Comparison of mechanical performance among different frame configurations of the Ilizarov external fixator: experimental study.

The circular frame of the Ilizarov fixator can be modified to reflect anatomic variations and treatment aims. However, these modifications in the frame system cannot always achieve the mechanical performance of the standard frame system. A standard system has two rings in each bone fragment connected by four longitudinal bars on each side of the ring. In this study, the mechanical performances of one standard and eight modified frame systems were compared. Each system was loaded on a material testing machine, with calculation of axial compression, four-point bending, and torsion. As a result, systems that were modified with drop wires and Schanz screws 45 degrees oblique to the wires on the proximal ring provided a mechanical performance closer to the standard system than systems with other modifications.