Osteonal structure in the equine third metacarpus.
Abstract: In studying the flexural fatigue properties of the equine third metacarpal (cannon) bone, we previously found that the dorsal region was weaker monotonically, but more fatigue resistant, than the lateral region. Fatigue resistance was associated with fracture surfaces which demonstrated that secondary osteons had "pulled out" of the surrounding matrix; this never happened in lateral specimens. We therefore became interested in the osteonal structure of this bone, and began to study its birefringence patterns in circularly polarized light. We found that the predominant type of secondary osteon was one in which only the outermost few lamellae were circumferential, with the inner lamellae being longitudinally oriented. This "hoop" pattern had not been described in Ascenzi's classic papers. Using basic fuchsin-stained, undecalcified cross-sections from the dorsal, medial, and lateral midshaft regions of 12 pairs of cannon bones, we classified 360 secondary osteons according to their birefringence patterns, and measured their inner and outer diameters. We found that variants of the hoop category comprised 60% of all osteons, but were significantly less common in the dorsal region, where the predominant types were Ascenzi's "longitudinal" or "alternating" patterns. The dorsal region also had smaller osteons (OD = 156 +/- 19 microns) than the medial (179 +/- 13 microns, p = 0.0004) and lateral (182 +/- 13 microns, p = 0.0001) regions. We postulate that these regional variations in osteonal size and structure, which are obviously produced by regional variations in remodeling, have important mechanical implications.
Publication Date: 1996-08-01 PubMed ID: 8853861DOI: 10.1016/8756-3282(96)00167-6Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
- Research Support
- U.S. Gov't
- P.H.S.
Summary
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The study focuses on the osteonal structure of the third metacarpal bone (cannon bone) in horses, reporting that the dorsal region of the bone is weaker yet more fatigue resistant, linked to the unique patterns of secondary osteons and their relation with birefringence when viewed through polarized light.
Objective of the Study
- The study aimed at understanding the osteonal structure of the equine third metacarpal bone and its flexural fatigue properties. The researchers noted a pattern where secondary osteons had “pulled out” of the surrounding matrix in dorsal bone specimens, which sparked the interest in the bone’s osteonal structure.
Methodology
- The team examined the bone’s birefringence patterns in circularly polarized light, looking specifically for the orientation of its osteons or the lamellar structures that make up the bone.
- The research involved studying basic fuchsin-stained, undecalcified cross-sections from dorsal, medial, and lateral midshaft regions of 12 pairs of cannon bones.
- Around 360 secondary osteons were classified according to their birefringence patterns, and their inner and outer diameters were measured.
Findings
- 60% of all osteons were found to be a variant of the “hoop” pattern, where only the outermost lamellae were circumferential, with the inner lamellae being longitudinally oriented. However, these “hoop” patterned osteons were significantly less common in the dorsal region.
- The predominant types in the dorsal region were Ascenzi’s “longitudinal” or “alternating” patterns, indicating a possible link to its greater fatigue resistance.
- Dorsal region osteons were also smaller (156 +/- 19 microns) compared to the medial (179 +/- 13 microns) and lateral (182 +/- 13 microns) regions.
Conclusions
- The researchers concluded that these described regional variations in osteonal size and structure, which arise from variations in remodeling, may have significant mechanical implications that could explain observed differences in strength and fatigue resistance among different bone regions.
Cite This Article
APA
Martin RB, Gibson VA, Stover SM, Gibeling JC, Griffin LV.
(1996).
Osteonal structure in the equine third metacarpus.
Bone, 19(2), 165-171.
https://doi.org/10.1016/8756-3282(96)00167-6 Publication
Researcher Affiliations
- Orthopedic Research Laboratory, School of Medicine, University of California at Davis, USA. rbmartin@ucdavis.edu
MeSH Terms
- Analysis of Variance
- Animals
- Birefringence
- Chi-Square Distribution
- Female
- Fractures, Stress / pathology
- Haversian System / anatomy & histology
- Horses / anatomy & histology
- Male
- Metacarpus / anatomy & histology
- Tensile Strength
Grant Funding
- AR41644 / NIAMS NIH HHS
Citations
This article has been cited 6 times.- Nguyen JT, Barak MM. Secondary osteon structural heterogeneity between the cranial and caudal cortices of the proximal humerus in white-tailed deer.. J Exp Biol 2020 Jun 11;223(Pt 11).
- Cummaudo M, Cappella A, Giacomini F, Raffone C, Màrquez-Grant N, Cattaneo C. Histomorphometric analysis of osteocyte lacunae in human and pig: exploring its potential for species discrimination.. Int J Legal Med 2019 May;133(3):711-718.
- Campbell AM, Cler ML, Skurla CP, Kuehl JJ. Damage accumulation of bovine bone under variable amplitude loads.. Bone Rep 2016 Dec;5:320-332.
- Harrison KD, Cooper DM. Modalities for Visualization of Cortical Bone Remodeling: The Past, Present, and Future.. Front Endocrinol (Lausanne) 2015;6:122.
- Skedros JG, Kiser CJ, Keenan KE, Thomas SC. Analysis of osteon morphotype scoring schemes for interpreting load history: evaluation in the chimpanzee femur.. J Anat 2011 May;218(5):480-99.
- Bentley VA, Sample SJ, Livesey MA, Scollay MC, Radtke CL, Frank JD, Kalscheur VL, Muir P. Morphologic changes associated with functional adaptation of the navicular bone of horses.. J Anat 2007 Nov;211(5):662-72.
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