Finite element analysis of the stability of transverse acetabular fractures in standing and sitting positions by different fixation options.

Background: Treatment of a transverse acetabular fracture type is possible from an anterior approach, a posterior approach or both. Different fixation methods have been described but whether one is superior to the other is still under debate. The aim of the current study was to test the different fixation alternatives of stabilization of transverse acetabular fractures under two basic physiological loading conditions: standing and sitting utilizing a finite element model.

Material And Methods: A transtectal transverse fracture model was fixed in five different alternatives: an anterior column plate; a posterior column plate; an anterior column plate combined with a posterior column screw; a posterior column plate combined with an anterior column screw; and a posterior column plate and an anterior column plate. In these models, a load of 400N was applied at standing and sitting positions and the displacements were analyzed by using three-dimensional finite element stress analysis method.

Results: In the model simulating standing human position, overall motion at the posterior column was minimum when two columns were plated (0.071mm). The second best fixation was posterior column plate with an anterior column screw (0.077mm). Overall motion at the anterior column was minimum by posterior column plate with an anterior column screw (0.0326mm). The plating of two columns was associated with motion of (0.0333mm). In the model that simulates sitting position, the motion at the posterior column was minimum when two columns were plated (0.0478mm), and (0.0517mm) when a posterior column plate with an anterior column screw was used. Overall motion in the anterior column was minimum when posterior column plate with an anterior column screw (0.0198mm) was used, whereas the motion was (0.0203mm) when plating of both columns was examined.

Conclusion: Posterior column plating combined with an anterior column screw has quite comparable results to a both column plating in transverse fractures, suggesting that two column fixations might be unnecessary. This method is also very superior to anterior column plating combined with a posterior column screw in that type of fractures.