Effect of ultrasound on the strength of metal fixing pins for fractured bones

Abstract

Ultrasound is used successfully in traumatology and orthopedics to regulate the processes of reparative regeneration of injured bones [1-5]. In cases, however, where the fractured parts of an injured bone are adjusted and held in the correct position by metal fixing pins, the danger arises of a migration of the reinforcing constructions under the influence of mechanical oscillations. The ultrasound can also have a negative influence on the mechanical properties of the metal from which the fixing pin is made. 1Khl8N9T steel is most frequently used for this purpose. The combination of elements of which the steel is composed provides the predisposition for a labile austenitic structure. An increase in brittleness of the pin and a decrease in its mechanical strength disturb the stable fixation of the injured bone and lead to complications such as slow consolidation or the formation of a false joint. According to our sources these phenomena have not yet been studied. On the other hand, a solution of these problems is of great importance for practical medicine, which has stimulated us to carry out the present study.