Torn Meniscus

Torn Meniscus-torn knee cartilage not limited to athletes or sports

Edited By Carol C. Teitz, M.D., Professor, UW Orthopaedics & Sports Medicine Carol C. Teitz, M.D.

Last updated: December 31, 2009

Overview

Basics of torn meniscus-torn knee cartilage

The knee is made up of the femur (thigh bone) and the tibia ( leg bone) which are held together by ligaments, and the patella (knee cap) which lies in the Quadriceps muscle in the front of the knee.

Between the femur and the tibia are two pads, one on the medial (inner) side of the knee and one on the lateral (outer) side of the knee. Each of these pads is called a meniscus.

The meniscus is made of fibrocartilage which gives it a rubbery texture. However within the meniscus there are also fibers of collagen that help maintain the shape of the meniscus. The meniscus has blood supply only at its outer attachments. Therefore, about 4/5 of a meniscus has no blood supply and therefore cannot heal a tear.

The meniscus functions to improve the fit between the femur and the tibia, to absorb shock and distribute load in the knee, and to help move lubricating fluid around the knee. The meniscus can tear either from trauma or from degeneration.

Immediate medical attention

A torn meniscus needs immediate attention when it "locks" the knee. A knee is locked when it will neither completely bend or completely straighten because something is caught inside. Locking implies that the torn part of the meniscus has displaced into a part of the knee where it doesn't belong or fit.

Facts and myths

Some people think that only athletes can tear a meniscus. This is not true. Even people who do not consider themselves "athletes" can tear a meniscus. Some menisci (plural) tear during activities of daily living such as getting in and out of a car or squatting. Menisci also tear during participation in recreational activities such as skiing , dancing, or racquetball.
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Torn Meniscus -
The menisci are pads
between the femur
and the tibia
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Torn Meniscus -
Types of Meniscal Tears

Symptoms & Diagnosis

Prognosis

A torn meniscus is certainly not life threatening and once treated, the knee will usually function normally for many years.

A meniscal tear that catches, locks the knee, or produces swelling on a frequent or chronic basis should be removed or repaired before it damages the articular (gliding) cartilage in the knee. A meniscal tear that produces discomfort but does not produce any of the symptoms mentioned above may be less likely to damage the rest of the knee. One may choose to "live" with this type of meniscal tear instead of treating it operatively.

Pain

A torn meniscus usually produces well localized pain in the knee. The pain often is worse during twisting or squatting motions. Unless the torn meniscus has locked the knee, many people with a torn meniscus can walk, stand, sit, and sleep without pain. Other people find that the torn meniscus prevents them from participating comfortably in their usual daily activities.

Curability

Symptoms of a torn meniscus, particularly pain, swelling, catching and locking, can be relieved by surgically removing or repairing the torn piece of meniscus. Meniscal repair is reserved for tears in the part of the meniscus that has blood supply.

A slightly different situation exists in the case of a degenerative meniscal tear associated with osteoarthritis. Osteoarthritis in the knee is frequently associated with small degenerative meniscal tears and vice versa. Imaging studies of patients over age 45 with no symptoms in their knees have found that some people have degenerative meniscal tears that they aren't aware of.

The acute symptoms from a new degenerative meniscal tear (pain and swelling) may resolve over a few months time even though the torn area has not healed or been removed. On the other hand, when mechanical symptoms such as catching or locking are present, these symptoms are less likely to resolve without surgery.

Mobility

A torn meniscus can prevent normal pain-free motion of the knee and therefore can interfere with the patient's ability to climb stairs or get in and out of chairs and cars. Sometimes the pain in the knee causes the brain to shut off the Quadriceps muscle at the knee and leads to a "giving way" sensation.

Daily activities

In addition to causing problems in activities of daily living, a torn meniscus usually interferes with the ability to participate in active sports, particularly when they involve twisting motions.

Incidence

Meniscus tears can occur in all age groups. Traumatic tears are most common in active people from age 10-45. Degenerative tears are most common in people from age 40 upward.

