The biomechanical study of different fixation techniques for combination fractures of atlas and axis: a finite element analysis.

Combination atlas-axis fractures are less studied but relatively common with a higher incidence of neurological deficits than isolated C1 or C2 fractures. Several authors focused on the treatment strategies, but there is no study to compare the stability of different fixation methods; neither not yet clear which technique represents the best choice and whether stabilization devices can be efficient and beneficial for complex atlantoaxial fractures. The aim of this study was to compare the biomechanical properties of three fixation techniques: atlantoaxial pedicle screws fixation (PSF), occipital-cervical fusion (OCF) and transarticular screw fixation (TSF) based on combination factures model. Our results showed the range of motion (ROM) of fracture model increased obviously than intact model. The ROM in flexion/extension and rotation of C0-C1 in PSF and TSF models were increased. The ROM of C1-C2 in all conditions in PSF, OCF and TSF models were decreased. The ROM of C2-C3 was decreased in OCF, but remains the same stage in PSF and TSF. These suggested that three surgical methods are effective for the combination fractures of atlas and axis, which can ensure good stability. It can properly increase the ROM of C0-C1 when using PSF. These findings would aid in the treatment of this complex fractures.