A MECHANICAL EVALUATION OF THE RESISTANCE OF VARIOUS INTERFRAGMENTARYWIRE CONFIGURATIONS TO TORSION

Fourteen interfragmentary orthopedic wire configurations were tested i n torsion using a transverse fracture polyvinylchloride pipe model. Th ese models included single and double Kirschner pins with and without orthopedic wire added to the configuration. The orthopedic wire was ap plied in either an encircling, figure-of-eight (skewer pin), or crucia te pattern. Double Kirschner pins were applied in a mono- or biplanar fashion. An external fixator model was also tested. Stiffness, yield l oad, safe load, and energy of absorption were measured and calculated for each model. Orthopedic wire added to any configuration increased s tiffness. All single pin configurations with orthopedic wire and the e xternal fixator had the highest stiffness. Two Kirschner pins had a hi gher torsional yield load and safe load than single pin configurations with or without orthopedic wire. The external fixator model had the h ighest torsional yield load, safe load and energy of absorption of all configurations tested. However, the external fixator was only signifi cantly different in safe load from the 90 degrees biplanar configurati ons with wire and the cross pin configuration with encircling wire. Th e 90 degrees biplanar configurations with wire and the cross pin confi guration with encircling wire were equally as effective as the externa l fixator model in yield load and energy of absorption. (C)Copyright 1 996 by The American College of Veterinary Surgeons