Health Topics
Publication Date: May 2001
Questions and Answers About Knee Problems
Knee problems commonly occur in young people and adults.
This booklet contains general information about several knee problems.
It includes descriptions and a diagram of the different parts of the
knee. Individual sections of the booklet describe the symptoms, diagnosis,
and treatment of specific types of knee injuries and conditions. Information
on how to prevent these problems is also provided.
What Do the Knees Do? How Do They Work?
The knees provide stable support for the body and allow
the legs to bend and straighten. Both flexibility and stability are
needed for standing and for motions like walking, running, crouching,
jumping, and turning.
Several kinds of supporting and moving parts, including
bones, cartilage, muscles, ligaments, and tendons, help the knees do
their job. Any of these parts can be involved in pain or dysfunction.
What Causes Knee Problems?
There are two general kinds of knee problems: mechanical
and inflammatory.
Mechanical Knee Problems
Some knee problems result from injury, such as a direct
blow or sudden movements that strain the knee beyond its normal range
of movement. Other problems, such as osteoarthritis in the knee, result
from wear and tear on its parts.
Inflammatory Knee Problems
Inflammation that occurs in certain rheumatic diseases,
such as rheumatoid arthritis and systemic lupus erythematosus, can damage
the knee.
Joint Basics
The point at which two or more bones are connected is called
a joint. In all joints, the bones are kept from grinding against each
other by padding called cartilage. Bones are joined to bones by strong,
elastic bands of tissue called ligaments. Tendons are tough cords of
tissue that connect muscle to bone. Muscles work in opposing pairs to
bend and straighten joints. While muscles are not technically part of
a joint, they're important because strong muscles help support and protect
joints.
What Are the Parts of the Knee?
Like any joint, the knee is composed of bones and cartilage,
ligaments, tendons, and muscles (see the diagram).
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 (knee cap). The patella is 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. One pad is called a meniscus
(muh-NISS-kus). The plural is menisci (muh-NISS-sky). The menisci 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. Keeping these muscles strong with exercises
such as walking up stairs or riding a stationary bicycle helps support
and protect the knee.
Tendons and Ligaments
The quadriceps tendon connects the quadriceps muscle to
the patella and provides the power to extend the leg. Four ligaments
connect the femur and tibia and give the joint strength and stability:
- The medial collateral ligament (MCL) provides stability to the inner
(medial) part of the knee.
- The lateral collateral ligament (LCL) provides stability to the
outer (lateral) part 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.
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 the location of pain. The patient may be
asked to stand, walk, or squat to help the doctor assess the knee's
function.
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 such as ligaments
or muscles more clearly than conventional x rays. The computer can
combine individual images 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 knee tissue to produce signals
that are detected by a scanner and analyzed by a computer. This creates
a series of cross-sectional images of a specific part of the knee.
An MRI is particularly useful for detecting soft tissue damage or
disease. Like a CAT scan, a computer is 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. While the arthroscope is inside
the knee joint, removal of loose pieces of bone or cartilage or the
repair of torn ligaments and menisci is also possible.
- Biopsy--The doctor removes tissue to examine under a microscope.
Knee Injuries and Problems
Arthritis
What Is Arthritis of the Knee?
Arthritis of the knee is most often osteoarthritis. In this
disease, the cartilage in the joint gradually wears away. In rheumatoid
arthritis, which can also affect the knees, the joint becomes inflamed
and cartilage may be destroyed.* Arthritis not only affects joints;
it can also affect supporting structures such as muscles, tendons, and
ligaments.
Osteoarthritis may be caused by excess stress on the joint
from deformity, repeated injury, or excess weight. It most often affects
middle-aged and older people. A young person who develops osteoarthritis
may have an inherited form of the disease or may have experienced continuous
irritation from an unrepaired torn meniscus or other injury. Rheumatoid
arthritis often affects people at an earlier age than osteoarthritis.
* The National Institute of Arthritis and
Musculoskeletal and Skin Diseases Information Clearinghouse has separate
publications on osteoarthritis, rheumatoid arthritis, and knee replacement.
See the end of this booklet for contact information.
Signs and Diagnosis
Someone who has arthritis of the knee may experience pain,
swelling, and a decrease in knee motion. A common symptom is morning
stiffness that lessens as the person moves around. Sometimes the joint
locks or clicks when the knee is bent and straightened, but these signs
may occur in other knee disorders as well. The doctor may confirm the
diagnosis by performing a physical examination and examining x rays,
which typically show a loss of joint space. Blood tests may be helpful
for diagnosing rheumatoid arthritis, but other tests may be needed too.
