Re-design of a uniplanar, monolateral external fixator

Proc Inst Mech Eng H. 2018 May;232(5):446-457. doi: 10.1177/0954411918762021. Epub 2018 Mar 9.

Abstract

This work deals with the structural analysis of screw clamps for external fixator devices. Screw clamps are widely used in external fixators as a means to connect the half-pins to the fixator body. The analysis is carried out by both numerical and experimental techniques, based on the case study of a clamp produced by Citieffe (Bologna, Italy). As a preliminary activity, the tribological parameters involved in the screw-clamp interaction have been characterized by means of a mixed finite element analysis and experimental procedure. Then, an assessment of the current design of the clamp has been carried out. A re-design has been proposed, which, based on some targeted geometrical modifications, allows achieving higher strength requirements with the same overall dimensions and type of materials. A higher load-bearing capability for a given size may allow the fixator to be used on a broader population. Finally, a list of good practices for the design of this kind of clamps has been proposed.

Keywords: Friction measurement/testing; external fixator; finite element; screw clamp; stress analysis/testing; tribology of machine elements.

MeSH terms

  • Equipment Design
  • External Fixators*
  • Fractures, Bone / surgery
  • Friction
  • Humans
  • Mechanical Phenomena