Related Experiment Videos
Limitations of the continuum assumption in cancellous bone
T P Harrigan1, M Jasty, R W Mann
1Department of Mechanical Engineering, Massachusetts Institute of Technology.
Journal of Biomechanics
|January 1, 1988
Summary
The continuum assumption for cancellous bone is invalid near interfaces or high stress gradients. Density accuracy limits indicate when this bone modeling approach is unreliable.
Area of Science:
- Biomechanics
- Skeletal analysis
- Materials science
Background:
- Cancellous bone is often modeled as a continuum in stress analyses.
- The validity of this continuum assumption is not well-defined, especially near biologic interfaces and in regions with significant stress variations.
Purpose of the Study:
- To develop a criterion for assessing the validity of the continuum assumption for cancellous bone.
- To identify the limitations of continuum models in skeletal stress analysis.
Main Methods:
- Development of a probabilistic line scanning model for bone density measurement.
- Experimental verification of the model's prediction of density accuracy as a function of line length.
Main Results:
- The continuum model is questionable within three to five trabeculae of an interface.
- Continuum analysis results are suspect if they vary by more than 20-30% over a distance of three to five trabeculae.
Conclusions:
- The continuum assumption for cancellous bone has specific limitations near interfaces and in areas of high stress gradients.
- A probabilistic line scanning model provides a method to estimate density accuracy and determine the reliability of continuum models in specific regions.