Evaluation of filler materials used for uniform load distribution at boundaries during structural biomechanical testing of whole vertebrae

Do Gyoon Kim, X. Neil Dong, Ting Cao, Kevin C. Baker, Richard R. Shaffer, David P Fyhrie, Yener N. Yeni

Research output: Contribution to journalArticle

18 Scopus citations

Abstract

This study was designed to compare the compressive mechanical properties of filler materials, Wood's metal, dental stone, and polymethylmethacrylate (PMMA), which are widely used for performing structural testing of whole vertebrae. The effect of strain rate and specimen size on the mechanical properties of the filler materials was examined using standardized specimens and mechanical testing. Because Wood's metal can be reused after remelting, the effect of remelting on the mechanical properties was tested by comparing them before and after remelting. Finite element (FE) models were built to simulate the effect affilier material size and properties on the stiffness of vertebral body construct in compression. Modulus, yield strain, and yield strength were not different between batches (melt-remelt) of Wood's metal. Strain rate had no effect on the modulus of Wood's metal, however, Young's modulus decreased with increasing strain rate in dental stone whereas increased in PMMA. Both Wood's metal and dental stone were significantly suffer than PMMA (12.7 ± 1.8 GPa, 10.4 ± 3.4 GPa, and 2.9 ± 0.4 GPa, respectively). PMMA had greater yield strength than Wood's metal (62.9 ± 8.7 MPa and 26.2 ± 2.6 MPa). All materials exhibited size-dependent modulus values. The FE results indicated that filler materials, if not accounted for, could cause more than 9% variation in vertebral body stiffness. We conclude that Wood's metal is a superior moldable bonding material for biomechanical testing of whole bones, especially whole vertebrae, compared to the other candidate materials.

Original languageEnglish (US)
Pages (from-to)161-165
Number of pages5
JournalJournal of Biomechanical Engineering
Volume128
Issue number1
DOIs
StatePublished - Feb 2006
Externally publishedYes

Keywords

  • Dental cement
  • Finite element modeling
  • Mechanical property
  • Mechanical testing
  • Polymethyl-methacrylate
  • Spine biomechanics
  • Vertebra
  • Viscoelasticity
  • Wood's alloy

ASJC Scopus subject areas

  • Biomedical Engineering
  • Biophysics

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