title: Quantifying the Effects of Formalin Fixation on the Mechanical Properties of Cortical Bone Using Beam Theory and Optimization Methodology With Specimen-Specific Finite Element Models.
abstract: The effects of formalin fixation on bone material properties remain debatable. In this study, we collected 36 fresh-frozen cuboid-shaped cortical specimens from five male bovine femurs and immersed half of the specimens into 4% formalin fixation liquid for 30 days. We then conducted three-point bending tests and used both beam theory method and an optimization method combined with specimen-specific finite element (FE) models to identify material parameters. Through the optimization FE method, the formalin-fixed bones showed a significantly lower Young's modulus (-12%) compared to the fresh-frozen specimens, while no difference was observed using the beam theory method. Meanwhile, both the optimization FE and beam theory methods revealed higher effective failure strains for formalin-fixed bones compared to fresh-frozen ones (52% higher through the optimization FE method and 84% higher through the beam theory method). Hence, we conclude that the formalin fixation has a significant effect on bovine cortical bones at small, elastic, as well as large, plastic deformations.
authors.forename: Guan-Jun
authors.initials: GJ
authors.lastname: Zhang
authors.forename: Jie
authors.initials: J
authors.lastname: Yang
authors.forename: Feng-Jiao
authors.initials: FJ
authors.lastname: Guan
authors.forename: Dan
authors.initials: D
authors.lastname: Chen
authors.forename: Na
authors.initials: N
authors.lastname: Li
authors.forename: Libo
authors.initials: L
authors.lastname: Cao
authors.forename: Haojie
authors.initials: H
authors.lastname: Mao
mesh_terms: D000818:Animals; D002417:Cattle; D019245:Compressive Strength / Q000502:physiology; D003198:Computer Simulation; D000071538:Cortical Bone / Q000737:chemistry* / Q000502:physiology*; D055119:Elastic Modulus / Q000502:physiology; D005269:Femur / Q000737:chemistry* / Q000502:physiology*; D020342:Finite Element Analysis; D005404:Fixatives / Q000737:chemistry; D005557:Formaldehyde / Q000737:chemistry*; D066298:In Vitro Techniques; D008297:Male; D008954:Models, Biological; D013314:Stress, Mechanical; D013718:Tensile Strength / Q000502:physiology
chemical_list: D005404:Fixatives; D005557:Formaldehyde