title: Variability ofin vivolinear microcrack accumulation in the cortex of elderly human ribs.
abstract: Excessive accumulation of microdamage in the skeletonin vivois believed to contribute to fragility and risk of fracture, particularly in the elderly. Current knowledge of how muchin vivodamage accrual varies between individuals, if at all, is lacking. In this study, paired sixth ribs from five male and five female elderly individuals (76-92 years, mean age = 84.7 years) were examined usingen blocstaining and fluorescent microcopy to quantify linear microcracks present at the time of death (i.e. in vivomicrodamage). Crack number, crack length, crack density, and crack surface density were measured for each complete cross-section, with densities calculated using the variable of bone area (which accounts for the influence of porosity on the cortex, unlike the more frequently used cortical area), and analyzed using a two-way mixed model analysis of variance. Results indicate that while microcracks between individuals differ significantly, differences between the left and right corresponding pairs within individuals and the pleural and cutaneous cortices within each rib did not. These results suggest that systemic influences, such as differential metabolic activity, affect the accumulation of linear microcracks. Furthermore, variation in remodeling rates between individuals may be a major factor contributing to differential fracture risk in the elderly. Future work should expand to include a wider age range to examine differences inin vivomicrodamage accumulation across the lifespan, as well as considering the influence of bisphosphonates on microdamage accumulation in the context of compromised remodeling rates in the elderly.
authors.affiliation: Skeletal Biology Research Lab, Injury Biomechanics Research Center, The Ohio State University, 333 W. 10th Ave., Columbus, OH 43210, USA; Department of Anthropology, The Ohio State University, 174 W. 18th Ave., Columbus, OH 43210, USA.
authors.forename: Amanda M
authors.initials: AM
authors.lastname: Agnew
authors.affiliation: Skeletal Biology Research Lab, Injury Biomechanics Research Center, The Ohio State University, 333 W. 10th Ave., Columbus, OH 43210, USA.
authors.forename: Victoria M
authors.initials: VM
authors.lastname: Dominguez
authors.affiliation: Department of Anthropology, The Ohio State University, 174 W. 18th Ave., Columbus, OH 43210, USA.
authors.forename: Paul W
authors.initials: PW
authors.lastname: Sciulli
authors.affiliation: Department of Anthropology, The Ohio State University, 174 W. 18th Ave., Columbus, OH 43210, USA.
authors.forename: Sam D
authors.initials: SD
authors.lastname: Stout
keywords: Bone loss; Bone quality; Fracture risk; Fragility; Microdamage