title: Age and sex alone are insufficient to predict human rib structural response to dynamic A-P loading.
abstract: Thoracic injuries from motor vehicle crashes (MVCs) are common in children and the elderly and are associated with a high rate of mortality for both groups. Rib fractures, in particular, are linked to high mortality rates which increase with the number of fractures sustained. Anthropomorphic test devices (ATDs) and computational models have been developed to improve vehicle safety, however these tools are constructed based on limited physical datasets. To-date, no study has explored variation of rib structural properties across the entire age spectrum with data obtained using the same experimental methodology to allow for comparison. One-hundred eighty-four ribs from 93 post mortem human subjects (PMHS) (70 male, 23 female; ages 4-99) were subjected to dynamic bending tests simulating a frontal impact to the thorax. Structural mechanical properties were calculated and a multi-level statistical model quantified the sample variance as explained by age and sex. Displacement (δX), peak force (Fpeak), linear structural stiffness (K), energy absorption to fracture (Utot), and plastic properties including post-yield energy absorption (UPl), plastic displacement (δPl), and the ratio of elastic to secant stiffness (K-ratio) all showed negative relationships with age, while only Fpeak, K, and Utotwere dependent on sex. Despite these relationships being statistically significant, only 7-39% of variance is explained by age and only 3-17% of variance is explained by sex. This demonstrates that variability in bone properties is more complex than simply chronological age- and sex-dependence and should be explored in the context of biological mechanisms instead.
authors.affiliation: The Ohio State University, Injury Biomechanics Research Center, 2063 Graves Hall, 333 West 10th Avenue, Columbus, OH 43210, United States.
authors.forename: Michelle A
authors.initials: MA
authors.lastname: Schafman
authors.affiliation: The Ohio State University, Injury Biomechanics Research Center, 2063 Graves Hall, 333 West 10th Avenue, Columbus, OH 43210, United States.
authors.forename: Yun-Seok
authors.initials: YS
authors.lastname: Kang
authors.affiliation: National Highway Traffic Safety Administration (NHTSA), Vehicle Research & Test Center (VRTC), P.O. Box B37, 10820, SR 347, East Liberty, OH 43319-0337, United States.
authors.forename: Kevin
authors.initials: K
authors.lastname: Moorhouse
authors.affiliation: The Ohio State University, Division of Health Information Management and Systems, 543 Atwell Hall, 453 10th Avenue, Columbus, OH 43210, United States.
authors.forename: Susan E
authors.initials: SE
authors.lastname: White
authors.affiliation: The Ohio State University, Injury Biomechanics Research Center, 2063 Graves Hall, 333 West 10th Avenue, Columbus, OH 43210, United States.
authors.forename: John H
authors.initials: JH
authors.lastname: Bolte
authors.affiliation: The Ohio State University, Injury Biomechanics Research Center, 2063 Graves Hall, 333 West 10th Avenue, Columbus, OH 43210, United States. Electronic address: amanda.agnew@osumc.edu.
authors.forename: Amanda M
authors.initials: AM
authors.lastname: Agnew
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D012272:Ribs / Q000033:anatomy & histology / Q000502:physiology*; D012737:Sex Factors; D013314:Stress, Mechanical; D013909:Thorax / Q000502:physiology; D014947:Wounds and Injuries / Q000503:physiopathology; D055815:Young Adult
keywords: Energy; Force; Fracture; Stiffness; Thorax injury