Acquisition

Degenerative meniscal tears are thought to occur as part of the aging process when the collagen fibers within the meniscus start to break down and lend less support to the structure of the menicus. Degenerative tears are usually horizontal in the meniscus producing both an upper and lower segment of meniscus. These segments usually don't move out of place and therefore are less likely to produce mechanical symptoms of catching or locking. Traumatic meniscal tears are usually radial or vertical in the meniscus and are more likely to produce a moveable fragment that can catch in the knee and therefore require surgical treatment.

Lifestyle risk factors

Degenerative meniscal tears are also more common in smokers.

Injury & trauma risk factors

Most traumatic meniscal tears occur as a result of a twisting injury when the knee rotates but the foot stays fixed in position. The meniscus can also tear from extreme bending of the knee. The combination of bend, rotation, and sudden kick that occurs in some forms of martial arts is associated with lateral meniscal tears.

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Torn Meniscus -
Extreme bending
can tear a meniscus

Initial symptoms Initial symptoms of a torn meniscus include well-localized pain and swelling in the knee. The pain is usually either on the inner or outer side of the knee, not around the kneecap. When the patient recalls a specific injury that led to the pain and swelling, the swelling often does not occur until the day after the injury. The swelling is not necessarily in the same area as the pain.

Symptoms

A torn meniscus can also produce catching or locking of the knee. Sometimes the knee is stuck in midrange for days at a time. Sometimes the patient can "unlock" the knee by bending and twisting it before trying to straighten it.

Progression

Over 4-6 weeks, the pain and swelling may decrease and activites of daily living may become tolerable. However, athletic activities may reproduce pain and swelling. Sometimes even activities of daily living such as going up and down stairs or getting in and out of cars may produce pain in a knee with a torn meniscus.

Secondary effects

A torn meniscus often causes the knee to make extra joint fluid. There is more room in the knee for fluid when the knee is slightly bent. Therefore, people with chronic swelling tend to hold the involved knee in a bent position and develop hamstring tightness and joint contracture. Also, a piece of torn meniscus that is moving in and out of place can damage the nearby articular (gliding) surfaces and lead to arthritis.

Conditions with similar symptoms

Sometimes the symptoms of a torn meniscus can be confused with a fragment of arthritic articular cartilage that is hanging from the surface of the bone or that has broken free in the joint.

Causes

Meniscus tears can occur in all age groups. Traumatic tears are most common in active people from age 10-45. Degenerative tears are most common in people from age 40 upward.

Degenerative meniscal tears are thought to occur as part of the aging process when the collagen fibers within the meniscus start to break down and lend less support to the structure of the menicus. Degenerative tears are usually horizontal in the meniscus producing both an upper and lower segment of meniscus. These segments usually don't move out of place and therefore are less likely to produce mechanical symptoms of catching or locking. Traumatic meniscal tears are usually radial or vertical in the meniscus and are more likely to produce a moveable fragment that can catch in the knee and therefore require surgical treatment.

Degenerative meniscal tears are also more common in smokers.

Most traumatic meniscal tears occur as a result of a twisting injury when the knee rotates but the foot stays fixed in position. The meniscus can also tear from extreme bending of the knee. The combination of bend, rotation, and sudden kick that occurs in some forms of martial arts is associated with lateral meniscal tears.

Effects

A torn meniscus can prevent normal pain-free motion of the knee and therefore can interfere with the patient's ability to climb stairs or get in and out of chairs and cars. Sometimes the pain in the knee causes the brain to shut off the Quadriceps muscle at the knee and leads to a "giving way" sensation.

In addition to causing problems in activities of daily living, a torn meniscus usually interferes with the ability to participate in active sports, particularly when they involve twisting motions.

Treatments

Diagnosis

A torn meniscus can often be diagnosed by a physical exam of the knee. The doctor will look for swelling, tenderness on the joint line, loss of motion, and pain with special twisting maneuvers.

Diagnostic tests

An MRI can be used to confirm the diagnosis of a torn meniscus.

Health care team

Orthopedic Surgeons and Sports-Medicine trained primary care doctors are specially trained in the diagnosis of torn meniscus.

