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Updated: May 9, 2026
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Method and Instrumented Fixture for Femoral Fracture Testing in a Sideways Fall-on-the-Hip Position
Published on: August 17, 2017
Microstructural failure mechanisms in the human proximal femur for sideways fall loading
Shashank Nawathe1, Hosna Akhlaghpour, Mary L Bouxsein
1Department of Mechanical Engineering, University of California, Berkeley, CA, USA.
Summary
Hip fracture risk is linked to how little bone tissue fails, especially trabecular bone in weaker femurs. This finding improves understanding of bone microstructural failure mechanisms during falls.
Area of Science:
- Biomechanics
- Orthopedics
- Gerontology
Background:
- Hip fractures are a significant health issue with unclear causes.
- Understanding proximal femur failure mechanisms during sideways falls is crucial for elucidating fracture etiology.
- Microstructural bone failure is a key area for investigation.
Purpose of the Study:
- To biomechanically test cadaver proximal femurs to measure strength during sideways falls.
- To use micro-computed tomography (CT)-based finite element analysis to estimate internal tissue-level failure.
- To correlate finite element predictions with directly measured bone strength.
Main Methods:
- Biomechanical testing of 12 cadaver proximal femurs.
- Micro-computed tomography (CT) scanning for high-resolution 3D bone models.
- Nonlinear finite element analysis (FEA) with approximately 120 million elements per model.
- Direct measurement of femoral yield strength during simulated sideways falls.
Main Results:
- High correlation (R²=0.94) between measured yield strength and FEA predictions validates the models.
- Initial structural failure of the femur occurred with failure of a small proportion of bone tissue (1.5%–6.4%).
- The proportion of failed tissue decreased with decreasing femoral strength and was more correlated than bone volume, mass, or density.
Conclusions:
- Initial femur failure in sideways falls involves a small amount of bone tissue failure.
- Trabecular bone failure dominates in the weakest femurs, contributing to low structural redundancy.
- Femurs with low strength relative to areal bone mineral density (BMD) show less trabecular bone and reduced structural integrity.
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