Comparative study of transpedicular screw fixation for the resistance to axial elongation

The results of trials for the resistance of a modified transpedicular screw to axial elongation were evaluated in comparison with series-production specimens. Anatomical samples of human vertebrae and monoaxial transpedicular screws were prepared for the experiment, and they constituted one main group and two control ones. The screws were implanted according to the generally accepted technique with x-ray controlling the screw position in the vertebra. The study was performed on the basis of the laboratory of the Institute of Metal Superplasticity Problems of Russian Academy of Sciences (the town of Ufa) using INSTRON 1185 (England) testing machine. The values of maximal resistance of the transpedicular screws to axial elongation were within the limits of 1100- 1250 Newtons, but after reaching the peak values the resistance of the main group screws was more statically reliable than that in control groups. The construction modification of the transpedicular screw positively influenced its fixation potentials (resistance to axial elongation) in the vertebra.