Body and Brain
Your knee joints are one of the unsung heroes of your body. If you're like the average American, you take just over 5,000 steps a day -- and each one of those steps places a force equal to three to six times your body weight on your knee joints. It's no wonder that by the time you reach age 60, chances are good you will have developed osteoarthritis of the knee, a sometimes-painful condition caused by wear and tear to the knee joint. More than 20 million Americans currently have this condition, and that number is expected to soar as high as 70 million during the next two decades as baby boomers age and become obese, a major risk factor for the disease, increases. While many people with knee osteoarthritis never have symptoms, others experience stiffness and dull pain, especially upon waking, or, in extreme cases, severe pain that limits their mobility.
What is osteoarthritis? In a healthy knee joint, a slippery tissue called cartilage fills the spaces between the bones and cushions the bones as they move. Osteoarthritis (OA) occurs when the cartilage wears away due to daily use -- or overuse. The ends of the bones begin to rub against each other and often develop spurs and cysts. In addition, the tissue that lines the joint may become inflamed and the ligaments and muscles that support the joint weaken.
Most people who develop knee OA are over 45. The disease is more common among women than men, and having osteoporosis or a previous knee injury increases your risk. While genetics plays a role in about 20 to 35 percent of cases, one of the biggest risk factors is something you can control -- your weight. Overweight women (defined as having a body mass index (BMI) of 25-28.9) have a four times greater risk of knee osteoarthritis, and overweight men (BMI 26-29.9) have five times the risk of normal-weight men.
Prevention and relief: There is no cure for osteoarthritis, but there are steps you can take to reduce your chances of developing the disease and to manage the symptoms if you already have it.
1. Control your weight. You can greatly reduce your chances of developing knee OA by maintaining a normal weight or shedding at least some of any excess weight. Losing even a few pounds can make a big difference in the load you place on your knees. Recent studies have found that when overweight people with knee arthritis lost just one pound, it resulted in anywhere from a twofold to fourfold reduction in the load placed on their knee joints. One report estimated that losing 10 pounds would take 48,000 pounds of weight off the knee joint for every mile walked. That, in turn, can reduce wear and tear on the cartilage and prevent osteoarthritis from developing. In fact, losing 11 pounds over a 10-year period decreases the chances of developing osteoarthritis of the knee by 50 percent, according to one recent study. Losing weight can also help reduce knee pain if you already have arthritis.
If you are overweight, talk to your doctor about a healthy weight loss program that includes eating lots of fresh vegetables and fruits, lean protein and whole grains.
2. Exercise. Regular, low-impact exercise will not only help you to lose weight, it can help prevent knee OA and manage symptoms in other ways. Often people who have arthritis of the knee cut back on their physical activity to avoid pain. But that's the worst thing you can do. It's critical to keep the knee joint mobile and flexible and to strengthen the muscles around it. You can do that by combining aerobic exercise with strengthening and flexibility exercises.
Aim for at least 30 minutes of low-impact aerobic exercise five days a week. Walking, biking and golfing are all good choices because they don't place stress on your knee joints. Exercising in water is also a great way to work out because the water supports your weight and gives your knees a break. Studies show that water exercise such as swimming or water aerobics can be especially helpful in reducing pain and improving function in those who already have knee OA.
Exercises that strengthen the muscles around the knee and the quadriceps (thigh) muscle can help protect your knee joints and may actually help prevent osteoarthritis. These exercises can also reduce pain and improve your mobility if you have arthritis. Try isometric exercises where you push or pull against resistance. Stretching exercises like yoga and tai chi can prevent and reduce stiffness in your knee joints.
Talk to your doctor before starting an exercise program -- especially if you have pain in your knees. You may need to begin by working with a physical therapist to learn how to strengthen the muscles around your knees in a safe way.
3. Protect your joints. An injury to your knee can alter the alignment in the joint and that can make the cartilage wear away. So take precautions to avoid injuries to your knees if possible, especially if you do a lot of sports. If you do injure your knee, get immediate treatment to reduce your risk of damaging the cartilage. Wearing a knee brace may help support your knee and reduce pain if you already have arthritis.
4. Pain relievers. Aspirin and other non-prescription pain relievers such as acetaminophen, ibuprofen and naproxen can reduce arthritis pain, but regular use can produce serious side effects. Talk to your doctor about the safe use of these pain relievers.
5. Other treatments. Glucosamine and chondroitin are two natural substances that are found in cartilage. Researchers have been studying whether or not they help relieve arthritis pain when taken as a dietary supplement. Recent studies suggest that they don't help any more than a placebo, but some doctors suggest taking them for three months to see if there is any benefit.
Some doctors prescribe anti-inflammatory gel to relieve pain or injections of hyaluronic acid to lubricate the joint and act like a shock absorber. In very severe cases where other treatments do not provide relief, your doctor may recommend surgery to replace the knee joint.
The best treatment of all is prevention, of course, and the best way to prevent osteoarthritis is to keep your weight down and get in the habit of regular exercise. If you do develop osteoarthritis, an early diagnosis can mean a better outcome -- so see your doctor right away if you notice pain or swelling in your knee.