I'm
Having Trouble with my Knees!
This
is a very common statement heard in the doctors office, especially
from younger patients involved in sports. Among the most common
sports related injuries are those involving the knee. Below are
some the frequently asked questions by patients with knee problems.
How
Common Are Knee Problems? What Causes Them?
According
to the American Academy of Orthopaedic Surgeons, more than 4.1
million people seek medical care each year for a knee problem.
Some
knee problems result from wear of parts of the knee, such as occurs
in osteoarthritis. Other problems result from injury, such as
a blow to the knee or sudden movements that strain the knee beyond
its normal range of movement.
How
Can People Prevent Knee Problems?
- Some
knee problems, such as those resulting from an accident, cannot
be foreseen or prevented. However, a person can prevent many
knee problems by following these suggestions:
- First
warm up by walking or riding a stationary bicycle, then do stretches
before exercising or participating in sports. Stretching the
muscles in the front of the thigh (quadriceps) and back of the
thigh (hamstrings) reduces tension on the tendons and relieves
pressure on the knee during activity.
- Strengthen
the leg muscles by doing specific exercises (for example, by
walking up stairs or hills, or by riding a stationary bicycle).
A supervised workout with weights is another pathway to strengthening
leg muscles that benefit the knee.
- Avoid
sudden changes in the intensity of exercise. Increase the force
or duration of activity gradually.
- Wear
shoes that both fit properly and are in good condition to help
maintain balance and leg alignment when walking or running.
Knee problems may be caused by flat feet or overpronated feet
(feet that roll inward). People can often reduce some these
problems by wearing special shoe inserts (orthotics). Maintain
appropriate weight to reduce stress on the knee. Obesity increases
the risk of degenerative (wearing) conditions such as osteoarthritis
of the knee.
What
Kinds of Doctors Treat Knee Problems?
Extensive
injuries and diseases of the knees are usually treated by an orthopaedic
surgeon, a doctor who has been trained in the nonsurgical and
surgical treatment of bones, joints, and soft tissues (for example,
ligaments, tendons, and muscles). Patients seeking nonsurgical
treatment of arthritis of the knee may also consult a rheumatologist
(a doctor specializing in the diagnosis and treatment of arthritis
and related disorders).
What
Are the Major Structures of the Knee? What Do They Do?
The
knee joint works like a hinge to bend and straighten the lower
leg. It permits a person to sit, stand, and pivot. The knee is
composed of the following parts (see diagram):
Structures
of the Knee
Bones
and Cartilage
The
knee joint is the junction of three bones—the femur (thigh
bone or upper leg bone), the tibia (shin bone or larger bone of
the lower leg), and the patella (kneecap). The patella is about
2 to 3 inches wide and 3 to 4 inches long. It sits over the other
bones at the front of the knee joint and slides when the leg moves.
It protects the knee and gives leverage to muscles.
The
ends of the three bones in the knee joint are covered with articular
cartilage, a tough, elastic material that helps absorb shock and
allows the knee joint to move smoothly. Separating the bones of
the knee are pads of connective tissue called menisci, which are
divided into two crescent-shaped discs positioned between the
tibia and femur on the outer and inner sides of each knee. The
two menisci in each knee act as shock absorbers, cushioning the
lower part of the leg from the weight of the rest of the body,
as well as enhancing stability.
Muscles
There
are two groups of muscles at the knee. The quadriceps muscle comprises
four muscles on the front of the thigh that work to straighten
the leg from a bent position. The hamstring muscles, which bend
the leg at the knee, run along the back of the thigh from the
hip to just below the knee.
Ligaments
Ligaments
are strong, elastic bands of tissue that connect bone to bone.
They provide strength and stability to the joint. Four ligaments
connect the femur and tibia:
- The
medial collateral ligament (MCL) provides stability to the inner
(medial) aspect of the knee.
- The
lateral collateral ligament (LCL) provides stability to the
outer (lateral) aspect of the knee.
- The
anterior cruciate ligament (ACL), in the center of the knee,
limits rotation and the forward movement of the tibia.
- The
posterior cruciate ligament (PCL), also in the center of the
knee, limits backward movement of the tibia.
Other
ligaments are part of the knee capsule, which is a protective,
fiber-like structure that wraps around the knee joint. Inside
the capsule, the joint is lined with a thin, soft tissue, called
synovium.
Tendons
Tendons
are tough cords of tissue that connect muscle to bone. In the
knee, the quadriceps tendon connects the quadriceps muscle to
the patella and provides power to extend the leg. The patellar
tendon connects the patella to the tibia. Technically, it is a
ligament, but it is commonly called a tendon.
How
Are Knee Problems Diagnosed?
Doctors
use several methods to diagnose knee problems.
