Effect of Repeated Sterilization by Different Methods on Strength of Carbon Fiber Rods Used in External Fixator Systems

OBJECTIVES: We aimed to study the effects of repeated sterilization, using different methods, on the carbon fiber rods of external fixator systems. METHODS: We used a randomized set of 44 unused, unsterilized, and identical carbon fiber rods (11 × 200 mm), randomly assigned to 2 groups: unsterilized (4 rods) and sterilized (40 rods). The sterilized rods were divided into 2 groups, those sterilized in an autoclave and those sterilized using hydrogen peroxide. These were further divided into 5 subgroups based on the number of sterilization repetition to which the fibers were subjected (25, 50, 75, 100, and 200). A bending test was conducted to measure the maximum bending force, maximum deflection, flexural strength, maximum bending moment and bending rigidity. We also measured the surface roughness of the rods. RESULTS: An increase in the number of sterilization repetition led to a decrease in maximum bending force, maximum bending moment, flexural strength, and bending rigidity, but increased maximum deflection and surface roughness (P < 0.01). The effect of the number of sterilization repetition was more prominent in the hydrogen peroxide group. CONCLUSIONS: This study revealed that the sterilization method and number of sterilization repetition influence the strength of the carbon fiber rods. Increasing the number of sterilization repetition degrades the strength and roughness of the rods.