TUESDAY, Sept. 16, 2003 (HealthDayNews) -- Kids are breaking their wrists and forearms far more often than they did 30 years ago.
Experts don't yet know what's behind this increase, but it does raise the possibility that children and teens aren't getting enough calcium and, as a result, have lower bone density. This, in turn, raises the specter that these same kids may develop osteoporosis as they age.
"Adolescence is critical for bone mass acquisition. It is estimated that a quarter of bone mass in adult women and men is accumulated during the adolescent growth spurt," says Dr. Sundeep Khosla, lead author of a National Institute on Aging-sponsored study appearing in the Sept. 17 issue of the Journal of the American Medical Association.
"The fact that we've seen this fairly significant increase in forearm fractures in the past 30 years raises the concern that these kids aren't acquiring the optimal peak bone mass that they should," Khosla says.
The number of distal forearm fractures (those located near the wrist) usually peaks around age 12 in girls and 14 in boys. This coincides with the time of the growth spurt during puberty, and many researchers have hypothesized that the breaks occur because bones are more vulnerable at this critical time.
The new data, however, raise additional questions.
For this study, Mayo Clinic researchers analyzed the number of forearm fractures occurring in people under the age 35 who lived in Rochester, Minn., during four distinct time periods: 1969 to 1971, 1979 to 1981, 1989 to 1991 and 1999 to 2001.
From 1969-1971 to 1999-20001, the forearm fracture rate increased by 42 percent. In the earlier period, 265 per 100,000 people broke their forearm annually, compared with 469 per 100,000 in 1999-2001. Most of these fractures occurred in people under the age of 20.
Among males, the incidence of fractures was 32 percent greater in the later period and 56 percent greater among females in 1999-2001.
The incidence of fractures due to recreational activities almost doubled.
"Certainly recreation changes," says Dr. Stephen Honig, director of the Osteoporosis Center at the Hospital for Joint Diseases in New York City. "Girls are doing more sports. There's also in-line skating and other things including snowboarding. These are higher impact activities."
Khosla, who is a professor of medicine at the Mayo Clinic in Rochester, Minn., points out that reasons for the increase could include increased physical activity as well as an increase in obesity, which would put a greater load on the bones when a child falls.
"But among these possibilities is that they're not acquiring optimal bone mass because they're not getting enough milk," he adds.
The study authors point out that between 1977 and 1996, the consumption of soft drinks among girls aged 12 to 19 increased from 207 to 396 grams per day, while milk consumption fell from 303 to 189 grams.
"That would suggest that they're substituting for dairy products," Khosla says. Overall calcium intake fell slightly from 784 to 771 milligrams per day for girls and remained about the same for boys, although both values were below the recommended dietary allowance.
Further studies are needed to see what characteristics might distinguish kids who have fractures versus those who don't -- in other words, is there a difference in level of activity or obesity. Also, researchers need to follow these kids into adulthood to see if they continue to have lower bone density and more osteoporotic fractures as they age.
Still, a number of questions remain unanswered, Honig says.
"If you see someone in their 50s, you're not sure if they're having new bone loss or if it's a consequence of never having high enough peak bone mass to begin with," Honig says. "Only the future will tell us where we are with this."