Bending characteristics of polymethylmethacrylate columns, connecting bars of carbon fiber, titanium, and stainless steel used in external skeletal fixation and an acrylic interface.
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.
Amsellem
Pierre M
PM
Department of Clinical Sciences, Colorado State University, Fort Collins, CO, USA. pierreamsellem@hotmail.com
Egger
Erick L
EL
Wilson
Daniel L
DL
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
D000077482:Carbon Fiber; D013193:Stainless Steel; D002244:Carbon; D019904:Polymethyl Methacrylate; D014025:Titanium