Equine cortical bone exhibits rising R-curve fracture mechanics.
Abstract: Previous studies of the fracture properties of cortical bone have suggested that the fracture toughness increases with crack length, which is indicative of rising R-curve behavior. Based on this indirect evidence and the similarity of bone to ceramic matrix composites, we hypothesized that bone would exhibit rising R-curve behavior in the transverse orientation and that the characteristics of the R-curves would be regionally dependent within the cortex due to variations in bone microstructure and toughening mechanisms. To test these hypotheses, we conducted R-curve experiments on specimens from equine third metacarpal bones using standard fracture mechanics testing methods. Compact type specimens from the dorsal and lateral regions in the middle of the diaphysis were oriented for crack propagation transverse to the longitudinal axis of the bone. The test results demonstrate that equine cortical bone exhibits rising R-curve behavior during transverse crack propagation as hypothesized. Statistical analyses of the crack growth initiation toughness, K0, the peak toughness, Kpeak, and the crack extension at peak toughness, deltaa, revealed significant regional differences in these characteristics. Specifically, the lateral cortex displayed higher crack growth initiation and peak toughnesses. The dorsal cortex exhibited greater crack extension at the peak of crack growth resistance. Scanning electron microscopy revealed osteon pullout on fracture surfaces from the dorsal cortex and but not in the lateral cortex. Taken together, the significant differences in R-curves and the SEM fractography indicate that the fracture mechanisms acting in equine cortical bone are regionally dependent.
Publication Date: 2003-01-28 PubMed ID: 12547356DOI: 10.1016/s0021-9290(02)00362-7Google Scholar: Lookup
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- Journal Article
- Research Support
- U.S. Gov't
- P.H.S.
Summary
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The research article presents a study on the fracture properties of horse cortical bone. It reveals that the bone displays varying fracture toughness characteristics depending on the region of the cortex, exhibiting behavior similar to ceramic matrix composites.
Objective and Hypothesis of the Study
- The aim of the study was to explore the fracture mechanics of cortical bone, specifically in horses. The researchers hypothesized that the cortical bone’s fracture toughness varies depending on the region of the cortex, exhibiting what is called a ‘rising R-curve behavior’ (an increase in fracture toughness with crack length).
R-Curve Experiments and Methodology
- In order to test their hypothesis, the researchers carried out R-curve experiments on equine third metacarpal bones using standard fracture mechanics testing methods.
- They took compact type specimens from the dorsal (back) and lateral (side) areas from the middle part of the bone’s shaft, called the diaphysis. These specimens were tested for crack propagation perpendicular to the length of the bone.
Results and Observations
- The results of the tests confirmed the researchers’ hypothesis that the equine cortical bone displays a rising R-curve behavior during transverse crack propagation.
- There were notable regional differences in the crack growth initiation toughness (K0), the peak toughness (Kpeak), and the crack extension at peak toughness (deltaa)
- The lateral cortex showed higher initiation and peak toughnesses, while the dorsal cortex showed a greater extension at peak crack growth resistance.
Microstructure and Regional Dependence
- Using scanning electron microscopy, the scientists observed osteon (a structural unit in cortical bone) pullout in the fracture surfaces from the dorsal cortex and not in the lateral cortex.
- The significant differences in R-curves and the results from their microscopic analysis suggest that the fracture mechanisms at play in equine cortical bone are regionally dependent, confirming their initial hypothesis.
In conclusion, the study provides valuable insights into the fracture mechanisms of equine cortical bone and how they vary depending upon the region of the cortex. This research can form a basis for future studies into the biomechanical properties of other types of bones or species.
Cite This Article
APA
Malik CL, Stover SM, Martin RB, Gibeling JC.
(2003).
Equine cortical bone exhibits rising R-curve fracture mechanics.
J Biomech, 36(2), 191-198.
https://doi.org/10.1016/s0021-9290(02)00362-7 Publication
Researcher Affiliations
- Biomedical Engineering Graduate Group, University of California, CA 95616, USA.
MeSH Terms
- Animals
- Elasticity
- Fractures, Stress / pathology
- Fractures, Stress / physiopathology
- Horses
- In Vitro Techniques
- Male
- Metacarpus / injuries
- Metacarpus / physiopathology
- Metacarpus / ultrastructure
- Pressure
- Sensitivity and Specificity
- Stress, Mechanical
- Tensile Strength
- Weight-Bearing
Grant Funding
- AR41644 / NIAMS NIH HHS
Citations
This article has been cited 12 times.- Doube M. Closing cones create conical lamellae in secondary osteonal bone.. R Soc Open Sci 2022 Aug;9(8):220712.
- Kataruka A, Mendu K, Okeoghene O, Puthuvelil J, Akono AT. Microscopic assessment of bone toughness using scratch tests.. Bone Rep 2017 Jun;6:17-25.
- Thurner PJ, Katsamenis OL. The role of nanoscale toughening mechanisms in osteoporosis.. Curr Osteoporos Rep 2014 Sep;12(3):351-6.
- Katsamenis OL, Jenkins T, Quinci F, Michopoulou S, Sinclair I, Thurner PJ. A novel videography method for generating crack-extension resistance curves in small bone samples.. PLoS One 2013;8(2):e55641.
- Hambli R. A quasi-brittle continuum damage finite element model of the human proximal femur based on element deletion.. Med Biol Eng Comput 2013 Feb;51(1-2):219-31.
- Nyman JS, Makowski AJ. The contribution of the extracellular matrix to the fracture resistance of bone.. Curr Osteoporos Rep 2012 Jun;10(2):169-77.
- Nazari A, Bajaj D, Zhang D, Romberg E, Arola D. Aging and the reduction in fracture toughness of human dentin.. J Mech Behav Biomed Mater 2009 Oct;2(5):550-9.
- Currey J. Measurement of the mechanical properties of bone: a recent history.. Clin Orthop Relat Res 2009 Aug;467(8):1948-54.
- Dong XN, Guda T, Millwater HR, Wang X. Probabilistic failure analysis of bone using a finite element model of mineral-collagen composites.. J Biomech 2009 Feb 9;42(3):202-9.
- Ritchie RO, Koester KJ, Ionova S, Yao W, Lane NE, Ager JW 3rd. Measurement of the toughness of bone: a tutorial with special reference to small animal studies.. Bone 2008 Nov;43(5):798-812.
- Nalla RK, Kinney JH, Tomsia AP, Ritchie RO. Role of alcohol in the fracture resistance of teeth.. J Dent Res 2006 Nov;85(11):1022-6.
- Hazenberg JG, Taylor D, Lee TC. The role of osteocytes and bone microstructure in preventing osteoporotic fractures.. Osteoporos Int 2007 Jan;18(1):1-8.
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