Analyzing fluid from the knee joint may be helpful in diagnosing some
kinds of arthritis. The doctor may use arthroscopy to directly see damage
to cartilage, tendons, and ligaments and to confirm a diagnosis, but
arthroscopy is usually done only if a repair procedure is to be performed.
Treatment
Most often osteoarthritis of the knee is treated with pain-reducing
medicines, such as aspirin or acetaminophen (Tylenol*); nonsteroidal
anti-inflammatory drugs (NSAIDs), such as ibuprofen (Motrin, Nuprin,
Advil); and exercises to restore joint movement and strengthen the knee.
Losing excess weight can also help people with osteoarthritis.
Rheumatoid arthritis of the knee may require physical therapy
and more powerful medications. In people with arthritis of the knee,
a seriously damaged joint may need to be replaced with an artificial
one. (A new procedure designed to stimulate the growth of cartilage
by using a patient's own cartilage cells is being used experimentally
to repair cartilage injuries at the end of the femur at the knee. It
is not, however, a treatment for arthritis.)
* Brand names included in this booklet are
provided as examples only, and their inclusion does not mean that these
products are endorsed by the National Institutes of Health or any other
Government agency. Also, if a particular brand name is not mentioned,
this does not mean or imply that the product is unsatisfactory.
Cartilage Injuries and Disorders
What Is Chondromalacia?
Chondromalacia (KON-dro-mah-LAY-she-ah), also called chondromalaciapatellae,
refers to softening of the articular cartilage of the knee cap. This
disorder occurs most often in young adults and can be caused by injury,
overuse, parts out of alignment, or muscle weakness. Instead of gliding
smoothly across the lower end of the thigh bone, the knee cap rubs against
it, thereby roughening the cartilage underneath the knee cap. The damage
may range from a slightly abnormal surface of the cartilage to a surface
that has been worn away to the bone. Chondromalacia related to injury
occurs when a blow to the knee cap tears off either a small piece of
cartilage or a large fragment containing a piece of bone (osteochondral
fracture).
Symptoms and Diagnosis
The most frequent symptom is a dull pain around or under
the knee cap that worsens when walking down stairs or hills. A person
may also feel pain when climbing stairs or when the knee bears weight
as it straightens. The disorder is common in runners and is also seen
in skiers, cyclists, and soccer players. A patient's description of
symptoms and a followup x ray usually help the doctor make a diagnosis.
Although arthroscopy can confirm the diagnosis, it's not performed unless
the condition requires extensive treatment.
Treatment
Many doctors recommend that patients with chondromalacia
perform low-impact exercises that strengthen muscles, particularly the
inner part of the quadriceps, without injuring joints. Swimming, riding
a stationary bicycle, and using a cross-country ski machine are acceptable
as long as the knee doesn't bend more than 90 degrees. Electrical stimulation
may also be used to strengthen the muscles. If these treatments don't
improve the condition, the doctor may perform arthroscopic surgery to
smooth the surface of the cartilage and "wash out" the cartilage fragments
that cause the joint to catch during bending and straightening. In more
severe cases, surgery may be necessary to correct the angle of the knee
cap and relieve friction with the cartilage or to reposition parts that
are out of alignment.
Injuries to the Meniscus
What Causes Injuries to the Meniscus?
The meniscus is easily injured by the force of rotating
the knee while bearing weight. A partial or total tear 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.
Symptoms
Generally, when people injure a meniscus, they feel some
pain, particularly when the knee is straightened. If the pain is mild,
the person may continue moving. Severe pain may occur if a fragment
of the meniscus catches between the femur and the 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 makes the knee swell. 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. Although symptoms of meniscal injury may
disappear on their own, they frequently persist or return and require
treatment.
Diagnosis
In addition to listening to the patient's description of
the onset of pain and swelling, the doctor may perform a physical examination
and take x rays of the knee. The examination may include a test in which
the doctor bends the leg, then rotates the leg outward and inward while
extending it. Pain or an audible click suggests a meniscal tear. An
MRI may be recommended to confirm the diagnosis. Occasionally, the doctor
may use arthroscopy to help diagnose and treat a meniscal tear.
