Features August 2006 Issue

The Tender Gender

A new understanding of the role gender plays in musculoskeletal problems is causing experts to rethink treatment options.

Men and women are different in more ways than you might think. When the issue is musculoskeletal health, more women than men are prone to problems such as osteoporosis, osteoarthritis, and fractures. Further, gender plays a significant role in how musculoskeletal problems are treated.

Until recently, a woman’s generally smaller size was thought to be the reason for health differences between genders. Researchers now know that gender-specific characteristics have their origins in the cells and are due to the expression of X and Y chromosomes, as well as hormones.

“Your sex chromosomes are reflected in all tissues of the body, so we need to recognize these differences,” says Susan M. Joy, M.D., director of Women’s Sports Health at The Cleveland Clinic. “Future treatments need to be designed to more effectively address these differences.”

Understanding how gender affects anatomy can help you prevent or manage musculoskeletal problems—the number one reason for medical visits in the U.S.—and help you choose a physician who takes gender into account during diagnosis and treatment.

Thinning bones
Osteoporosis—a disease that causes loss of bone mass and destruction of bone tissue, making a bone more susceptible to fracture—illustrates how gender affects disease. Today, 28 million people in the U.S. suffer from osteoporosis, 80 percent of whom are women. Half of all women and one out of every eight men over the age of 50 will experience an osteoporosis-related fracture.

Because of the gender-specific behavior of cells and genes, according to experts at the American Academy of Orthopaedic Surgeons, girls stop growing earlier than boys. As a result, an adult female’s bones are smaller and narrower than a male’s. Female bones gain width until age 14, while male bones widen until age 20, making male bones less apt to fracture.

“Testosterone, the principal male sex hormone, exerts a much more powerful effect on bone and facilitates calcium deposition,” Dr. Joy adds. “Estrogen, the primary female sex hormone, does not have as profound an effect on bone, thereby making women more susceptible to bone-density loss and potential fractures.

“Postmenopausal women lose bone rapidly as a result of their loss of estrogen. This affects not only their bone density, but their bone quality, increasing the risk of fracture. Microfractures and recurrent fractures are more common in women with hormonal alterations or low estrogen levels.”

Bone-density tests are commonly used to diagnose osteoporosis by measuring bone for mineral content; the higher the mineral content, the denser and stronger your bones. While bone density is an important measure, Dr. Joy explains, new techniques are needed to better define bone quality—the structure and architecture of the bone—to help find those at greatest risk of fracture.  

Exercise is key
To prevent osteoporosis, make weight-bearing exercise, such as walking, a regular routine. You also should consume 1,300-1,500 units of calcium daily and 400-800 daily units of vitamin D. “Calcium is best absorbed from foods, such as fortified orange juice, soy milk, and dairy products. It is harder for your body to absorb calcium from supplements, though you should be taking them if your dietary intake is too low,” Dr. Joy notes. “Just drinking three eight-ounce glasses of milk a day will give you 900mg of calcium. In the morning, try switching from coffee to latte.”

Worn joints
Of 21 million Americans diagnosed with osteoarthritis, 16 million are women. In men, osteoarthritis is often caused by sports-related injuries that accelerate the breakdown of cartilage.

“Three factors likely contribute to gender differences that may lead to osteoarthritis—genetics, history of injury, and loading, which refers to the way that muscles perform tasks,” says Dr. Joy. “It is still unclear why women have a greater risk of developing osteoarthritis than men. There are likely multiple factors that contribute to this risk, and further research needs to be done.”

Halt weight gain
The most important factor in preventing and managing arthritis is preventing weight gain. “There’s a tendency to gain weight in middle age and beyond,” says Dr. Joy. “The average person can gain one to two pounds a year after age 30. You can counteract this tendency by controlling caloric intake and exercising. In doing so, you’ll reduce stress on your joints, particularly the knees and hips.” When you walk, each excess pound adds four or more pounds of pressure to your knee; when climbing stairs, each additional pound acts like up to 20 extra pounds on your knees.

Knee injuries
Women are at greater risk of injuring their anterior cruciate ligament (ACL), a fibrous band of tissue that runs deep within the knee joint and helps to keep the joint stable. Muscles and ligaments help support your knee under stress, but ligaments are sometimes looser in a woman’s body, which might make them more susceptible to injury. The female pelvis is also often wider than the male’s, causing a woman’s thighs to angle inward and put additional pressure on her knees.

Compounding the problem is the fact that a woman’s ACL runs through a notch in the thigh that is 20 percent narrower than a male’s. Additionally, a woman’s hamstring muscles tend to be weaker than her quadriceps, creating an imbalance that puts added stress on her knees during certain movements, such as jumping, landing, and rapid direction change.

“You can protect your joints with exercises that involve strengthening the muscles around your joints,” says Dr. Joy. “Resistance training, such as leg presses or wall sits are some good exercises to help you achieve this strength. The stronger your muscles, the less force you put on your joints.” You also can build strong legs with step aerobics, or by exercising on a stair-stepping machine or elliptical trainer.

Frozen shoulder
After age 40, women are more prone than men to “frozen shoulder,” or adhesive capsulitis. The joint thickens and tightens, causing pain, stiffness, and loss of motion. Frozen shoulder occurs more often in people with diabetes and can arise after a shoulder injury. The condition usually improves on its own, though it can take a few years. Meanwhile, anti-inflammatory medication can relieve pain, and shoulder-strengthening exercises can help restore mobility.

Feeling the pain
Women may feel pain differently than men do. Women may also seek help for their pain earlier than a man might. It is believed that different pathways in the brain, as well as hormones, play a role. The difference in perception of pain begins early—research shows that male and female infants respond differently to pain just hours after birth.

Chronic pain conditions—including osteoarthritis, fibromyalgia, and temporomandibular joint disorder (inflammation of the joint that connects the lower jaw to the skull)—affect more women than men, though the reason is unclear.

Which pain medication is effective may also depend on your gender. Evidence of differences in the neural processing of both pain and analgesia is growing. Research shows, for example, that ibuprofen works better in men, while kappa opioids may work better in women. Further research is needed to determine which pain medications might benefit which populations the most.

“The levels of sex hormones decline in aging adults,” says Dr. Joy, “so we need to investigate  the differences that occur and determine more accurately how we can treat the aging population.”