title: Bending characteristics of polymethylmethacrylate columns, connecting bars of carbon fiber, titanium, and stainless steel used in external skeletal fixation and an acrylic interface.
abstract: OBJECTIVE
  To (1) mechanically evaluate polymethylmethacrylate (PMMA) columns of various sizes and compare them to connecting bar materials (carbon fiber composite, titanium, stainless steel) and (2) compare the properties of an intact PMMA column to those of an acrylic interface.
  
  
  METHODS
  Experimental mechanical study.
  
  
  METHODS
  Experiment 1: 6 groups of 6 specimens each; experiment 2: 2 groups of 12 specimens each.
  
  
  METHODS
  All specimens were tested in 3-point bending. Stiffness, yield strength, and ultimate strength values were calculated for each specimen.
  
  
  RESULTS
  PMMA 1 columns (23.25 mm) compared favorably to titanium or stainless-steel bars. PMMA 3 columns (30.15 mm) and carbon fiber bars had similar yield strength but PMMA 3 columns were less stiff than carbon fiber bars. PMMA 3 columns had lower bending modulus and a higher variability in their mechanical properties than PMMA 1 or PMMA 2 (25.64 mm) columns. Acrylic interface specimens were less strong but as stiff as intact specimens.
  
  
  CONCLUSIONS
  An acrylic interface was easily created and had acceptable biomechanical characteristics.
  
  
  CONCLUSIONS
  PMMA 2 and PMMA 3 columns are not recommended for clinical use at this time. Further tests are needed to analyze an acrylic patch in a more clinically relevant loading model.
authors.affiliation: Department of Clinical Sciences, Colorado State University, Fort Collins, CO, USA. pierreamsellem@hotmail.com
authors.forename: Pierre M
authors.initials: PM
authors.lastname: Amsellem
authors.forename: Erick L
authors.initials: EL
authors.lastname: Egger
authors.forename: Daniel L
authors.initials: DL
authors.lastname: Wilson
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D002244:Carbon / Q000592:standards; D000077482:Carbon Fiber; D019245:Compressive Strength; D016267:External Fixators / Q000662:veterinary*; D005592:Fracture Fixation / Q000295:instrumentation / Q000662:veterinary*; D019904:Polymethyl Methacrylate / Q000592:standards; D013193:Stainless Steel / Q000592:standards; D013314:Stress, Mechanical; D013718:Tensile Strength; D014025:Titanium / Q000592:standards; D054159:Torsion, Mechanical
chemical_list: D000077482:Carbon Fiber; D013193:Stainless Steel; D002244:Carbon; D019904:Polymethyl Methacrylate; D014025:Titanium