- Medical
history—the patient tells the doctor details about symptoms
and about any injury, condition, or general health problem that
might be causing the pain.
- Physical
examination—the doctor bends, straightens, rotates (turns),
or presses on the knee to feel for injury and discover the limits
of movement and location of pain.
- Diagnostic
tests—the doctor uses one or more tests to determine the
nature of a knee problem.
- X
ray (radiography)—an x-ray beam is passed through the knee
to produce a two-dimensional picture of the bones.
- Computerized
axial tomography (CAT) scan—x rays lasting a fraction of
a second are passed through the knee at different angles, detected
by a scanner, and analyzed by a computer. This produces a series
of clear cross-sectional images ( slices”) of the knee
tissues on a computer screen. CAT scan images show soft tissues
more clearly than normal x rays. Individual images can be combined
by computer to give a three-dimensional view of the knee.
- Bone
scan (radionuclide scanning)—a very small amount of radioactive
material is injected into the patient's bloodstream and detected
by a scanner. This test detects blood flow to the bone and cell
activity within the bone, and can show abnormalities in these
processes that may aid diagnosis..
- Magnetic
resonance imaging (MRI)—energy from a powerful magnet (rather
than x rays) stimulates tissues of the knee to produce signals
that are detected by a scanner and analyzed by computer. This
creates a series of cross-sectional images of a specific part
of the knee. An MRI is particularly sensitive for detecting
damage or disease of soft tissues, such as ligaments and muscles.
As with a CAT scan, a computer can be used to produce three-dimensional
views of the knee during MRI.
- Arthroscopy—the
doctor manipulates a small, lighted optic tube (arthroscope)
that has been inserted into the joint through a small incision
in the knee. Images of the inside of the knee joint are projected
onto a television screen.
Knee
Injuries and Problems
Injuries
to the Meniscus
What
Is the Cause of Injuries to the Meniscus?
The
two menisci are easily injured by the force of rotating the knee
while bearing weight. A partial or total tear of a meniscus may
occur when a person quickly twists or rotates the upper leg while
the foot stays still (for example, when dribbling a basketball
around an opponent or turning to hit a tennis ball). If the tear
is tiny, the meniscus stays connected to the front and back of
the knee; if the tear is large, the meniscus may be left hanging
by a thread of cartilage. The seriousness of a tear depends on
its location and extent.
What
Are the Symptoms of Injury?
Generally,
when people injure a meniscus, they feel some pain, particularly
when the knee is straightened. The pain may be mild, and the person
may continue activity. Severe pain may occur if a fragment of
the meniscus catches between the femur and tibia. Swelling may
occur soon after injury if blood vessels are disrupted, or swelling
may occur several hours later if the joint fills with fluid produced
by the joint lining (synovium) as a result of inflammation. If
the synovium is injured, it may become inflamed and produce fluid
to protect itself. This causes swelling of the knee. Sometimes,
an injury that occurred in the past but was not treated becomes
painful months or years later, particularly if the knee is injured
a second time. After any injury the knee may click, lock, or feel
weak. Symptoms of meniscal injury may disappear on their own but
frequently, symptoms persist or return and require treatment.
How
Is Meniscal Injury Diagnosed?
In
addition to listening to the patient's description of the onset
of pain and swelling, the physician may perform a physical examination
and take x rays of the knee. The examination may include a test
in which the doctor flexes (bends) the leg then rotates the leg
outward and inward while extending it. Pain or an audible click
suggests a meniscal tear. An MRI test may be recommended to confirm
the diagnosis. Occasionally, the doctor may use arthroscopy to
help diagnose and treat a meniscal tear.
How
Is an Injured Meniscus Treated?
If
the tear is minor and the pain and other symptoms go away, the
doctor may recommend a muscle-strengthening program. Exercises
for meniscal problems are best performed with initial guidance
from a doctor and physical therapist or exercise therapist. The
therapist will make sure that the patient does the exercises properly
and without risk of new or repeat injury. The following exercises
after injury to the meniscus are designed to build up the quadriceps
and hamstring muscles and increase flexibility and strength.
- Warming
up the joint by riding a stationary bicycle, then straightening
and raising the leg (but avoiding straightening the leg too
much).
- Extending
the leg while sitting (a weight may be worn on the ankle for
this exercise).
- Raising
the leg while lying on the stomach.
- Exercising
in a pool, including walking as fast as possible in chest-deep
water, performing small flutter kicks while holding onto the
side of the pool, and raising each leg to 90 degrees in chest-deep
water while pressing the back against the side of the pool.
If
the tear to a meniscus is more extensive, the doctor may perform
either arthroscopic surgery or open surgery” to see the extent
of injury and to repair the tear. The doctor can suture (sew)
the meniscus back in place if the patient is relatively young,
the injury is in an area with a good blood supply, and the ligaments
are intact. Most young athletes are able to return to vigorous
sports with meniscus-preserving repair.