Treatment
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 started with guidance from a doctor and
physical therapist or exercise therapist. The therapist will make sure
that the patient does the exercises properly and without risking 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 not straightening it 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 (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 is more extensive, the doctor may perform arthroscopic
or open surgery to see the extent of injury and to repair the tear.
The doctor can sew the meniscus back in place if the patient is relatively
young, if the injury is in an area with a good blood supply, and if
the ligaments are intact. Most young athletes are able to return to
active sports after meniscus 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, osteoarthritis is more likely to develop in the knee if the
meniscus is removed. Medical researchers are investigating a procedure
called an allograft, in which the surgeon replaces the meniscus with
one from a cadaver. A grafted meniscus is fragile and will shrink and
tear easily. Researchers have also attempted to replace a meniscus with
an artificial one, but this procedure is even less successful than an
allograft.
Recovery after surgical repair takes several weeks, and
postoperative 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 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 ACL.
Ligament Injuries
What Are the Causes of Anterior and Posterior Cruciate
Ligament Injuries?
Injury to the cruciate ligaments is sometimes referred to
as a "sprain."* The ACL is most often stretched or torn (or both) by
a sudden twisting motion (for example, when the feet are planted one
way and the knees are turned another).
The PCL is most often injured by a direct impact, such as
in an automobile accident or football tackle.
* The National Institute of Arthritis and
Musculoskeletal and Skin Diseases Information Clearinghouse has a separate
publication on sprains and strains. See the end of this booklet for
contact information.
Symptoms and Diagnosis
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. The doctor may perform several tests to
see whether the parts of the knee stay in proper position when pressure
is applied in different directions. A thorough examination is essential.
An MRI is very accurate in detecting a complete tear, but arthroscopy
may be the only reliable means of detecting a partial one.
Treatment
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 brace to protect the knee during activity.
For a completely torn ACL in an active athlete and motivated person,
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 synthetic ligaments have been tried
in experiments, the results have not been as good as with human tissue.
One of the most important elements in a patient's successful recovery
after cruciate ligament surgery is a 4- to 6-month exercise and rehabilitation
program that may involve using special exercise equipment at a rehabilitation
or sports center. Successful surgery and rehabilitation will allow the
patient to return to a normal lifestyle.
What Is the Most Common Cause of Medial and Lateral Collateral
Ligament Injuries?
The MCL is more easily injured than the LCL. The cause is
most often a blow to the outer side of the knee that stretches and tears
the ligament on the inner side of the knee. Such blows frequently occur
in contact sports like football or hockey.
Symptoms and Diagnosis
When injury to the MCL occurs, a person may feel a pop and
the knee may buckle sideways. Pain and swelling are common. A thorough
examination is needed to determine the kind and extent of the injury.
To diagnose a collateral ligament injury, the doctor exerts pressure
on the side of the knee to determine the degree of pain and the looseness
of the joint. An MRI is helpful in diagnosing injuries to these ligaments.
Treatment
Most sprains of the collateral ligaments will heal if the
patient follows a prescribed exercise program. In addition to exercise,
the doctor may recommend ice packs to reduce pain and swelling and 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 ACL, which usually requires surgical
repair.
Tendon Injuries and Disorders
What Causes 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. Also,
trying to break a fall may cause the quadriceps muscles to contract
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 because in sports that require jumping,
such as basketball, the muscle contraction and force of hitting the
ground after a jump strain the tendon. After repeated stress, the tendon
may become inflamed or tear.
Symptoms and Diagnosis
People with tendinitis often have tenderness at the point
where the patellar tendon meets the bone. In addition, they may feel
pain during 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 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.
Treatment
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. For a partial tear, the doctor
might apply a cast without performing surgery.
Rehabilitating a partial or complete tear of a tendon requires
an exercise program 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
repeat injury. A rehabilitation program may last 6 months, although
the patient can return to many activities before then.
What Causes Osgood-Schlatter Disease?
Osgood-Schlatter disease is caused by repetitive stress
or tension on 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 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.
Symptoms and Diagnosis
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, the motion
of the knee is not affected. Pain may last a few months and may recur
until the child's growth is completed.
Osgood-Schlatter disease is most often diagnosed by the
symptoms. An x ray may be normal, or show an injury, or, more typically,
show that the growth area is in fragments.
Treatment
Usually, the disease resolves without treatment. Applying
ice to the knee when pain 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 moderate or less stressful sports activities may
need to wear knee pads for protection and apply ice to the knee after
activity. If there is a great deal of pain, sports activities may be
limited until discomfort becomes tolerable.
