissue. They are C shaped and become thinner towards the middle of the joint. The menisci cartilage sit on top of, and are in addition to, the usual thin layer of 'articular' cartilage which covers the top of the tibia. The menisci act as 'shock absorbers' to absorb the impact of the upper leg on the lower leg, and help to improve smooth movement and stability of the knee. When people talk about a 'cartilage injury' to a knee, they usually mean an injury to one of the menisci.
- The cruciate ligaments. The supporting ligaments around most joints go over the outer capsule of the joint to join bones together, and give joints stability. For example, the medial and lateral collateral ligaments of the knee. In the knee, in addition, there are two strong ligaments within the knee joint itself - the anterior and posterior cruciate ligaments. These provide extra stability to the knee joint.
The rest of this page is just about meniscus injury. See separate pages for other knee problems.
Meniscus cartilage injury
You may tear a meniscus by a forceful knee movement whilst you are weight-bearing on the same leg. The classical injury is for a footballer to rotate (twist) the knee whilst the foot is still on the ground. He may do this, for example, whilst dribbling round a defender. Another example is a tennis player who twists to hit a ball hard, but with the foot remaining in the same position. The meniscus may tear fully or partially. How serious the injury is depends on how much is torn, and the exact site of the tear.
Meniscus tears may also occur without a sudden severe injury. In some cases a tear develops due to repeated small injuries to the cartilage, or to degeneration ('wear and tear') of the meniscus cartilage in older people. In severe injuries, other parts of the knee may also be damaged in addition to a meniscus tear. For example, you may also sprain or tear a ligament.
Meniscus cartilage does not heal very well once it is torn. This is mainly because it does not have a good blood supply. The outer edge of each meniscus has some blood vessels, but the area in the center has no direct blood supply (it is 'avascular'). So, some small outer tears may heal in time, but larger tears, or a tear in the middle of a meniscus, tend not to heal.
What are the symptoms of a meniscus tear?
- Pain. The pain is often worse when you straighten the leg. If the pain is mild, you may be able to continue to walk. You may have severe pain if a torn fragment of meniscus catches between the tibia and femur. Sometimes, an injury that you had in the past causes pain months or years later, particularly if you injure the knee again.
- Swelling. The knee may swell immediately if blood vessels are damaged with the injury. In some cases the swelling develops several hours after the injury if the joint fills with fluid as a result of inflammation caused by the tear.
- Knee function. You may be unable to straighten the knee fully. In severe cases you may not be able to walk without a lot of pain. The knee may click, or may 'lock' from time to time if the torn fragment interferes with normal knee movement. (A locked knee means that it gets stuck when you bend it, and you can't straighten it without manually moving or manipulating the leg.)
In some cases the symptoms of meniscus injury go away on their own after a few weeks. However, in many cases the symptoms they persist long-term, or flare up from time to time, until the tear is treated.
How is a meniscus tear diagnosed?
- The story and symptoms often suggest a meniscus tear. A doctor will examine the knee. Certain features of the examination may point towards a meniscus tear. For example, a doctor may bend the leg, then twist the leg slightly as he or she straightens the leg. During this movement, pain or a 'click' often indicates a meniscus tear.
- Your doctor may advise an x-ray of the knee. An x-ray does not show cartilage tissue, but can check for any bone damage which might have also occurred with the injury.
- The diagnosis can be confirmed by an MRI scan of the knee (see separate page on MRI scan) or by arthroscopy ('keyhole surgery' - see below.)
What is the treatment for a meniscus tear?
When you first injury your knee the initial treatment should follow the RICE formula: rest, ice, compression (with a bandage) and elevation. This, combined with painkillers, helps to settle the initial pain and swelling. Further treatment may then depend on the size of the tear, the severity of symptoms, how any persisting symptoms are affecting your life, your age, and your general health.
Non-operative treatment
Small tears may heal by themselves in time. Some tears which do not heal do not cause long-term symptoms once the initial pain and swelling subside, or cause only intermittent or mild symptoms. In these cases surgery may not be needed. You may be advised to have physiotherapy to strengthen the supporting structures of the knee such as the quadriceps and hamstring muscles.
Surgery
If the tear causes persistent troublesome symptoms then an operation may be advised. Most operations are done via an arthroscope (see below) but sometimes 'open' surgery to the knee is done. The sort of operations which may be considered include the following.
- In some cases the torn meniscus may be repaired and stitched back into place.
- In some cases repair is not possible and a small portion of the meniscus may be trimmed or cut out to even-up the surface.
- In some cases, the entire meniscus is removed.
- A meniscus transplant is a newer technique which is considered in some cases.
Arthroscopy is a procedure to look inside a joint by using an arthroscope. An arthroscope is like a thin telescope with a light source. It is used to light up and magnify the structures inside a joint. An arthroscope is passed through a small cut in the skin and into a joint. Most arthroscopic procedures are done on the knee joint.
In addition to simply looking inside, during an arthroscopy a doctor can use fine instruments which are also passed into the joint through a small incision in the skin ('key-hole surgery'). These instruments are used to cut, trim, biopsy, grab, etc, inside the joint. So arthroscopy can be used to diagnose and to treat meniscus tears. See separate page called 'Arthroscopy and Arthroscopic Surgery' for more details.
Following surgery you will have physiotherapy to keep the knee joint active (which encourages healing) and to strengthen up the surrounding muscles to give support and strength to the knee.
©EMIS and PIP 2004 Updated: June 2004 Review Date: July 2005 CHIQ Accredited
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