A biomechanical analysis of the Ilizarov external fixator.

Five configurations of the Ilizarov fixator were analyzed in vitro. The overall stiffness, shear stiffness, and axial motion of the fracture site were determined. The data were compared with the results of eight conventional one-half frame fixators previously tested in the same manner. The Ilizarov fixator allowed significantly more axial motion at the fracture site during axial compression than the other fixators tested. The overall stiffness and shear rigidity of the Ilizarov external fixator were similar to those of the one-half pin fixators in bending and torsion. The stability of the Ilizarov fixator was a function of bone position within the fixator rings and fixation wire tension. The use of olive stop wires increased the shear resistance of the Ilizarov system.