Fractures are the second most common presentation of child abuse, soft tissue injury being the most common. Femurs are the most common long-bone fractured in inflicted injury. When a child presents to the emergency department, a clinician must judge if the childs fracture matches the account provided by the caregiver. An objective tool is needed to aid in the assessment of injury plausibility. Predicting femur fracture strength is key to developing this tool. Immature porcine femurs are widely used to model pediatric human femurs. This study investigated immature porcine femur fracture load, energy to failure and stiffness in three-point bending, torsion and axial compression, with and without soft tissue intact and at different displacement rates.
Significant differences exist between three point bending with soft tissue intact (n=6) and devoid of soft tissue (n=6) for stiffness (means=1607.9 lbf/in. and 1981.9 lbf/in, respectively, p=0.046) and energy to failure (means=36.9 in-lbf and 25.0 in-lbf, respectively, p=0.046). Torsion tests show significant differences in the fracture torque between groups tested at 0.167 degrees/sec (n=7) and 90 degrees/sec (n=7, means=30.69 in-lbf and 46.13 in-lbf, respectively, p=0.018). Axial compression experiments at 0.04 in/sec (n=5) resulted in fracture load, energy to failure and stiffness of 273.4 lbf, 70.7 in-lbf and 829.4 lbf/in, respectively, while axial compression experiments at 2 in/sec (n=2) resulted in higher fracture loads, energy to failure and stiffness (441 lbf, 154.2 in-lbf and 1894 lbf/in, respectively).
Three-point bending tests resulted in oblique or transverse fractures, torsion and axial compression tests resulted in spiral and growth plate fractures, respectively. Correlations between bone mineral density and structure geometry showed promise as a predictive model for femur fracture response in all loading mechanisms. Multivariable regression modeling resulted in high R2 values (0.62 0.74) for femurs tested with soft tissue intact in three-point bending, but low values (0.22 0.29) for femurs tested devoid of soft tissue in three-point bending; relatively high R2 values (0.66 0.78) for fracture torque in torsion and low R2 values (0.22 0.47) for energy to failure in torsion. Further investigation with a larger sample is needed to reliably predict immature femur fracture response.
| Identifer | oai:union.ndltd.org:PITT/oai:PITTETD:etd-10302004-161405 |
| Date | 28 January 2005 |
| Creators | Aguel, Fernando |
| Contributors | Gina Bertocci, Ph.D., Mary Clyde Pierce, M.D., Richard Debski, Ph.D. |
| Publisher | University of Pittsburgh |
| Source Sets | University of Pittsburgh |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.library.pitt.edu/ETD/available/etd-10302004-161405/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University of Pittsburgh or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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