title: An investigation of the bending stiffness of and the plane stresses generated by a flanged external fixator pin.
abstract: In an attempt to reduce pin loosening, a flanged external fixator pin has been designed and its bending stiffness has been compared with that of a standard pin. The pins were inserted into pilot holes previously drilled into a piece of teak hardwood. Loads of different magnitudes were applied at a fixed moment arm and force-deflection curves were obtained. Thereafter, percentage stiffness increase was calculated for each pilot hole size. The results show that the addition of a collar to the external fixator pin increases its stiffness and its ability to resist bending forces. In a parallel study, the stresses generated at the pin-bone interface by this pin and a standard pin were compared using finite element analysis techniques. The results show that the flange significantly reduced the stresses generated at the pin-bone interface. In addition, stresses were dissipated over a wider area.
authors.affiliation: Department of Orthopaedic Surgery, Glenfield General Hospital, Leicester, England.
authors.forename: O O
authors.initials: OO
authors.lastname: Oni
authors.forename: M
authors.initials: M
authors.lastname: Capper
authors.forename: C
authors.initials: C
authors.lastname: Soutis
mesh_terms: D001696:Biomechanical Phenomena; D001858:Bone Nails; D016267:External Fixators; D008962:Models, Theoretical; D013314:Stress, Mechanical