title: Evaluation of strength at the acrylic-pin interface for variably treated external skeletal fixator pins.
abstract: OBJECTIVE
  To report pullout force to failure at the acrylic-pin interface for variably treated 3.2 mm external skeletal fixator pins.
  
  
  METHODS
  In vitro biomechanical evaluation.
  
  
  METHODS
  3.2 mm external skeletal fixator pins in polymethylmethacrylate bars.
  
  
  METHODS
  3.2 mm external skeletal fixator pins were used for each of 5 treatment groups: polished, unpolished, 3 notched, 5 notched, and machine knurled. Each pin was seated into a 2-cm-diameter acrylic connecting bar and tested in pullout force to failure. Each group consisted of 6 pins. The force required to remove the pins from the acrylic bar was measured and compared between groups.
  
  
  RESULTS
  Significant differences between treatment groups were determined (P<.05). Within a construct group failure mode was consistent. Fracture of the acrylic bar was only seen with knurled pin ends.
  
  
  CONCLUSIONS
  When using 2 cm acrylic bars in external skeletal fixation (ESF), a knurled pin shaft or a pin surface with 5 notches should be considered to improve the overall stability of the ESF construct.
authors.affiliation: Department of Small Animal Surgery, College of Veterinary Medicine and Biomedical Sciences, James L. Voss Veterinary Teaching Hospital, Colorado State University, Fort Collins, CO 80523, USA. jbcase@colostate.edu
authors.forename: Joseph
authors.initials: J
authors.lastname: Brad Case
authors.forename: Erick L
authors.initials: EL
authors.lastname: Egger
mesh_terms: D001696:Biomechanical Phenomena; D001858:Bone Nails; D004867:Equipment Design; D004868:Equipment Failure; D016267:External Fixators; D008422:Materials Testing; D019904:Polymethyl Methacrylate; D013314:Stress, Mechanical; D013718:Tensile Strength
chemical_list: D019904:Polymethyl Methacrylate