What Causes Iliotibial Band Syndrome?
This is an overuse condition in which inflammation results
when a band of a tendon rubs over the outer bone (lateral condyle) of
the knee. Although iliotibial band syndrome may be caused by direct
injury to the knee, it is most often caused by the stress of long-term
overuse, such as sometimes occurs in sports training.
Symptoms and Diagnosis
A person with this syndrome feels an ache or burning sensation
at the side of the knee during activity. Pain may be localized at the
side of the knee or radiate up the side of the thigh. A person may also
feel a snap when the knee is bent and then straightened. Swelling is
usually absent and knee motion is normal. The diagnosis of this disorder
is typically based on the symptoms, such as pain at the outer bone,
and exclusion of other conditions with similar symptoms.
Treatment
Usually, iliotibial band syndrome disappears if the person
reduces activity and performs stretching exercises followed by muscle-strengthening
exercises. In rare cases when the syndrome doesn't disappear, surgery
may be necessary to split the tendon so it isn't stretched too tightly
over the bone.
Other Knee Injuries
What Is Osteochondritis Dissecans?
Osteochondritis dissecans results from a loss of the blood
supply to an area of bone underneath a joint surface and usually involves
the knee. The affected bone and its covering of cartilage gradually
loosen and cause pain. This problem usually arises spontaneously in
an active adolescent or young adult. It may be due to a slight blockage
of a small artery or to an unrecognized injury or tiny fracture that
damages the overlying cartilage. A person with this condition may eventually
develop osteoarthritis.
Lack of a blood supply can cause bone to break down (avascular
necrosis).* The involvement of several joints or the appearance of osteochondritis
dissecans in several family members may indicate that the disorder is
inherited.
* The National Institute of Arthritis and
Musculoskeletal and Skin Diseases Information Clearinghouse has a separate
publication on avascular necrosis. See the end of this booklet for contact
information.
Symptoms and Diagnosis
If normal healing doesn't occur, cartilage separates from
the diseased bone and a fragment breaks loose into the knee joint, causing
weakness, sharp pain, and locking of the joint. An x ray, MRI, or arthroscopy
can determine the condition of the cartilage and can be used to diagnose
osteochondritis dissecans.
Treatment
If cartilage fragments have not broken loose, a surgeon
may fix them in place with pins or screws that are sunk into the cartilage
to stimulate a new blood supply.
If fragments are loose, the surgeon may scrape down the
cavity to reach fresh bone and add a bone graft and fix the fragments
in position. Fragments that cannot be mended are removed, and the cavity
is drilled or scraped to stimulate new cartilage growth. Research is
being done to assess the use of cartilage cell and other tissue transplants
to treat this disorder.
What Is Plica Syndrome?
Plica (PLI-kah) syndrome occurs when plicae (bands of synovial
tissue) are irritated by overuse or injury. Synovial plicae are the
remains of tissue pouches found in the early stages of fetal development.
As the fetus develops, these pouches normally combine to
form one large synovial cavity. If this process is incomplete, plicae
remain as four folds or bands of synovial tissue within the knee. Injury,
chronic overuse, or inflammatory conditions are associated with this
syndrome.
Symptoms and Diagnosis
People with this syndrome are likely to experience pain
and swelling, a clicking sensation, and locking and weakness of the
knee. Because the symptoms are similar to those of some other knee problems,
plica syndrome is often misdiagnosed. Diagnosis usually depends on excluding
other conditions that cause similar symptoms.
Treatment
The goal of treatment is to reduce inflammation of the synovium
and thickening of the plicae. The doctor usually prescribes medicine
such as ibuprofen to reduce inflammation. The patient is also advised
to reduce activity, apply ice and an elastic bandage to the knee, and
do strengthening exercises. A cortisone injection into the plica folds
helps about half of those treated. If treatment fails to relieve symptoms
within 3 months, the doctor may recommend arthroscopic or open surgery
to remove the plicae.
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
such as 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).
How Can People Prevent Knee Problems?
Some knee problems, such as those resulting from an accident,
can't be foreseen or prevented. However, a person can prevent many knee
problems by following these suggestions:
- Before exercising or participating in sports, warm up by walking
or riding a stationary bicycle, then do stretches. 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 way to strengthen the
leg muscles that support 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
can be caused by flat feet or overpronated feet (feet that roll inward).
