Don't Knock Your Knees
Women's knees are more susceptible to injury than men's—but there's plenty women can do to stay active and pain-free
By Kathleen Christensen
We women are built to have babies. This is useful for propagating the human species, of course, but it's not so good for women's knees. Our wide hips—and perhaps our hormones—make our knees more vulnerable to injury than men's. But that doesn't mean we need to abandon our active lifestyles. As researchers explore the idiosyncrasies of the female knee, they're uncovering a wide range of ways women can care for their knees to prevent pain and injury and continue to pursue the sports and activities we love.
Identify The Problem
Not every knee ailment afflicts women more than men. However, the three that do are common: kneecap pain, osteoarthritis, and anterior cruciate ligament (ACL) tears. The activities you engage in and your age can influence which of these injuries you might be prone to.
You don't have to be an athlete to develop kneecap pain, technically known as patellofemoral pain syndrome, although women who are runners or who do step aerobics seem to be particularly at risk. (In fact, one variant of the condition is called runner's knee.) Pain typically occurs in the front of the knees, underneath or just below the kneecaps, especially when you descend a hill or stairs or after you sit for a period of time.
"Women have a wider pelvis, and that means that the angle from the hip to the knees is greater in women than it is in men," says Lisa Callahan, MD, medical director of the Women's Sports Medicine Center at the Hospital for Special Surgery in New York and author of The Fitness Factor (Lyons Press, 2002). The theory is that this greater angling of the thighbone to the knee and the lower leg predisposes the kneecap to greater stress and therefore greater risk for pain.
As you reach middle age, osteoarthritis of the knee becomes another common knee ailment. This entails wear and tear of the cartilage, with symptoms that include pain, swelling, and stiffness. "We don't really know why women get more osteoarthritis than men do," says Callahan, although researchers suspect everything from female hormones, which may weaken knee tissue, to high heels, which can add extra strain to the knee joint.
Women who ski or play a sport that involves jumping or quick changes of direction—soccer, basketball, volleyball, or tennis—are particularly prone to tearing their ACL. In fact, you're two to eight times more likely to tear your ACL than a typical man who plays these sports. This is a serious injury: You hear a pop, fall to the ground in pain, and instantly become a candidate for surgery.
Women who play a sport with quick changes of direction are two to eight times more likely to tear their ACL than men who play these sports. Theories abound about why ACL tears are more common in girls and women, rather than in men. Researchers have implicated those wide hips again, as well as other skeletal differences. For example, the femoral notch, the space at the bottom of the thighbone through which the ACL passes, is smaller in women than in men, making for a tighter fit. This cramped space may cause a "shearing" effect or a wearing away of the ACL, which ultimately leads to tears.
Controversy remains over whether female hormones—perhaps estrogen and relaxin, which relax ligaments during pregnancy and childbirth—might make the female ACL more likely to tear. Women who are not pregnant have lesser amounts of these hormones, with levels varying during the course of a menstrual cycle. Scientists have found that women are more likely to tear the ACL during ovulation than at other times. But not everyone is convinced. "If the issue were hormones," says Callahan, "we'd be tearing all of our ligaments a lot more often than men."
Look At Your Lifestyle
We can't change the angle of our thighs or the size of our femoral notches. But we can still do plenty to keep our knees healthy. Callahan starts with a bit of fashion advice: Minimize how often you wear high heels—even wide high heels—which increase the pressure on the knee joint and the ACL. Researchers at the Department of Physical Medicine and Rehabilitation at Harvard Medical School found that wearing high heels caused an average 23 percent increase in knee pressure (Lancet, 1998, vol. 351, no. 9113). So be cautious about how often—and for how long—you wear your favorite heels. "If you're doing a presentation in the morning and you're going to wear a 2-inch pair of heels," says Callahan, "have a lower pair of heels or flats under your desk and switch into them for the afternoon."
Something as simple as how you sit can also make a difference. The traditionally feminine way to do it—with knees crossed—can add additional weight and stress to your knees. Being overweight can also put extra pressure on your knee joints, causing cartilage to break down more quickly. "I hate to say this," says Callahan, "because women are always being told to lose weight. But if you're carrying five extra pounds, it makes a difference to your knees. If you're carrying ten extra pounds, it makes an even bigger difference to your knees." One more reason to keep exercising and eating right.
Work Out Wisely
If you suffer from knee pain, you may think exercise is one of the worst things you can do to get healthy again. But research shows that moderate exercise actually helps prevent knee pain and injury, including the pain of osteoarthritis. One word of caution, though: Don't overdo it. If your knees hurt excessively or if arthritis runs in your family, definitely listen to your legs when they say stop.
Be sure to fit both strength training—weight machines, free weights, exercise bands, and balls—and strengthening exercises such as crunches and push-ups into your workout routine. "Strength training is one of the most important things you can do for your knees," says Callahan, explaining that strong muscles help support the knee joint. Women's hamstrings are often weaker than men's in relation to the quadriceps, creating an imbalance, so be sure to include exercises for hamstrings in your workout, as well as for quads and hips. And don't forget about stretching, such as a regular yoga routine. There's no one-size-fits-all exercise approach, Callahan notes, but a class, personal trainer, video, or book can help you get started in the right direction.
If you're interested in an alternative to surgery, consider a physiatrist. Educate yourself, too, about the sports you participate in. If you run, for example, make sure that you have the right shoes, ensuring that they're comfortable, fit right, and won't increase your chances of getting a twisted knee. You should also increase your mileage gradually—no more than 10 percent to 15 percent per week—so as not to put too much stress on the knees too quickly. If you ski, learn more about bindings to make sure they release properly, and do some knee-specific preseason conditioning. If your favorite activity continues to cause undue stress on your knees, consider the many knee-friendly sports alternatives (see "Time to Go Low Impact?").
For soccer, basketball, and volleyball players, it may be time to relearn a real basic: how to jump. Perhaps because women lack early sports training, they tend to land straight-legged, whereas men generally land with knees bent in a squat position, with less impact and a lesser chance of twisting their knees. When it comes to pivoting or moving sideways, women tend to bring their weight down on one leg in one single step, rather than making the maneuver in a few steps, which minimizes the initial force. "If you can train women to move more like men when it comes to landing," says Callahan, "you might be able to reduce their risk of ACL injury." If your coach isn't knowledgeable about jump training, you can order an instructive video at www.sportsmetrics.net.
If you do develop knee pain that you believe needs medical attention, think carefully about what type of practitioner to consult. Most people assume they should see an orthopedist, says Callahan, "but orthopedists are surgeons, so some of them are going to be inclined to recommend a surgical solution." If you're interested in alternatives, Callahan suggests that you consider a physiatrist—a physician specializing in physical medicine and rehabilitation—or a primary-care physician trained in sports medicine.
Those with osteoarthritis should also be on the lookout for the results of two large ongoing knee osteoarthritis research projects, one on the benefits of acupuncture (results are due out next year), the other on the effects of the supplements glucosamine and chondroitin sulfate (results due in 2005). Log on to MEDLINEplus (www.medlineplus.gov) for the latest research. Several smaller studies already suggest that acupuncture may help relieve the pain of both osteoarthritis and patellofemoral syndrome. And according to Callahan, "glucosamine, chondroitin, and the amino acid S-adenosyl methionine (SAM-e) can all be helpful in managing knee pain, particularly with mild to moderate osteoarthritis of the knee."
To keep yourself healthy, respect your female anatomy, but don't baby your knees. Learn, strengthen, stretch—and keep moving./p> Freelance writer Kathleen Christensen suffered from runner's knee when she was younger. She now does yoga to keep knee pain at bay.