If
the patient is elderly or the tear is in an area with a poor blood
supply, the doctor may cut off a small portion of the meniscus
to even the surface. In some cases, the doctor removes the entire
meniscus. However, degenerative changes, such as osteoarthritis,
are more likely to develop in the knee if the meniscus is removed.
Medical researchers are currently investigating a procedure called
an allograft, in which the surgeon replaces the meniscus with
one from a cadaver. A grafted meniscus is fragile and may shrink
and tear easily. Researchers have also attempted to replace a
meniscus with an artificial one, but the procedure is even less
successful than an allograft.
Recovery
after surgery to repair a meniscus takes several weeks longer
and post-operative activity is slightly more restricted than when
the meniscus is removed. Nevertheless, putting weight on the joint
actually fosters recovery. Regardless of the form of surgery,
rehabilitation usually includes walking, bending the legs, and
doing exercises that stretch and build up the leg muscles. The
best results of treatment for meniscal injury are obtained in
people who do not show articular cartilage changes and who have
an intact anterior cruciate ligament.
Ligament
Injuries
Anterior
and Posterior Cruciate Ligament Injury
What
Are the Causes of Injury to the Cruciate Ligaments?
Injury
to the cruciate ligaments of the knee is sometimes referred to
as a "sprain." The anterior cruciate ligament is most
often stretched, torn, or both by a sudden twisting motion (for
example, when the feet are planted one way and the knees are turned
another way). The posterior cruciate ligament is most often injured
by a direct impact, such as in an automobile accident or football
tackle.
What
Are the Symptoms of Cruciate Ligament Injury? How Is Injury Diagnosed?
Injury
to a cruciate ligament may not cause pain. Rather, the person
may hear a popping sound, and the leg may buckle when he or she
tries to stand on it. To diagnose an injury, the doctor may perform
several tests to see if the parts of the knee stay in proper position
when pressure is applied in different directions. A thorough examination
is essential to the diagnosis. An MRI is very accurate in detecting
a complete tear, but arthroscopy may be the only reliable means
of detecting a partial tear.
How
Are Cruciate Ligament Tears Treated?
For
an incomplete tear, the doctor may recommend that the patient
begin an exercise program to strengthen surrounding muscles. The
doctor may also prescribe a protective knee brace for the patient
to wear during activity. For a completely torn anterior cruciate
ligament
in
an active athlete and motivated patient, the doctor is likely
to recommend surgery. The surgeon may reattach the torn ends of
the ligament or reconstruct the torn ligament by using a piece
(graft) of healthy ligament from the patient (autograft) or from
a cadaver (allograft). Although repair using synthetic ligaments
has been tried experimentally, the procedure has not yielded as
good results as use of human tissue. One of the most important
elements in a patient's successful recovery after cruciate ligament
surgery is following an exercise and rehabilitation program for
4 to 6 months that may involve the use of special exercise equipment
at a rehabilitation or sports center. Successful surgery and rehabilitation
will allow the patient to return to a normal full lifestyle.
Medial
and Lateral Collateral Ligament Injury
What
Is the Most Common Cause of Injury to the Medial Collateral Ligament?
The
medial collateral ligament is more easily injured than the lateral
collateral ligament. It is most often caused by a blow to the
outer side of the knee, which often happens in contact sports
like football or hockey, that stretches and tears the ligament
on the inner side of the knee.
What
Are the Symptoms of Collateral Ligament Injury? How Is Injury
Diagnosed?
When
injury to the medial collateral ligament occurs, a person may
feel a pop and the knee may buckle sideways. Pain and swelling
are common. A thorough examination is essential to determine the
nature and extent of injury. To diagnose a collateral ligament
injury, the doctor exerts pressure on the side of the knee to
determine the degree of pain and looseness of the joint. An MRI
is helpful in diagnosing injuries to these ligaments.
How
Are Collateral Ligament Injuries Treated?
Most
sprains of the collateral ligaments will heal if the patient follows
a prescribed exercise program. In addition to exercise, the doctor
may recommend that the patient apply ice packs to reduce pain
and swelling and wear a small sleeve-type brace to protect and
stabilize the knee. A sprain may take 2 to 4 weeks to heal. A
severely sprained or torn collateral ligament may be accompanied
by a torn anterior cruciate ligament, which usually requires surgical
repair.
Tendon
Injuries and Disorders
Tendinitis
and Ruptured Tendons
What
Are the Causes of Tendinitis and Ruptured Tendons?
