Definition of a safe zone for screw fixation of posterior talar process fracture by 3-dimensional technology

Background: Percutaneous screw fixation can provide stable fixation with a minimally invasive surgical technique for posterior talar process fracture. Objectives: The purpose of this study was to investigate the optimal posterior screw placement and the geometry of safe zone for screw insertion in the posterior talar process by analyzing with 3-dimensional (3D) technology. Methods: 100 adult feet computed tomography (CT) scans were evaluated. CT data were imported into Materiaise's interactive medical image control system (MIMICS) 18.01 software for 3-dimensional reconstruction. Two 3.0mm-diameter screws were simulated from the posterior to anterior position for posterior talar process. The morphology parameters of posterior talar process were also quantitatively measured. The safe zone and the length and entry point of screw were defined. Results: The optimal entry point of screw for posterior talar process fracture was lateral tubercle from the posterior to anterior position. The safe zone of medial tubercle entry point was smaller in lateral tubercle. These gender-specific measurements were all significant (P<.001). Conclusions: The predefined zone with computer-assisted 3D techniques for the most frequently positioned percutaneous screws may aid in preoperative planning, shorten the operation time and reduce the incidence of surgical complications.