There are many treatments short of surgical replacement.
If your knees have become painful, tender, or swollen, are stiff first thing in the morning, or are making crackling noises, the probable cause is osteoarthritis, which affects more than two-thirds of women over age 60. Osteoarthritis results from the breakdown of joint cartilage, the tough, slippery tissue that protects the ends of bones (see "Anatomy of knee osteoarthritis"). Eventually, the cartilage may wear away completely, permitting bone to rub painfully against bone. The goals of osteoarthritis treatment are to reduce pain and stiffness, limit the progression of joint damage, and maintain and improve knee function and mobility.
About 5% of women in the United States over age 50 have had total knee replacement surgery, the recommended treatment when more conservative measures have failed and pain and disability are intolerable. The number of these procedures has more than doubled over the past decade, according to research presented at the 2012 annual meeting of the American Academy of Orthopaedic Surgeons (AAOS). This is partly because knee replacement works—more than 80% of patients say they're satisfied with the results. But experts say it's also a sign that people aren't fully utilizing the many noninvasive strategies that evidence suggests should be tried first—above all, weight loss and exercise.
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").