Managing Osteoarthritis of the Knee

Weight loss: Lightening the load

Every step you take exposes your knee joints to a force equal to three to five times your body weight. If you have osteoarthritis, a weight gain or loss of just 5 pounds can cause a noticeable difference in the amount of pain you feel. One study of overweight or obese older adults who had knee osteoarthritis found that for every pound of weight they lost, the stress on their knees was reduced fourfold. Obesity not only puts added stress on the knees, it also spurs the production of inflammatory proteins that may hasten cartilage degeneration. Weight loss can help preserve cartilage and reduce symptoms.

"People don't appreciate the strong connection between obesity and osteoarthritis. If you lose 10% of your body weight, you can reduce pain by 50%," says Dr. Patience White, vice president for public health at the Arthritis Foundation. The AAOS recommends that overweight or obese women with knee osteoarthritis reduce their body weight at least 5%.

Anatomy of knee osteoarthritis Age, mechanical wear and tear, genetics, and biochemical factors all contribute to the gradual breakdown of cartilage, a protective tissue that covers the ends of bones. In the knee, the cartilage covering the condyles (the knobs at the lower end of the thighbone) degrades, which can result in the femur and tibia rubbing against each other.

Exercise: Motion as medicine

Lack of exercise and knee osteoarthritis can produce a downward spiral of increasing disability. Lack of exercise makes you more likely to develop knee osteoarthritis; the pain of osteoarthritis makes you avoid exercise; and avoiding exercise makes the arthritis worse. The key to breaking this cycle is exercise.

"People may find it surprising that a painful condition can be improved more by exercise than rest. There's good data that effective measures such as exercise are being underused," says Dr. Jeffrey Katz, professor of medicine and orthopedic surgery at Harvard Medical School and a rheumatologist at Boston's Brigham and Women's Hospital.

Regular light to moderate exercise (during which you sweat lightly but can talk easily) can slow the disease process and reduce your pain. The exercise should be individually tailored to prevent injury, so start with an evaluation by a clinician or physical therapist experienced in managing osteoarthritis. A program to improve knee osteoarthritis may include the following:

Low-impact aerobic exercise. Swim, cycle, walk, or use an elliptical trainer (a machine that simulates walking or stair-climbing without stressing the joints) and gradually increase the time you spend doing it. Also, try to incorporate more activity in your daily tasks—for example, park farther from your destination and walk, or use stairs instead of the elevator.

Quadriceps strengthening. Strengthening the thigh muscles will help protect the knee and improve pain, stiffness, and balance. (For exercises that work the quadriceps, see "Knee-strengthening exercises") If your joints are poorly aligned or the ligaments are overstretched, consult a physical therapist for safe strengthening exercises.

Flexibility. Muscle stiffness can limit knee-joint movement and lead to further pain. Stretching and range-of-motion exercises may help.

Balance. Knee osteoarthritis can interfere with balance by impairing the capacity of receptors in your joints to detect the position of your body in space. You can improve your balance with strengthening exercises as well as specific balance exercises and activities such as tai chi.

For help in starting and maintaining an exercise program, contact your local Arthritis Foundation about their self-help program (www.arthritis.org/programs). A book based on the program is also available (see "Selected resources").

Reduce pain with medications

Medications can't change the course of osteoarthritis, but they can help ease pain and make it possible for you to exercise.

The AAOS suggests using the following medications to control symptoms: acetaminophen (Tylenol), no more than 4 grams per day; nonsteroidal anti-inflammatory drugs (NSAIDs) combined or taken with agents to protect the stomach lining (NSAIDs should also be taken with food); cyclooxygenase-2 (COX-2) inhibitors, such as celecoxib (Celebrex); or topical NSAIDs, such as diclofenac sodium (Voltaren Gel). These recommendations are designed to reduce the risk of gastrointestinal bleeding. Some guidelines also endorse the use of topical capsaicin, a pain-relieving substance found in chili peppers.

If you can't tolerate oral medications or need greater pain relief, your clinician may suggest a corticosteroid injection to reduce inflammation and improve joint function. The effects of a single corticosteroid injection may last for several weeks. (To avoid tissue weakening, corticosteroid injections are given no more often than once every three to four months.)

Another approach is viscosupplementation—injections of hyaluronic acid, a substance found in joint fluid, to provide added lubrication and cushioning in the knee joint. Several formulations of hyaluronic acid are available, approved by the FDA as medical devices rather than drugs. It's unclear how effective these products are in relieving pain or improving function; the AAOS is still reviewing the evidence.

Knee-strengthening exercises Straight-leg raise. Lie on your back, and tighten the thigh muscles of one leg with your knee fully straightened. Lift your leg several inches, and hold for 10 seconds. Lower slowly; repeat until your thigh muscle feels fatigued, then switch to the other leg. Wall sit. Stand with your back against the wall. Bend your knees, and slowly lower yourself into a sitting position. Hold this position for 20 seconds. Stand again, and repeat.

Supportive aids

Depending on the location and severity of your osteoarthritis, you may walk more easily with mechanical support.

There's some evidence that therapeutic knee taping—the application of tape to better align the knee—can help relieve pain. It's not entirely clear how taping brings about pain relief, but it's thought that improved alignment reduces stress on surrounding soft tissues and may help in activating and strengthening the quadriceps muscles. A physical therapist can tape your knee and teach you how to do it yourself.

Although the AAOS endorses the use of tape, it does not recommend for or against the use of knee braces, because research on their effectiveness is limited. Some braces shift the load away from an affected part of the knee, while others support the entire knee. Wedges inserted into the shoes also change the forces acting on the knee, but randomized trials have not shown that this reduces pain or improves function.

Although canes have been used for thousands of years, the first controlled trial of canes for knee osteoarthritis was published just this year. In the two-month trial, cane users, compared with those not using canes, had less pain and better knee function and could walk significantly farther in six minutes (Annals of the Rheumatic Diseases, February 2012). During the first month of the study, walking required more energy for cane users, but they soon adapted to the device. (Canes must be fitted properly and used correctly. To learn more, go to www.health.harvard.edu/womenextra.)

Alternative therapies

Certain alternative treatments may have benefits even though the evidence has not been sufficient for their inclusion in professional guidelines. "A treatment might help you, even if it didn't help enough of the people in the studies that were reviewed," says Dr. White.

Your physician isn't likely to object if you want to give these a try:

Acupuncture. Trials comparing acupuncture with a sham procedure usually find only small short-term reductions in pain, although some individuals get a better response. Over several months, acupuncture plus exercise hasn't been found more effective than exercise alone.

Glucosamine and chondroitin. These popular supplements contain naturally occurring components of cartilage. Despite many studies, it's still not clear whether they can improve pain and knee function. Any benefit may take weeks or months. Dr. Katz suggests that you track your pain levels and function (such as walking ability) and discontinue the supplements after six months if they haven't helped.

Glucosamine and chondroitin are unlikely to do you any harm, but beware of miracle "cures" and other therapies with little or no supporting evidence. Stick with unbiased information sources, such as the Arthritis Foundation and the American Academy of Orthopaedic Surgeons.