Fig. 1 3-D reconstruction of high-resolution peripheral computed tomography (HR-pQCT) image of the distal radius in a representative premenopausal woman with distal radius fracture (top) and similarly aged woman with no history of fracture (bottom). Note the trabecular and cortical bone deficits in the fracture CT compared to the control.
Courtesy of Tamara D. Rozental, MD

AAOS Now

Published 11/1/2011
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Maureen Leahy

Early skeletal fragility not easy to spot

By Maureen Leahy

Study supports development of new clinical models to identify young women at risk for osteoporosis

Current osteoporosis management strategies focus on identifying postmenopausal women with low bone mineral density (BMD) who are at increased risk for fractures. According to study data presented at the American Society for Surgery of the Hand (ASSH) annual meeting, however, premenopausal patients with distal radius fractures exhibit evidence of early skeletal fragility that may not be evident with a simple dual-energy X-ray absorptiometry (DXA) scan. This provides a strong rationale for developing new clinical models to identify younger women who are at risk for the disease, say the study authors.

According to the literature, BMD may not accurately reflect fracture risk, and up to 50 percent of women with hip and other nonvertebral fractures do not have osteoporosis as defined by BMD measurements. In addition, recent studies have found that women experience a significant decline in trabecular bone mass and architecture before menopause. Tamara D. Rozental, MD, and her fellow researchers hypothesized, therefore, that premenopausal women with distal radius fractures would have altered microarchitecture, but similar BMD, compared to premenopausal women with no history of such fractures.

“Distal radius fractures are most common in young adults and in postmenopausal women, and they occur in adults at a younger age than hip/spine fractures. In addition, forearm and wrist fractures are associated with lower BMD in the pediatric literature. For these reasons, we thought this would be an important cohort to study in the setting of fragility fractures,” Dr. Rozental said.

Matching patients to controls
In the prospective study, premenopausal women with distal radius fractures (n = 28; average age: 29.3 years; average body mass index [BMI]: 26.5) were matched to a nonfracture control group (n = 82; average age: 26.8 years; average BMI: 24.6). Fracture patients had a documented history of wrist fracture within 3 months of seeing the surgeon; 19 fractures were sustained from a fall from a standing height and nine were the result of high-energy sports. Nondisplaced fractures were treated with casting until union; displaced fractures were offered surgical treatment at the discretion of the treating surgeon.

Control patients had no history of fractures as adults. Women with eating disorders, endocrinopathies (insulin-dependent diabetes mellitus, thyroid disease), or metabolic bone disease, and those who were pregnant, were excluded in both groups. Additional exclusion criteria included exposure to glucocorticoids and immunosuppressive medications, and treatment with hormone replacement therapy, bisphosphonates, parathyroid hormone, selective estrogen receptor modulators, or aromatase inhibitors.

Bone microarchitecture, density
The researchers used high-resolution peripheral quantitative computed tomography (HR-pQCT) scans of the distal radius and distal tibia to examine trabecular and cortical microarchitecture in both groups. DXA scans were used to measure BMD at the wrist, hip, and lumbar spine in all patients. The average time between fracture and scan acquisition was 55 days.

Although BMD values at the wrist, hip, and spine were similar in both groups, analysis at the distal radius found that, compared to the control group, the fracture group had the following values:

  • 8 percent lower total density (P = 0.03)
  • 10 percent lower trabecular density (P = 0.02)
  • 8 percent lower trabecular thickness (P = 0.01)
  • 10 percent lower trabecular bone volume (P = 0.02)

Although the fracture group also had greater trabecular separation and decreased trabecular thickness compared to the control group, the differences were not statistically significant, noted Dr. Rozental. Significant differences in mean cortical thickness, cortical area, or periosteal perimeters were not detected between the two groups.

“We found considerable differences in bone microarchitecture in fracture patients compared to nonfracture controls; women with fractures also had lower bone density, trabecular density, and trabecular thickness at both the distal radius and distal tibia,” said Dr. Rozental. “None of these differences were detected with BMD by DXA, suggesting that HR-p CT detects differences in bone architecture that are not measured by DXA alone.”

She added, “Although its current use may be limited because of its lack of availability, HR-p CT does give us the potential to identify early stages of skeletal fragility. Ideally, being able to identify women at risk for osteoporosis at a young age will provide us with a unique opportunity to initiate early treatment and prevention.”

This study was supported by a clinical research grant from the Ruth Jackson Orthopaedic Society and Sanofi Aventis.

For more information on bone health issues in younger patients, see “Problem bone health: It’s not just an issue for older women,” on page 43.

Dr. Rozental’s coauthors of “Postmenopausal Women with Distal Radius Fractures Have Deteriorated Trabecular Bone Density and Morphology Compared to Nonfracture Controls,” include Mary Bouxsein, PhD; Charles S. Day, MD, MBA; Brandon E. Earp, MD; Laura N. Deschamps, BA; and Alexander P. Taylor, BA.

Disclosure information: Drs. Rozental, Earp, and Bouxsein—no conflicts; Dr. Day—Boston Scientific, Small Bone Innovations; Ms. Deschamps and Mr. Taylor—no conflicts.

Maureen Leahy is assistant managing editor of AAOS Now. She can be reached at leahy@aaos.org

Bottom line

  • Current osteoporosis management strategies do not include identifying premenopausal women who may be at increased risk for fracture.
  • Premenopausal women with distal radius fractures may have evidence of osteoporosis that isn’t being measured yet.
  • Sophisticated imaging technology such as HR-pQCT may detect differences in bone architecture that are not measured by DXA.
  • Although this cross-sectional study doesn’t enable future fracture prediction, its results suggest that fractures at a young age may be risk factors for subsequent fracture and provide a strong rationale for new clinical paradigms to identify young women at risk for osteoporosis.

References

  1. Stone KL, Seeley DG, Lui LY, et al: BMD at multiple sites and risk of fracture of multiple types: Long-term results from the Study of Osteoporotic Fractures. J Bone Miner Res 2003;18(11):1947-1954.
  2. Wainright SA, Marshall LM, Ensrud KE, et al: Hip fracture in women without osteoporosis. J Clin Endocrinol Metab 2005;90(5):2787-2793.
  3. Schuit SC, van der Klift M, Weel AE, et al: Fracture incidence and association with bone mineral density in elderly men and women: The Rotterdam Study. Bone 2004;34(1):195-202.
  4. Khosla S, Riggs BL, Atkinson EJ, et al: Effects of sex and age on bone microstructure at the ultradistal radius: A population-based noninvasive in vivo assessment. J Bone Miner Res 2006;21(1):124-131.
  5. Riggs BL, Melton LJ, Robb RA, et al: A population-based assessment of rates of bone loss at multiple skeletal sites: Evidence for substantial trabecular bone loss in young adult women and men. J Bone Miner Res 2008;23(2):205-214.