Influence of pins configuration to balance of general transversal stability in long bone fractures external fixation

Biomechanical features of long bones indicate that external fixation of long bone fractures have to be balanced according to general transversal stability as more as possible. The aim of this work was to investigate the influence of orientation pins to the general transversal stability of external fixation of fractures of long bones. In this study we have used the model of fractured long bone made of wood which was treated by Mitkovic external fixator with 4 pins, in 3 different situations: (1) all pins are in one axial plane, (2) each 2 pins are in 2 axial planes with angle distances of 60 degrees, (3) each 2 pins are in 2 axial planes wich are normal to each other. Means of relations of measured movements of long bone model fragments during the use of perpendicular force from 2 directions, normal to each other, after grouping of results in 3 grous: 0.17, 0.46 and 0.72. Statistical analyses showed that the differences between each of 3 grous were significant (p < 0.05). It can be concluded that it is better if pins are oriented in different axial planes, with pretension that both planes are normal to each other, during external fixation of long bone fractures.