Geriatric Type II Fractures of the Dens Axis: Biomechanical Superiority of a New Osteosynthesis Plate Compared to Common Anterior Screw Fixation.

Study DesignBiomechanical Basic Research.ObjectivesType II Fractures of the dens axis (DFTII) are common fractures of the cervical spine in geriatric patients. A surgical approach is the anterior screw fixation (ASF). However, a disadvantage is the high post-operative rate of non-union. This study aimed to develop and biomechanically test an osteosynthesis plate (OSP) for the anterior treatment of DFTII in comparison to ASF.MethodsA novel OSP was developed and manufactured. The OSP was biomechanically tested in comparison to ASF in synthetic bone models and geriatric human cadaveric bone. An analysis of the bone microstructure of the human C2 vertebrae was performed utilizing high-resolution quantitative computed tomography to exclude differences in bone quality among the experimental groups. Biomechanical testing was performed by cyclic loading of compression and tensile forces until failure.ResultsIn the comparative biomechanical analysis of ASF and OSP in synthetic bone, significant differences were observed regarding the load to failure, favoring the OSP (P = 0.040). The comparative biomechanical analysis of ASF and OSP in the cadaveric specimens also revealed a significantly lower load to failure of the ASF (P = 0.046). The experimental groups did not show significant differences regarding age, sex or bone microstructure.ConclusionsThe current study demonstrated that the OSP is biomechanically superior to the ASF, indicating higher stability. This study provides the basis for an alternative anterior treatment option for DFTII.