Tear of meniscus

In sports and orthopedics, people will sometimes speak of "torn cartilage" and actually be referring to an injury to one of the menisci. Menisci can be torn during innocuous activities such as walking or squatting. They can also be torn due to traumatic forces encountered in sports. The trauma mechanism is most often a twisting movement while the knee is bent. In older adults, the meniscus can be damaged following prolonged 'wear and tear'; this is called a degenerative tear.

Tears can lead to pain and/or swelling of the knee joint. Especially acute injuries (typically in younger, more active patients) can lead to displaced tears which can cause mechanical symptoms such as clicking, catching, or locking during motion of the knee joint. The joint will be in pain when in use, but when there is no load, the pain goes away.

A tear of the medial meniscus can occur as part of the unhappy triad, together with a tear of the anterior cruciate ligament and medial collateral ligament.

Symptoms and signs
The patient's chief complaints are usually knee pain and swelling. These are worse when the knee bears more weight (for example, when running). Other typical complaints is joint locking, when the patient is unable to fully straighten the leg. This can be accompanied by a clicking feeling. Sometimes, a meniscal tear also causes a sensation that the knee gives way.

The patient can sometimes remember a specific activity during which the injury was sustained. A tear of the meniscus commonly follows a trauma which involves rotation of the knee while it was slightly bent. These manoevers also excite the pain after the injury; for example, getting out of a car is often reported as painful.

After noting symptoms, a physician can perform clinical tests to determine if the pain is caused by compression and impingement of a torn meniscus. The knee is examined for swelling. In meniscal tears, pressing on the joint line on the affected side typically produces tenderness. The McMurray test involves pressing on the joint line while stressing the meniscus (using flexion-extension movements and varus or valgus stress). Similar tests are the Steinmann test (with the patient sitting) and the Appley test (a grinding manoever while the patient lies prone and the knee is bent 90°). Bending the knee (into hyperflexion if tolerable), and especially squatting, is typically a painful manoever if the meniscus is torn. The range of motion of the joint is often restricted.

Also see: Bounce Home Test, Thessally's Test, Wilson's Test (internal/external rotation), and Bohler's Test.

Diagnosis
X-ray images (normally during weightbearing) can be obtained to rule out other conditions or to see if the patient also has osteoarthritis. The menisci themselves cannot be visualised with plain radiographs. If the diagnosis is not clear from the history and examination, the menisci can be imaged with magnetic resonance imaging (an MRI scan). This technique has replaced previous arthrography, which involved injecting contrast medium into the joint space. In straightforward cases, knee arthroscopy allows quick diagnosis and simultaneous treatment.

Treatment
The treatment course is dependent on the needs and status of the patient. A conservative course of treatment involving just physical therapy is possible. The patient will probably have to take a small break from his or her normal activities, allowing the knee to heal. Exercises can strengthen the muscles around the knee, especially the quadriceps. Stronger and bigger muscles will protect the meniscus cartilage by absorbing a part of the weight. The patient may be given paracetamol or anti-inflammatory medications.

If this does not resolve the symptoms or in cases of a locked knee, then surgical intervention may be required. Depending on the location of the tear, a repair may be possible. In the outer third of the meniscus, an adequate blood supply exists and a repair will likely heal. Usually younger patients are more resilient and react well to this treatment, while older, more sedentary patients do not have a favorable outcome after a repair.

The meniscus has fewer vessels and blood flow towards the unattached, thin interior edge. In the majority of cases, the tear is far away from the meniscus' blood supply, and a repair is unlikely to heal. In these cases arthroscopic surgery allows for a partial meniscectomy, removing the torn tissue and allowing the knee to function with some of the meniscus missing. In situations where the meniscus is damaged beyond repair or partial removal, a total menisectomy is performed. This option is avoided at all costs as total meniscectomy leads to an increased risk of osteoarthritis (with loss of cartilage) and eventual total knee replacement. In some cases, a meniscus replacement is done to prevent this.

Rehabilitation after meniscus surgery
After a successful surgery for treating the destroyed part of the meniscus patients must follow a rehabilitation program to have the best result. The rehabilitation following a meniscus surgery depends on whether the entire meniscus was removed or repaired.

If the destroyed part of the meniscus was removed, patients can usually start walking a day or two after surgery. Although each case is different, patients return to their normal activities on average after a few weeks (2 or 3).

If the meniscus was repaired the rehabilitation program that follows is a lot more intensive. After the surgery a hinged knee brace is placed on the patient. This brace allows controlled movement of the knee. The patient is encouraged to walk using crutches from the first day, and most of the times can put weight on the knee. The time course varies with each patient, but roughly after four weeks the patient can start walking using the hinged knee brace only. Starting from the second month the patient can walk freely and can also do various "light" exercises (static bicycle, swimming, etc.). If the rehabilitation was done properly the patient can gradually return back to "heavier" activities (like running).