Ask The Physician

Meniscus Tears & Shoulder Instability

Answers to Your Health Questions by Mark A. Pollard, M.D.

Q: What is a meniscus?

A: A meniscus is a “C” shaped wedge of cartilage located between the tibia and the femur in the knee joint. One meniscus is on the inside (medial meniscus) and one meniscus on the outside (lateral meniscus) of the knee. These cartilage wedges serve two purposes in the knee: a shock absorber and stabilizer. The meniscus can become torn and cause pain.

Q: How does a meniscus tear happen?

A: Typically, meniscus tears occur with twisting injuries of the knee. They also commonly occur at the same time as knee ligament injuries (ACL, PCL or MCL).

Q: How do I know if I have a meniscus tear?

A: Most meniscus tears cause pain that localizes to one side of the knee. There is often a history of knee clicking, popping, catching, or locking. A locked knee–a knee that won’t move–is the most serious of these symptoms and should warrant a trip to a doctor as soon as possible. Often, knee swelling will accompany meniscus tears. Physicians diagnose meniscus tears with a combination of a physical examination, X-rays (which don’t show meniscus tears but do show arthritis) and an MRI. One important item to try to determine is whether the pain is coming from arthritis or from a meniscus tear—both are commonly present in some people.

Q: How is a meniscus tear treated?

A: Every meniscus tear is different. Many things are factored into choosing the appropriate treatment: tear size, tear location, tear shape, patient’s age and the condition of the meniscal tissue. Some tears are treated with repair using stitches or staples to put the torn pieces back together. In very rare situations, meniscal replacement surgery can be performed. For the vast majority of meniscus tears, the best treatment is careful resection of the torn part of the meniscus. Most of these surgeries can be performed with an arthroscopic procedure–an outpatient surgery typically involving two or three ¼ inch incisions. After these sorts of procedures, patients tend to do very well.

Q: What is shoulder instability?

A: Shoulder instability refers to an irregular motion relationship of the ball of the shoulder joint (the head of the humerus bone) to the cup of the shoulder joint (the glenoid and labrum: which, together, look like a golf tee lying on its side). Under normal circumstances, the ball is well centered in the glenoid by a combination of factors: muscle function, ligament function, and bony anatomy. When one or more of these factors isn’t functioning properly, the ball may become uncentered, or may even fall out of the glenoid–a condition called shoulder dislocation.

Q: How does shoulder instability occur?

A: Most people have a history of having a traumatic event to the shoulder. Many have a history of a dislocation that required someone else to reduce it–pop the shoulder back into place. Some people have a history of repetitive motions that can lead to instability. The end result of these situations is the dysfunction of the labrum (a cartilage ring around the rim of the glenoid that makes the cup-like shape deeper), fracture of the bone, or rupture or stretch of the ligaments that normally hold the shoulder in place.

Q: How do I know if I have shoulder instability?

A: Sometimes instability is obvious, as in a case of a shoulder that repeatedly dislocates and must be put back into place. Sometimes the symptoms of shoulder instability are more subtle: the feeling of being unable to “trust” the shoulder, “popping” of the shoulder or sudden weakness and “breaking down” of the shoulder. Many times, people with a history of a shoulder dislocation will have continued pain, which may be from instability, or from a different problem, like a rotator cuff tear. Physicians diagnose shoulder instability with a physical examination and history, and with X-rays and imaging studies such as an MR arthrogram—a special MRI that allows evaluation of the labrum and ligaments.

Q: How is shoulder instability treated?

A: The typical first step in the treatment of shoulder instability is a good exercise program under the supervision of a physical therapist. The goal of this exercise program is to strengthen the muscles around the shoulder enough so that they can do the job of the injured ligaments and labrum. In certain situations, timely surgical intervention is the best treatment for these problems. Most shoulder instability surgeries can now be performed arthroscopically (an outpatient surgery performed through two to four ¼ inch incisions about the shoulder). People who have shoulder instability surgery typically recover quite well and enjoy adequate shoulder function.