title: Short term in vivo precision of proximal femoral finite element modeling.
abstract: As more therapies are introduced to treat osteoporosis, precise in vivo methods are needed to monitor response to therapy and to estimate the gains in bone strength that result from treatment. A method for evaluating the strength of the proximal femur was developed and its short term reproducibility, or precision, was determined in vivo. Ten volunteer subjects aged 51-62 years (mean 55.6 years), eight women and two men, were examined using a quantitative computed tomography (QCT) protocol. They were positioned, scanned, repositioned and re-scanned. The QCT images were registered in three-dimensional space, and finite element (FE) models were generated and processed to simulate a stance phase load configuration. Stiffness was computed from each FE model, and strength was computed using a regression equation between FE stiffness and fracture load for a small set (n = 6) of experimental specimens. The coefficients of variation (COV) and repeatability (COR= 2.23* 42*COV) were determined. The COV for the FE fracture load computed was 1.85%, and the detectable limit (coefficient of repeatability) for serial measurements was 5.85%. That is, if a change of 5.85% or more in computed FE fracture load is observed, it will be too large to be consistent with measurement variation, but instead can be interpreted as a real change in the strength of the bone. The detectable limit of this method makes it suitable for serial research studies on changes in femoral bone strength in vivo.
authors.affiliation: Diagnostic Radiology, Henry Ford Hospital, Detroit, MI, 48202, USA. dianna@rad,hfh.edu
authors.forename: D D
authors.initials: DD
authors.lastname: Cody
authors.forename: F J
authors.initials: FJ
authors.lastname: Hou
authors.forename: G W
authors.initials: GW
authors.lastname: Divine
authors.forename: D P
authors.initials: DP
authors.lastname: Fyhrie
mesh_terms: D001696:Biomechanical Phenomena; D001698:Biomedical Engineering; D005260:Female; D005269:Femur / Q000033:anatomy & histology / Q000502:physiology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D015203:Reproducibility of Results