Experimental study of mechanical properties of composite carbon screws.

Carbon-carbon composite was used to manufacture carbon screws as possible material for osteosynthesis. The mechanical properties were optimized including the fibre orientation in the composite volume, the effect of the size of the thread and the thread shape. The mechanical properties of the carbon screws were compared with conventional OSTEO steel cortical screws. Two types of carbon specimens were used, varying in fibre orientation along the screw axis. The mechanical properties of the carbon screws including the failure force for one thread and the critical shear stress were determined. The force destroying the connection of the carbon screw with bone was determined. The holding capacity of the carbon screw was compared to the steel screw. The extraction tests demonstrated 50% less holding force than the OSTEO steel screw.