Osteoporosis May Be Cause of High-Trauma Bone Fractures

SAN FRANCISCO, Nov. 27 -- Many bone fractures suffered by older patients in car crashes and other high-trauma events may be the result of osteoporosis, rather than the trauma itself, researchers here found.
Action Points
Explain that the study's main finding was that some high-trauma fractures in older patients, such as might be sustained in a car crash or other violent event, might be a result of osteoporosis.
Explain that, as a result, it may be worthwhile to examine older people who have these fractures for the possible presence of osteoporosis.
In women, each decrease of one standard deviation in total hip bone mineral density (BMD) was associated with a 47% increase in the age-adjusted, five-year risk of suffering high-trauma fracture (95% CI: 28% to 69%), reported Dawn C. Mackey, M.Sc., of the California Pacific Medical Center Research Institute, and colleagues in the Nov. 28 issue of the Journal of the American Medical Association.
An even greater increase in risk was found in men: 58% for each standard deviation of total hip BMD lost (95% CI: 27% to 97%), they found.
Smaller but still significant increases in risk of high-trauma fracture were correlated with decreased BMD at the femoral neck and lumbar spine. The correlation was stronger in men than in women for BMD measurements in those locations, the researchers said.
Yet, they noted, "there is a pervasive clinical opinion that an older adult who has a high-trauma fracture does not require evaluation for osteoporosis."
In the first study to look prospectively at the relationship between bone mineral density and incidence of high-trauma fractures, the researchers noted that the increased risk for high-trauma fractures was similar to that found for low-trauma fractures, the kind more usually associated with osteoporosis.
"High-trauma non-spine fractures should be considered potential osteoporotic fractures and should receive similar clinical management as low-trauma non-spine fractures," the researchers said.
Other study findings supported a role for osteoporosis in high-trauma fractures. For example, women in the study who had these fractures were 34% more likely to incur another fracture later on, compared with those who did not suffer a high-trauma fracture.
The analysis was based on data from two similar prospective studies of adults 65 or older, with more than 14,000 participants.
More than 8,000 women taking part in the Study of Osteoporotic Fractures were followed for an average of 9.1 years. Nearly 6,000 men were tracked for a mean of 5.1 years in the Osteoporotic Fractures in Men Study.
During these studies, subjects were asked every four months if they had suffered fractures during the previous four months. Records were complete for more than 95% of the women and 99% of the men.
High-trauma fractures occurred in 264 women and 94 men. About 3,200 women and 350 men had low-trauma fractures.
For both sexes, individuals who had high-trauma fractures as well as low-trauma fractures had significantly lower bone mineral density at the hip, femoral neck and lumbar spine compared with those who did not suffer fractures (P0.05). There were no important differences in BMD between those with high-trauma versus low-trauma fractures.
For women, each 1-SD reduction in total hip BMD was similarly associated with an increased risk of high-trauma fracture (multivariate relative hazard: 1.45, 95% confidence interval: 1.23 to 1.72) and low-trauma fracture (RH: 1.49, 95% CI: 1.42 to 1.57). Results were consistent in men (high-trauma fracture RH: 1.54, 95% CI: 1.20 to 1.96; low-trauma fracture RH: 1.69, 95% CI: 1.49 to 1.91).
Risk of subsequent fracture was 34% (95% CI: 7% to 67%) greater among women with an initial high-trauma fracture and 31% (95% CI: 20% to 43%) greater among women with an initial low-trauma fracture, compared with women having no high- or low-trauma fracture, respectively.
"The clinical implications of this study are important," said Sundeep Khosla, M.D., of the Mayo Clinic in Rochester, Minn., in an accompanying editorial.
"Fractures previously defined as caused by high trauma, such as those from a blunt injury in a motor vehicle crash or a fall from a chair, can no longer be dismissed as being unrelated to osteoporosis," Dr. Khosla said. "Older patients who sustain such fractures should be considered for BMD testing and, if clinically indicated, further evaluation for osteoporosis."
Both Dr. Khosla and the researchers said the findings indicate that current definitions of high-trauma fracture unrelated to BMD loss need to be rewritten.
There is a need for further investigation, Dr. Khosla wrote, "to examine more closely the specific fractures classified as high-trauma fractures and subsequently to identify those that are related to BMD [versus] those representing such severe force that virtually any bone would fracture, regardless of BMD."
The researchers also recommended that future clinical trials in osteoporosis include high-trauma fractures as outcome measures, and Dr. Khosla concurred.
Failing to classify these fractures as potentially osteoporosis-related detracts from the applicability of clinical studies, the researchers said.
They acknowledged some limitations of their data, including the fact that their study did not evaluate spinal fractures, and also did not adjust for bisphosphonate drug use in women (the drugs were not available when the SOF study began in 1988). In addition, as all patients in this study were over the age of 65, the conclusions may not be generalizable to younger patients.
The Study of Osteoporotic Fractures is supported by Public Health Service research grants from the National Institutes of Health. The Osteoporotic Fractures in Men Study is supported by National Institutes of Health funding.
Several co-authors of the study reported financial relationships with the following companies: Amgen, Aventis, Novartis, NPS Pharmaceuticals, Eli Lilly, Wyeth, Merck, Pfizer, GlaxoSmithKline, Procter & Gamble, Roche, Organon, Johnson & Johnson, Kyphon, Tethys, and Zelos. Primary source: JAMASource reference: Mackey D, et al "High-trauma fractures and low bone mineral density in older women and men" JAMA 2007; 298: 2381-88. Additional source: JAMASource reference: Khosla S, "High-trauma fractures and bone mineral density" JAMA 2007; 298: 2418-19.