High speed insertion of bone fracture fixation pins: a finite element penetration model with experimental comparisons

J Mater Sci Mater Med. 2011 Dec;22(12):2823-32. doi: 10.1007/s10856-011-4461-x. Epub 2011 Nov 1.

Abstract

A new method of bone fracture fixation is considered in which small pins/darts are dynamically inserted into bone to prevent translation and rotation at the fracture site. An ABAQUS model was developed to analyze dart penetration in cortical and cancellous bone for varying dart diameter, material, and velocity, and cortical thickness. The method is advocated for bioresorbable darts, so polylactide (PLA) and magnesium are the materials examined in this study. Numerical results showed that magnesium darts can achieve full penetration in bone while suffering little damage. The PLA darts penetrated thin bone well, but substantial deformation was seen as the cortical thickness increased, especially for small diameter darts. As partial validation, prototype PLA fixation darts were fired into cadaveric bone with a custom nailer. As in the model, the PLA darts could penetrate thin cortices but saw gross deformation when impacted against thicker bone.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Bone Nails
  • Bone and Bones / metabolism
  • Cadaver
  • Computer Simulation
  • Equipment Design
  • Finite Element Analysis
  • Fracture Fixation, Internal / methods*
  • Humans
  • Internal Fixators
  • Magnesium / chemistry*
  • Materials Testing
  • Polyesters / chemistry*
  • Stress, Mechanical

Substances

  • Polyesters
  • poly(lactide)
  • Magnesium