Effects of 1 to 3 years' treatment with alendronate on mechanical properties of the femoral shaft in a canine model: Implications for subtrochanteric femoral fracture risk

Authors

  • David B. Burr,

    Corresponding author
    1. Department of Anatomy and Cell Biology, Indiana University School of Medicine, 635 Barnhill Drive, MS259, Indianapolis, Indiana 46202
    2. Department of Orthopedic Surgery, Indiana University School of Medicine
    3. Department of Biomedical Engineering, Indiana University–Purdue University at Indianapolis (IUPUI)
    • Department of Anatomy and Cell Biology, Indiana University School of Medicine, 635 Barnhill Drive, MS259, Indianapolis, Indiana 46202. T: 317-274-7496; F: 317-278-2040.
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  • Tamim Diab,

    1. Department of Anatomy and Cell Biology, Indiana University School of Medicine, 635 Barnhill Drive, MS259, Indianapolis, Indiana 46202
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  • Andrew Koivunemi,

    1. Department of Anatomy and Cell Biology, Indiana University School of Medicine, 635 Barnhill Drive, MS259, Indianapolis, Indiana 46202
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  • Mark Koivunemi,

    1. Department of Anatomy and Cell Biology, Indiana University School of Medicine, 635 Barnhill Drive, MS259, Indianapolis, Indiana 46202
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  • Matthew R. Allen

    1. Department of Anatomy and Cell Biology, Indiana University School of Medicine, 635 Barnhill Drive, MS259, Indianapolis, Indiana 46202
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Abstract

Bisphosphonate (BP) treatment used to prevent bone loss in postmenopausal osteoporosis has recently been implicated in an apparent increase in subtrochanteric femoral fractures. Previous work showed that BPs can reduce the energy to fracture of cancellous bone, but limited data exist on material-level mechanical properties of compact bone from the long bones. This study examined intrinsic mechanical properties of the femoral diaphysis of a canine model treated for 1 or 3 years with alendronate at two different doses. Seventy-two dogs were treated orally with 0.2 mg/kg/day alendronate or 1.0 mg/kg/day alendronate; a control group was administered saline. Prismatic beam specimens were tested in four-point bending under displacement control, and the intrinsic mechanical properties were calculated. No significant differences were found among groups in any mechanical property at either 1 or 3 years of treatment. We conclude that the material properties of the femoral diaphysis are not degraded following 1 to 3 years treatment with alendronate, even at high doses. Longer periods of treatment have not been studied using clinical doses of alendronate, but such studies need to be carried out to confirm a lack of effect of alendronate on mechanical properties of cortical bone in the subtrochanteric region of the femur. © 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 27:1288–1292, 2009

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