TUESDAY, Jan. 23 (HealthDay News) -- Older women are generally more likely than men to fracture a bone, but once a man has suffered at least one such injury that gender gap disappears, new research shows.

"After a first fracture, the risk of a subsequent fracture in women is doubled, but for men, it is increased three- to four-fold, so that the absolute risk of a subsequent fracture is the same for women and men," said the study's lead author, Jacqueline Center, a senior research officer at the Garvan Institute of Medical Research in Sydney, Australia.

"In other words, the protective effect of being a man on fracture risk was lost after the first fracture," she said.

Center added that the increased risk of refracture lasted as long as 10 years after the initial fracture.

Results of the study are published in the Jan. 24/31 issue of the Journal of the American Medical Association.

According to the American Academy of Orthopaedic Surgeons, fractures are most often caused by serious trauma. But Center said that with fractures that are caused by lower-level trauma -- such as falling from your standing height or less -- osteoporosis may be to blame.

For this study, the Sydney team looked at data on 905 women and 337 Australian men who had suffered a low-level trauma fracture. The study participants were part of a larger, ongoing prospective trial called the Dubbo Osteoporosis Epidemiology Study.

The study began in 1989 and includes about 4,000 men and women over the age of 60. The current analysis included data through 2005.

During the first 10 years following an initial fracture, as many as 60 percent of those included in the study experienced a second fracture.

For women, the risk of a second fracture was 95 percent higher than for an initial fracture. For men, the risk for second fracture was 3.5 times higher than experiencing a first fracture.

Women's absolute refracture risk after one fracture was the same as or greater than a woman who was 10 years older but who had never experienced fracture, the researchers say. For men, the refracture rate was similar to that of a man 20 years older.

That means a 60-year-old man who fractures a bone now has the same risk of receiving another fracture as an 80-year-old man, according to the study.

Lower bone density, older age and a history of smoking all increased the risk of subsequent fractures for women, while low bone density, less physical activity and lower calcium intake were associated with the risk of refracture in men.

"The most important thing people need to know is that after virtually any first low-trauma fracture, the risk of subsequent fracture is increased substantially. For men, this increased risk brings them to a level equal to women, so that the protective effect of being a man disappears altogether," said Center.

"After a first fracture, such as may occur after a fall or trip in the street, both men and women should think about osteoporosis and tell their physician that they have had a fracture. They should seek appropriate investigation for osteoporosis, such as a bone density test, and, if appropriate, treatment to strengthen their bones," added Center.

"Most people tend to think of hip fractures and osteoporosis as things that happen to women. I was amazed to see that the numbers were relatively equal for subsequent fractures. One takeaway from this is that men are not immune to osteoporosis," said Dr. Michael Kelly, chairman of the department of orthopaedic surgery at Hackensack University Medical Center in New Jersey.

He said that men who've had to be treated with steroids or cancer drugs, or men who are smokers, need to be especially aware that their bones may not be as strong.

More information

Here's advice from the National Institute of Arthritis and Musculoskeletal and Skin Diseases on preventing second fractures.