title: Heterogeneity in skeletal load adaptation points to a role for modeling in the pathogenesis of osteoporotic fracture.
abstract: Genetic, environmental, or hormonal factors may cause heterogeneity in skeletal load response. Individuals with reduced sensitivity to load should require higher strains to generate an adaptive response, consequently have weaker bones and fracture more frequently. The purpose of our study was to determine if stresses (proportional to strains) at the femoral neck under equivalent loads were higher in women with a history of fractures compared with women without fractures. We studied postmenopausal women participating in the Canadian Multicentre Osteoporosis Study who had available hip structure analysis data from dual-energy X-ray absorptiometry scans (n = 2168). Women were categorized into 2 groups based on their number of self-reported fractures. We computed stress (megapascals) at the inferomedial margin of the femoral neck in a one-legged stance mode using a 2-dimensional engineering beam analysis. We used linear regression (SAS 9.3) to determine associations between stress, geometry parameters, and number of fractures. Postmenopausal women with 1 or more fractures had higher stress (2.6%), lower narrow neck bone mineral density (4.2%), cross-sectional area (3.9%), and section modulus (9.6%) than postmenopausal women without fractures (all p < 0.05). These findings provide evidence of heterogeneity in load response and suggest an important role for modeling in the pathogenesis of osteoporotic fracture.
authors.affiliation: Multidisciplinary Osteoporosis Research Program, Women's College Hospital, Toronto, ON, Canada; Department of Exercise Sciences, University of Toronto, Toronto, ON, Canada. Electronic address: celeste.hamilton@utoronto.ca.
authors.forename: Celeste J
authors.initials: CJ
authors.lastname: Hamilton
authors.affiliation: Multidisciplinary Osteoporosis Research Program, Women's College Hospital, Toronto, ON, Canada; Department of Medicine, University of Toronto, Toronto, ON, Canada.
authors.forename: Sophie A
authors.initials: SA
authors.lastname: Jamal
authors.affiliation: Beck Radiological Innovations Inc., UMBC Technology Incubator, Halethorpe, MD, USA.
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Beck
authors.affiliation: Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, MD, USA.
authors.forename: Alia S
authors.initials: AS
authors.lastname: Khaled
authors.affiliation: Department of Medicine, St. Joseph's Healthcare/McMaster University, Hamilton, ON, Canada.
authors.forename: Jonathan D
authors.initials: JD
authors.lastname: Adachi
authors.affiliation: Centre de Recherche du Centre Hospitalier Universitaire de Québec (CHUQ), Centre Hospitalier de l'Université Laval (CHUL), Québec, QC, Canada.
authors.forename: Jacques P
authors.initials: JP
authors.lastname: Brown
authors.affiliation: A Priori Medical Sciences Inc., Victoria, BC, Canada.
authors.forename: Kenneth S
authors.initials: KS
authors.lastname: Davison
mesh_terms: D015502:Absorptiometry, Photon; D000222:Adaptation, Physiological / Q000502:physiology*; D000367:Age Factors; D000368:Aged; D015519:Bone Density; D002170:Canada; D016022:Case-Control Studies; D015331:Cohort Studies; D005260:Female; D005272:Femur Neck / Q000503:physiopathology*; D006801:Humans; D008875:Middle Aged; D058866:Osteoporotic Fractures / Q000209:etiology*; D012307:Risk Factors; D013314:Stress, Mechanical; D016474:Weight-Bearing / Q000502:physiology
keywords: Femur; fracture; mechanical load; postmenopausal; stress