A biomechanical evaluation of different fixation strategies for posterolateral fragments in tibial plateau fractures and introduction of the 'magic screw'.

BACKGROUND

Posterior plate fixation is biomechanically the strongest fixation method for posterolateral column fracture (PLCF) of the tibial plateau; however, there are inherent deficiencies and risks of a posterior approach. Thus, the 'magic screw' was proposed to enhance fixation stability of the lateral rafting plate used for PLCF. The purpose of this study was to re-examine and compare the stability of different fixation methods for PLCF.

METHODS

Synthetic tibiae models were used to simulate posterolateral split fractures. The fracture models were randomly assigned into three groups: Group A, fixed with posterolateral buttress plates; Group B, with lateral locking compression plates (LCP); and Group C fixed with lateral LCPs and one 'magic screw'. Gradually increased axial compressive loads were applied to each specimen.

RESULTS

There was a mean subsidence hierarchy of the posterolateral fragment at different load levels: Group A had the least subsidence, followed by Group C, and Group B had the most. There were no significant differences in the mean loads at different displacements between Group A and Group C. Group A had the highest axial stiffness. Additionally, there was a significant difference in axial stiffness between Group B and Group C.

CONCLUSION

Biomechanical stability of the combined fixation of the posteriorly positioned lateral rafting plate with the 'magic screw' was much closer to that of posterior plate fixation for split-type PLCF. The necessity of posterior fixation through a posterior approach may be reduced for selected patients.