Biomechanical study on osteotomized tibias fixed with unilateral adjustable external fixator.

Five fresh tibias removed from 30-40 years old dead males were osteotomized at one-third supra-medium segment and then fixed by an unilateral adjustable external fixator (UAEF) to be used as a model of external fixation of tibial fracture. For each loading test under different configurations of UAEF, the ratio of the force-displacement was used to determine its stiffness value. The weakest mode of the UAEF device is in AP bending. Under each mode of compression, distraction, anteroposterial and lateral bending and torsion loading, increasing the pin number or pin diameter or pin separation, and/or reduction of pin group separation can significantly increase the stiffness values of UAEF (P < 0.01). These data revealed that UAEF is suitable for the external fixation of tibial fracture.