When Sarasota resident Shirley Darling was a little girl, her mother made her sleep without a pillow to keep her posture arrow straight. "She was always telling me and my brother to sit up," recalls the 80-year-old former nurse.

So when Darling noticed her spine starting to curve about eight years ago, she headed straight for an internist and requested a bone density test. He denied her request and sent her home with a clean bill of health.

"He was a very good doctor," Darling insists. "But he goofed on that one." One month later, a rheumatologist confirmed what Darling suspected, that her poor posture was caused by osteoporosis.

With that news, Darling joined the estimated 10 million Americans over the age of 50 who have the condition, which sucks mass from bones, leaving them so weak and brittle that the simple act of sitting can crush an entire pelvis like soapstone.

Although Darling's bone density test showed that her spine had been painlessly succumbing to compression fractures for years, the news could have been worse. The American Academy of Orthopaedic Surgeons (AAOS) says osteoporosis contributes to about 700,000 spine fractures and about 250,000 wrist fractures every year. The U.S. Department of Health and Human Services (HHS) attributes 1.5 million fractures to weak bones that cost nearly $18 billion in medical care. Hip fractures alone account for nearly 300,000 hospitalizations annually, with individual costs reaching more than $80,000.

Risk factors for osteoporosis include smoking and alcohol abuse, but 80 percent of its victims are women, and race is not a factor. AAOS says as many as 49 percent of Mexican-American women 50 years and older have low bone density. And while only 10 percent of African-Americans over the age of 50 have osteoporosis, between 80 and 95 percent of all fractures in African-American women over the age of 64 are related in some way to osteoporosis.

The reason seems to lie in the amount of estrogen a woman produces. Estrogen is crucial to maintain bone mass, but by the time women reach menopause, estrogen drops to one-tenth the levels of pre-menopausal women. In the five to seven years following menopause, women can lose up to 20 percent of their bone mass.

But men are also at risk. "Bone health is dependent on sex hormones [like estrogen in women and testosterone in men]," says Dr. Suhail Khoury, of the Khoury Institute in Sarasota. Although men continue to produce the testosterone that protects their bones until late in life, by the time they reach their 70s, both men and women are losing bone mass at about the same rate.

Approximately one in eight men will eventually experience an osteoporosis fracture. Women suffer hip fractures nearly three times as often as men, but men are nearly twice as likely to die within a year of having the same type of fracture. "A lot of it has to do with recovery," says Dr. Erik Herman, of Kennedy White Orthopedics in Sarasota. Some 20 percent of all hip fracture patients die within a year of the fracture, and 20 percent will end up in nursing homes.

Herman cites complications from hip surgery, including blood clots and pulmonary embolisms, but he says the main problem is immobility. "You lose a significant amount of strength lying in bed," he says. This leaves patients prone to pneumonia and secondary complications that are more dangerous than the initial fracture.

For years, the first line of defense against osteoporosis was hormone replacement therapy. The National Institutes of Health maintains that replacing estrogen and progestin in older women can reduce the rate of hip and spine fractures by 34 percent by increasing bone density and prevent further bone loss, but not everyone agrees with that assessment.

"Bone density is not directly related to fracture," says Khoury. According to Khoury, who has a Ph.D. in physiology, bone efficiency depends on elasticity and plasticity. "If you hit a dried-up tree limb, it breaks," he explains. "A fresh, green limb will bend, even if it's half the size of the dry limb." Mass, he says, plays a big role in preventing fractures, but not the ultimate role.

Don't rely too much on calcium, either. "Calcium is the [substance] needed to prevent bone loss," says Khoury. "But it will not stop the loss. It will slow it down, by 20 to 30 percent, but the process continues."

Between 1993 and 1998, more than 27,000 healthy, postmenopausal women who enrolled in a government study to determine the effects of HRT on preventing bone fractures and other disease were ordered off their drug regimen early when safety monitors noticed a spike in the rate of breast cancer among participants. The rate of heart attacks, stroke, and blood clots in the lung and legs also increased.