Characterization of Loading Environment on Human Ribs during Ventilation
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Date
2016-05
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The Ohio State University
Abstract
The human thoracic cavity holds vital organs, such as the heart and lungs. The rib cage provides protection to these organs, and as a result is susceptible to injuries. One important determinant in the susceptibility of ribs, and bone in general, to fracture is the accumulation of microfractures. These microfractures occur in ribs due to cyclic loading and stress during normal ventilation. Since microfractures accumulate in regions of bone that experience high local strains, it is important to measure the strain patterns ribs experience during the regular loading environment of breathing. The strain mode of the cutaneous cortex and pleural cortex of the rib is unknown and failing to account for how the rib responds to the loading (i.e., initiates microfractures) will affect the accuracy of a physiological model. The objective of this study was to determine the strain modes and magnitudes experienced by the ribs during ventilation. One Post-Mortem Human Surrogate (PMHS) was instrumented with strain gages on the pleural and cutaneous surfaces of ribs 3-9, along with two strain gages on the sternum, resulting in a total of 86 gages. A bladder and air pump were used to mimic ventilation in a defined combination of shallow and deep breaths. Results include location comparisons in strain between bilateral rib pairs, quantification of variation in strain mode (tension versus compression) based on location, and differences in strain magnitudes along the length of the rib. These results will improve researchers’ understanding of physiological strain in the ribs during ventilation and potential for microfracture initiation and repair. A greater comprehension of fracture susceptibility will help researchers improve biofidelic models and their understanding of the loading environment to which the rib is adapted.
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Keywords
Rib Loading Environment, Strain Mode of Rib, Strain Magnitude of Rib, Human Ventilation Model