[Biomechanical properties of external Ilizarov fixator with hybrid implants system]

Possible ways of improving the stability of the fragments of the femur under elongation by introducing hybrid implant systems (the Kirschner wires and the Schanz screws) into the Ilizarov fixator structure were explored. Experimental studies were conducted on physical models with the fixator mounted on a pipe section modelling the femur shaft. Ten modifications of the Ilizarov fixator were developed and tested. The designs differed in the kind and configuration of implants. The effect of the developed Ilizarov fixator designs was examined by comparing the coefficients of axial, transversal and torsional rigidity of the structures. The research results clearly show that the Ilizarov fixator's rigidity (particularly transverse rigidity) coefficients can be considerably increased by replacing the Kirschner wires with the Schanz screws or using hybrid systems of these implants. As a result, the stability of the femur fragments improves and so does the quality of the regenerated bone, which makes it possible to reduce the treatment time to a minimum.