The biomechanical performance of the both-column screw in posterior acetabular column fractures

The both column screw (BCS) fixation technique has been described as a fixation method for acetabular posterior column fractures. This study aimed to biomechanically evaluate and compare different fixation strategies for acetabular posterior column fractures, including BCS-based, plate-based, and hybrid (BCS + P) constructs, using finite element analysis (FEA) METHODS: Within the scope of FEA, five different internal fixation models were constructed: fixation using a single BCS (sBCS), double BCS (dBCS), a single plate (sP), double plates (dP), and a combination of one BCS and one plate (BCS+P). During the modeling process, mesh generation was performed, material properties were assigned, and boundary and contact conditions were defined. All models were subjected to three physiological loading conditions: level walking, stairs up, and stairs down. Outcomes were evaluated in terms of stress on the screw, stress on the bone, total deformation, fracture gap, and sliding distance in fracture surface.

Biomechanical differences were observed among the five models. The sP model demonstrated the highest deformation and fracture gap values under all loading conditions, indicating inferior biomechanical performance. In contrast, the sBCS and dP models showed lower deformation values and generally more favorable fracture stability. The BCS + P model exhibited variable performance, particularly in terms of fracture gap and sliding distance across different loading conditions. Among all configurations, the dBCS model achieved the most favorable biomechanical performance, with the lowest deformation and fracture displacement values.

The both column screw fixation technique, particularly in a double-screw configuration, provides sufficient stability for posterior column fracture fixation and may represent a viable alternative to plate-based strategies, offering an additional and stable fixation option that may expand the surgical armamentarium.