Think again. If you are within even shouting distance of middle age,
chances are you have osteoarthritis, a degenerative disorder in which
the cartilage—the natural shock absorber that cushions the insides
of your joints—begins to break down. Doctors used to think of it as
a disease of old age, but they now believe that this form of arthritis,
the most common of about 100 types, begins its relentless, initially
painless course when you're still in your 30s, 20s or even younger. Most
of the time you won't suspect anything is wrong until you're in your 40s
or 50s and begin to feel those telltale twinges, signs that the disorder
may be starting to affect your bones. By then the damage has been done,
and even the best treatments can't do much more than ease the pain and
try to maintain the status quo in what are already degenerating joints.
In the U.S., estimates show there are 20 million people with arthritis, a number projected to grow to 40 million by 2020. Getting a statistical measure across Asia is more difficult. And other, more deadly diseases tend to grab more attention. But when you consider the estimates that do exist for Asia's arthritis victims—150 million in India, at least 65 million in China, 10 million in Japan, 1.6 million in Taiwan—along with unanimous testimony from doctors that the number of arthritic patients is rising significantly, it creates a picture that, for Asia's nations and health-care budgets, looks a lot like arthritis itself: painful in the short term, potentially crippling down the line.
What's more, many would-be patients don't know that something can or needs to be done, or they don't have enough information to make an informed (and safe) decision about their care. "Arthritis is a huge problem in our society," says Dr. Koh Wei Howe, president of Singapore's Rheumatoid Arthritis Society. "There are many sufferers out there who are not aware of the available treatments. Some don't even recognize that they have arthritis."
There exists, however, the possibility of some relief amid all the aches and pains. Researchers are paying a lot more attention to osteoarthritis these days. They have discovered that what they thought was a fairly straightforward mechanical breakdown of the joints is a much more complicated process with lots of component parts. Although this means that patients hoping for a quick fix are likely to be disappointed, scientists are starting to gain the kind of insights that can lead to more effective treatments and better strategies for heading off trouble before it begins.
How complex a process are we talking about? Doctors used to think that cartilage was the beginning, middle and end of the osteoarthritis story. Now they know that cartilage is important, but so is everything that surrounds it—muscles, bones, tendons and ligaments. The damage caused by wearing ill-fitting shoes, suffering a football injury or spending day after day stooped over in a field can certainly give rise to arthritic joints. But the worst problems often stem from basic differences in the body's biochemical makeup. For example, some people's cartilage seems to resist damage better than others'. In addition, researchers have discovered an array of biochemical messages that are traded between bones, muscles and other parts of the body and play a key role in keeping joints healthy. "Ultimately, we think it's the biochemical approach that's going to solve the riddle of arthritis," says Dr. Mitchell Sheinkop, an orthopedic surgeon at the Rush—Presbyterian—St. Luke's Medical Center in Chicago. "Someday you may pop a pill and your cartilage will continue to grow, but that's 10 years away—at least."
Until then, what doctors would like to have is some kind of test that will identify people in the earliest stages of osteoarthritis before too much damage has occurred. That way their treatments might stand a better chance of arresting the degenerative process before disability sets in. Unfortunately, conventional X rays, which give very detailed pictures of bone, don't provide very good images of cartilage. And researchers haven't yet discovered any biological markers in the blood that reliably tell them, "Hey, this person's cartilage is starting to fall apart. Do something!"
To understand the latest insights and where they might be leading, it helps to know a little bit about how a joint is put together, and there's no better place to start than with the cartilage. Like so many tissues in the body, cartilage is composed mostly of water. Indeed, you can think of it as a damp sponge. The spongy part contains several important components, including the chondrocytes—cells that generate new bits of cartilage—and various molecules that give the "sponge" its structure and help hold it together.
With every step we take, our moving body puts pressure roughly equal to three times our weight on the knees and hips. As that pressure is distributed across those joints, cartilage is compressed, absorbing most of the load. And, as you might expect with something that resembles a damp sponge, water is squeezed out of the cartilage into the space between the bones. Once the pressure is released, the water flows back into the cartilage, carrying with it nutrients that were picked up from the synovial fluid, which fills the joint. This constant fluid exchange is critical to maintaining healthy, pliable cartilage and explains why joint-moving exercises—such as walking—help delay the progress of osteoarthritis.
Sometime between ages 40 and 55, the activity of the chondrocytes starts slowing down and the cartilage takes longer and longer to replenish itself. As the cushion of cartilage grows progressively thinner, the bones begin to grind against one another. This is a normal consequence of aging, but aging isn't the only culprit. Something as simple as falling on an icy sidewalk or putting on some extra weight can increase your risk of osteoarthritis. Anything that puts extra stress onto the joints will wear out the cartilage that much faster.