Osteoporosis International

, Volume 22, Issue 5, pp 1377–1388

Ethnic differences in femur geometry in the women's health initiative observational study

  • D. A. Nelson
  • T. J. Beck
  • G. Wu
  • C. E. Lewis
  • T. Bassford
  • J. A. Cauley
  • M. S. LeBoff
  • S. B. Going
  • Z. Chen
Original Article

DOI: 10.1007/s00198-010-1349-4

Cite this article as:
Nelson, D.A., Beck, T.J., Wu, G. et al. Osteoporos Int (2011) 22: 1377. doi:10.1007/s00198-010-1349-4

Abstract

Summary

Participants in the observational study of the Women's Health Initiative (WHI) were studied to determine if ethnic differences in femur geometry can help to explain differences in hip fracture rates. Structural differences in femurs of African and Mexican-American women appear to be consistent with lower rates of hip fractures vs. whites.

Introduction

Ethnic origin has a major influence on hip fractures, but the underlying etiology is unknown. We evaluated ethnic differences in hip fracture rates among 159,579 postmenopausal participants in the WHI then compared femur bone mineral density (BMD) and geometry among a subset with dual X-ray absorptiometry (DXA) scans of the hip and total body.

Methods

The subset included 8,206 non-Hispanic whites, 1,476 African-American (AA), 704 Mexican-American (MA), and 130 Native Americans (NA). Femur geometry derived from hip DXA using hip-structure analysis (HSA) in whites was compared to minority groups after adjustment for age, height, weight, percent lean mass, neck-shaft angle and neck length, hormone use, chronic disease (e.g., diabetes, rheumatoid arthritis, cancer), bone active medications (e.g., corticosteroids, osteoporosis therapies), and clinical center.

Results

Both AA and MA women suffered hip fractures at half the rate of whites while NA appeared to be similar to whites. The structural advantage among AA appears to be due to a slightly narrower femur that requires more bone tissue to achieve similar or lower section moduli (SM) vs. whites. This also underlies their higher BMD (reduces region area) and lower buckling ratios (buckling susceptibility). Both MA and NA women had similar advantages vs. whites at the intertrochanter region where cross-sectional area and SM were higher but with no differences at the neck. NA and MA had smaller bending moments vs. whites acting in a fall on the hip (not significant in small NA sample). Buckling ratios of MA did not differ from whites at any region although NA had 4% lower values at the IT region.

Conclusion

Differences in the geometry at the proximal femur are consistent with the lower hip fracture rates among AA and MA women compared to whites.

Keywords

African American Cross-sectional geometry Ethnic differences Hip structure analysis Local buckling Mexican American Native American Proximal femur 

Copyright information

© International Osteoporosis Foundation and National Osteoporosis Foundation 2010

Authors and Affiliations

  • D. A. Nelson
    • 1
  • T. J. Beck
    • 2
  • G. Wu
    • 3
  • C. E. Lewis
    • 4
  • T. Bassford
    • 3
  • J. A. Cauley
    • 5
  • M. S. LeBoff
    • 6
  • S. B. Going
    • 3
  • Z. Chen
    • 3
  1. 1.Wayne State University School of MedicineDetroitUSA
  2. 2.Johns Hopkins University School of MedicineBaltimoreUSA
  3. 3.Mel and Enid Zuckerman College of Public HealthUniversity of ArizonaTucsonUSA
  4. 4.University of Alabama BirminghamBirminghamUSA
  5. 5.Brigham and Womens Hospital, Harvard Medical SchoolBostonUSA
  6. 6.University of Pittsburgh Graduate School of Public HealthPittsburghUSA

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