During childhood, the incidence of distal forearm fractures (those located near the wrist) typically peaks around age 12 in girls and 14 in boys. Previous studies have documented that most of these fractures occur around the time of the growth spurt during puberty.
"Our study examined whether these fracture rates have changed over time, and the data would indicate that there has been a substantial increase in these fractures that is of some concern," says Sundeep Khosla, M.D., a Mayo Clinic endocrinologist and the study's primary investigator.
Supported by the National Institute on Aging, Mayo Clinic researchers recorded the number of forearm fractures that occurred in people under age 35 who lived in Rochester, Minn., during four defined time periods. A previous study had published these data from 1969-1971. Dr. Khosla's team re-examined these data and looked at the same population 10, 20 and 30 years later in 1979-1981, 1989-1991 and 1999-2001.
The most significant finding was that the forearm fracture rate among young people increased by 42 percent, from 265 per 100,000 people annually in 1969-1971, to 469 per 100,000 in 1999-2001.
"That 42 percent increase in forearm fractures is mostly due to increased fractures among people under age 20," says Dr. Khosla.
Looking at the years 1999-2001, girls between 8 and 11 and boys between 11 and 14 had higher fracture rates than all other age groups studied. And 12-year-old boys had the highest fracture rate of all, 1,536 per 100,000 people, or 1.5 percent per year.
Mayo Clinic researchers also grouped the fractures by categories, including those caused by disease, serious trauma (including car accidents, serious falls, and recreational and occupational injuries) or moderate trauma (such as a minor fall). The incidence of fractures associated with recreational activities almost doubled. This category included both team sports such as baseball and football, and individual sports such as skating and rollerblading.
Many experts have theorized that forearm fractures that occur during adolescence are related to the fact that bones become more porous during growth spurts. However, the fracture rate increase documented by Mayo Clinic researchers paints a picture that requires further study.
"Our study does not explain why these fracture rates increased, but the data raise concerns about whether bone-mass development in today's children may be impaired by other lifestyle and dietary factors such as increased soft drink consumption, decreased milk consumption or changing patterns of physical activity," says Dr. Khosla.
Adequate bone-mass development during childhood is critical to preventing osteoporosis and the related bone fractures that can occur later in life.
"Increasing rates for forearm fractures in children could mean we will see a dramatic increase in the risk for hip fractures and other more serious fractures when these children become older adults," explains L. Joseph Melton III, M.D., a coinvestigator in the study and an expert on the epidemiology of osteoporosis.
Tuesday, Sept. 16, 2003
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