Experimental Validation of Transpedicular Fixation System Modification

Abstract

Objective. To compare the strength resistance of seriesproduced and modified spinal systems to continuous cyclic loading. Material and Methods. Assembled transpedicular four-screw systems with monoaxial screws of equal configuration were tested. The study group included modified fixation system, and the control group -series-produced domestic fixation systems. All devices were fixed in textolite vertebra models with the account for average pedicle angle and interpedicular distance, with equal interval between vertebrae, and using one transverse connector. The models were exposed to axial cyclic loading. Results. In dynamic loading conditions with 150 kg load (1,500 Newton) and the frequency of 6 cycles per second, the maximum strength of transpedicular fixation system from the study group was at average statistically reliably 22.1 % higher than that from the control group (p ≤ 0,05). Conclusion. The performed study appeared to be a scientific rationale for transpedicular screw modification. Suggested modification statistically reliably increases the maximum strength of fixation system, which reduces complication rate after transpedicular fixation and allows extending indications for transpedicular spinal fusion alone.