People can often reduce some of these problems by wearing special
shoe inserts (orthotics). Maintain a healthy weight to reduce stress
on the knee. Obesity increases the risk of degenerative (wearing)
conditions such as osteoarthritis of the knee.
What Types of Exercise Are Most Suitable
for Someone With Knee Problems?
Three types of exercise are best for people with arthritis:
- Range-of-motion exercises help maintain normal joint movement
and relieve stiffness. This type of exercise helps maintain or increase
flexibility.
- Strengthening exercises help keep or increase muscle strength.
Strong muscles help support and protect joints affected by arthritis.
- Aerobic or endurance exercises improve function of the heart
and circulation and help control weight. Weight control can be important
to people who have arthritis because extra weight puts pressure on
many joints. Some studies show that aerobic exercise can reduce inflammation
in some joints.
Where Can People Find More Information
About Knee Problems?
National Institute of Arthritis and Musculoskeletal and
Skin
Diseases Information Clearinghouse
National Institutes of Health
1 AMS Circle
Bethesda, MD 20892-3675
Phone: 301-495-4484 or
877-22-NIAMS (226-4267) (free of charge)
TTY: 301-565-2966
Fax: 301-718-6366
http://www.niams.nih.gov/
The clearinghouse provides information about various forms
of arthritis and rheumatic disease and bone, muscle, and skin diseases.
It distributes patient and professional education materials and refers
people to other sources of information. Additional information and updates
can also be found on the NIAMS Web site.
American Academy of Orthopaedic Surgeons
P.O. Box 2058
Des Plaines, IL 60017
Phone: 800-824-BONE (2663) (free of charge)
www.aaos.org
The academy provides education and practice management
services for orthopaedic surgeons and allied health professionals. It
also serves as an advocate for improved patient care and informs the
public about the science of orthopaedics. The orthopaedist's scope of
practice includes disorders of the body's bones, joints, ligaments,
muscles, and tendons. For a single copy of an AAOS brochure, send a
self-addressed stamped envelope to the address above or visit the AAOS
Web site.
American College of Rheumatology
1800 Century Place, Suite 250
Atlanta, GA 30329
Phone: 404-633-3777
Fax: 404-633-1870
www.rheumatology.org
This national professional organization can provide referrals
to rheumatologists and allied health professionals, such as physical
therapists. One-page fact sheets are available on various forms of arthritis.
Lists of specialists by geographic area and fact sheets are also available
on this Web site.
American Physical Therapy Association
1111 N. Fairfax Street
Alexandria, VA 22314
Phone: 800-999-APTA (2782) (free of charge)
www.apta.org
The association publishes a free brochure titled "Taking
Care of the Knees."
Arthritis Foundation
1330 West Peachtree Street
Atlanta, GA 30309
Phone: 404-872-7100 or 800-283-7800 (free of charge)
or call your local chapter (listed in the local telephone directory)
www.arthritis.org
The foundation has several free brochures about coping with
arthritis, taking nonsteroid and steroid medicines, and exercise. A
free brochure on protecting your joints is titled "Using Your Joints
Wisely." The foundation also can provide addresses and phone numbers
for local chapters and physician and clinic referrals.
Acknowledgments
The NIAMS gratefully acknowledges the assistance of Barbara
Mittleman, M.D., and James Panagis, M.D., M.P.H., NIAMS, NIH; John H.
Klippel, M.D., Arthritis Foundation, Atlanta, Georgia; Frank A. Pettrone,
M.D., Arlington/Vienna, Virginia; and W. Norman Scott, M.D., Beth Israel
Medical Center, New York, New York, in the preparation and review of
this booklet.
The mission of the National Institute of Arthritis and Musculoskeletal
and Skin Diseases (NIAMS) is to support research into the causes, treatment,
and prevention of arthritis and musculoskeletal and skin diseases; the
training of basic and clinical scientists to carry out this research;
and the dissemination of information on research progress in these diseases.
The NIAMS Information Clearinghouse is a public service sponsored by
the NIAMS that provides health information and information sources.
Additional information and research updates can be found on the NIAMS
Web site at http://www.niams.nih.gov/.
This booklet is not copyrighted. Readers are encouraged
to duplicate and distribute as many copies as needed.
Additional copies of this booklet are available from
National Institute of Arthritis and Musculoskeletal
and Skin Diseases (NIAMS) Information Clearinghouse
National Institutes of Health (NIH)
1 AMS Circle
Bethesda, MD 20892-3675
NIH Publication No. 01-4912