Finding a doctor

Doctors specializing in torn meniscus can be located through university medical schools, county medical societies, or state orthopedic societies. Other resources include the American Academy of Orthopedic Surgeons and the American Orthopedic Society for Sports Medicine.
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Torn Meniscus -
The McMurray Maneuver
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Torn Meniscus -
A meniscal tear as seen on MRI

Treatment

When a torn meniscus is diagnosed but the knee is not locked and the patient cannot identify a specific incident associated with the onset of pain, the pain can be treated initially with over the counter pain medications such as acetaminophen or ibuprofen. The patient should avoid pivoting and squatting and should work on keeping Quadriceps muscles strong. If the swelling and pain have not resolved in 6 weeks , they usually won't without surgical intervention.

A traumatically torn meniscus usually requires arthroscopic surgical treatment.

This minimally invasive surgical treatment involves either removing or repairing the torn segment of meniscus using an arthroscope.

Because only the outer 1/4-1/5 of the meniscus has blood supply, repairs are successful when the tear occurs in this vascular region of the meniscus. Tears in the non-vascular region are unlikely to heal and therefore are removed. In the case of a degenerative meniscal tear associated with osteoarthritis, the expected outcome after surgery is different. Although arthroscopically treating the torn meniscus and simultaneously trimming away any shaggy articular cartilage caused by the arthritis may eliminate mechanical symptoms such as catching or locking, the non-mechanical symptoms of osteoarthritis ( stiffness, achiness, weather-related pain) may persist. Therefore, in the setting of a degenerative meniscal tear with osteoarthritis, the patient and doctor also need to discuss treatment alternatives for the arthritis such as injections into the knee or partial or total knee replacement.

Self-management

Avoiding twisting activites may decrease the symptoms from a torn meniscus. Additionally, one should do Quadriceps setting exercises with the knee straight or mini-squats,bending only to 15 degrees, to prevent giving way and keep the Quadriceps muscle from atrophying.

Health care team

As mentioned above, some primary care doctors, arthritis doctors, or rehabilitation medicine doctors can often make the diagnosis. A fellowship trained orthopedic surgeon who regularly does arthroscopic knee surgery is best equipped to treat this problem.

Exercise and therapy

Most meniscal tears cannot heal because of their limited blood supply. Nevertheless, Quadriceps muscle strengthening exercises can help prevent some of the secondary effects of a torn meniscus such as knee cap pain or the sense of buckling.

Medications

Medications such as acetaminophen, aspirin, or ibuprofen may relieve some of the pain, but will not actually treat the underlying meniscal tear. Anti-inflammatory drugs such as ibuprofen or naproxyn may also decrease the associated swelling.

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Torn Meniscus -
A tear in the non-vascular region
of the meniscus as seen
through the arthroscope
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Torn Meniscus -
A probe is inserted in the tear,
immediately adjacent
to the meniscal blood supply

Not all surgical cases are the same, this is only an example to be used for patient education.


Surgery

Surgery is the definitive treatment for torn meniscus. The surgery is done arthroscopically and will include either removal or repair of the torn part of meniscus. Repair can be done only when the tear lies in or just adjacent to the vascular zone of the meniscus.

Joint aspiration

Removal of excess joint fluid can temporarily bring some relief from pain, but the meniscus will not heal and the fluid will usually reaccumulate.

Splints or braces

Braces may provide an increased sense of security but do not treat the meniscus per se.

Strategies for coping

Until the tear can be treated arthroscopically, patients with a torn meniscus can use non-narcotic pain relievers, and should try to do quadriceps muscle contractions to prevent atrophy that is associated with knee pain and swelling.One may also need to modify activities to avoid those that twist the knee.

Adaptive aids

Wearing an ace bandage, a knee sleeve, or brace may make the knee feel more secure.

Resources

More information about torn meniscus may be found at the web site of the American Society for Sports Medicine.

Surgical research

Current research on the treatment of torn meniscus centers around the best method for repair of a torn meniscus and placement of a substitute meniscus when a total meniscal removal has been done previously.

Summary of torn meniscus-torn knee cartilage

Meniscal tears occur from trauma or degeneration or a combination of the two.

Meniscal tears can produce knee pain, swelling, catching, and locking.

Most meniscal tears do not heal because they are in an anatomic area that has no blood supply.

The definitive treatment for meniscal tears is arthroscopic surgery.


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