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Show UNDERGRADUATE RESEARCH ABSTRACTS SPRING 2007 Adam Beckstrom ^mmKmmtr Roy Bloebaum 13 Interpreting Loading Regimen in Bat and Pigeon Humeri Via Predominant Collagen Fiber Orientation Adam Beckstrom (Roy Bloebaum) VA Bone and Joint Research Laboratory Veterans Affairs Medical Center, Salt Lake City, Utah 84108 Collagen fiber orientation (CFO) is a strong predictor of habitual loading in bones. This parameter might represent a surrogate in situations where it is not possible to apply conventional strain gauges. Collagen fiber orientation can be guantified using birefringent properties of thin sections of bone. Bat/pigeon humeri (experimental bones) are known to experience high amounts of torsion. The goal of this study was to obtain guantitative data from bat/pigeon humeri to establish material characteristics that reliably reflect a bones loading history. Cross sectional segments of the humeri were embedded in PMMA and prepared via ultramilling technigues to a uniform thickness. These sections were then viewed and imaged under circularly polarized light to obtain a weighted mean greylevel at the dorsal, ventral, medial and lateral cortices. The values for each guadrant were then compared to each other as well as to the values obtained previously for our control bones. We observed that both the bat and pigeon humeri exhibited no regional differences in CFO across the four guadrants. This is typical of bones adapted for shear resulting from their highly torgued environment. Our experimental bones also differed significantly from deer and sheep calcanei (control bones), which experience simple bending, having tension and compression regions on opposing sides of the bone. |