Knee
tendon injuries range from tendinitis (inflammation of a tendon)
to a ruptured (torn) tendon. If a person overuses a tendon during
certain activities such as dancing, cycling, or running, the tendon
stretches like a worn-out rubber band and becomes inflamed. Movements
such as trying to break a fall may cause excessive contraction
of the quadriceps muscles and tear the quadriceps tendon above
the patella or the patellar tendon below the patella. This type
of injury is most likely to happen in older people whose tendons
tend to be weaker. Tendinitis of the patellar tendon is sometimes
called jumper's knee. This is because in sports requiring jumping,
such as basketball, the muscle contraction and force of hitting
the ground after a jump strain the tendon. The tendon may become
inflamed or tear after repeated stress.
What
Are the Symptoms of Tendon Injuries? How Are Injuries Diagnosed?
People
with tendinitis often have tenderness at the point where the patellar
tendon meets the bone. They also may feel pain during faster movements,
such as running, hurried walking, or jumping. A complete rupture
of the quadriceps or patellar tendon is not only painful but also
makes it difficult for a person to bend, extend, or lift the leg
against gravity. If there is not much swelling, the doctor will
be able to feel a defect in the tendon near the tear during a
physical examination. An x ray will show that the patella is lower
in position than normal in a quadriceps tendon tear and higher
than normal in a patellar tendon tear. The doctor may use an MRI
to confirm a partial or total tear.
How
Are Knee Tendon Injuries Treated?
Initially,
the doctor may ask a patient with tendinitis to rest, elevate,
and apply ice to the knee and to take medicines such as aspirin
or ibuprofen to relieve pain and decrease inflammation and swelling.
If the quadriceps or patellar tendon is completely ruptured, a
surgeon will reattach the ends. After surgery, the patient will
wear a cast for 3 to 6 weeks and use crutches. If the tear is
only partial, the doctor might apply a cast without performing
surgery.
A
partial or complete tear of a tendon requires an exercise program
as part of rehabilitation that is similar to but less vigorous
than that prescribed for ligament injuries. The goals of exercise
are to restore the ability to bend and straighten the knee and
to strengthen the leg to prevent a repeat knee injury. A rehabilitation
program may last 6 months, although the patient can return to
many activities before then.
Osgood-Schlatter
Disease
What
Are the Causes of Osgood-Schlatter Disease?
Osgood-Schlatter
disease is caused by repetitive stress or tension on a part of
the growth area of the upper tibia (the apophysis). It is characterized
by inflammation of the patellar tendon and surrounding soft tissues
at the point where the tendon attaches to the tibia. The disease
may also be associated with an avulsion injury, in which the tendon
is stretched so much that it tears away from the tibia and takes
a fragment of bone with it. The disease most commonly affects
active young people, particularly boys between the ages of 10
and 15, who play games or sports that include frequent running
and jumping.
What
Are the Symptoms of Osgood-Schlatter Disease? How Is It Diagnosed?
People
with this disease experience pain just below the knee joint that
usually worsens with activity and is relieved by rest. A bony
bump that is particularly painful when pressed may appear on the
upper edge of the tibia (below the knee cap). Usually, motion
of the knee is not affected. Pain may last a few months and may
recur until a child's growth is completed.
Osgood
Schlatter disease is most often diagnosed by the symptoms. An
x ray may be normal, or show an avulsion injury, or, more typically,
show that the apophysis is in fragments.
How
Is Osgood-Schlatter Disease Treated?
Usually,
the disease disappears without treatment. Applying ice to the
knee when pain first begins helps relieve inflammation and is
sometimes used along with stretching and strengthening exercises.
The doctor may advise the patient to limit participation in vigorous
sports. Children who wish to continue participating in moderate
or less stressful sports may need to wear knee pads for protection
and apply ice to the knee after activity. If a great deal of pain
is felt during sports activities, participation may be limited
until any remaining discomfort is tolerable.
Sources
of Information on Knee Problems
American
Academy of Orthopaedic Surgeons
6300 N. River Road
Rosemont, IL 60018-4262
847/823-7186
800/346-2267
World Wide Web address: http://www.aaos.org
Arthritis
Foundation
1330 Peach Tree Street
Atlanta, GA 30309
404/872-7100
800/283-7800 or call your local chapter (listed in the local telephone
directory)
World Wide Web address: http://www.arthritis.org
National
Arthritis and Musculoskeletal and Skin Diseases Information
Clearinghouse (NAMSIC)
National Institutes of Health
1 AMS Circle
Bethesda, MD 20892-3675
Phone: 301/495-4484
TTY: 301/ 565-2966
Automated faxback system: 301/881-2731
World Wide Web address: http://www.nih.gov/niams
Reference:
in part from National Arthritis and Musculoskeletal and Skin Diseases
Information Clearinghouse
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