Safe passage analysis for both column screw fixation technique in posterior column acetabular fractures

Both column screw fixation (BCSF) technique offers a novel minimally invasive approach for the management of acetabular posterior column fractures. A body of research has been established in this area, encompassing data on screw diameter, insertion angles, and even the feasibility of placing two screws. This study further investigates the anatomical feasibility of the BCSF technique (including composition of the pathway, the pathway area, the maximum permissible screw diameter, and the optimal insertion angles) through a 3D reconstruction study, providing an evidence-based foundation for its clinical application. In this study, pelvic CT data were collected from 200 healthy adults (100 males and 100 females). By utilizing Mimics 21.0 software, three-dimensional pelvic models were reconstructed to simulate the BCSF procedure for posterior column acetabular fractures. The maximum cross-sectional area of the pathway, the maximum allowable screw diameter, and the longest feasible screw length were all measured. In addition, the research analyzed the optimal screw insertion trajectories. An irregular three-dimensional configuration was displayed by the screw insertion safe zone. The pathway comprises a pentagonal structure. Quantitative analysis revealed that the left pelvis had a safe passage area of (132.1 ± 33.76 mm²), permitting screws with maximum dimensions of (145.57 ± 10.74 mm) in length and (8.92 ± 1.41) mm in diameter, while the right pelvis demonstrated slightly larger parameters (area: 139.66 ± 38.01 mm²; maximum screw length: 143.09 ± 10.47 mm; and diameter: 9.29 ± 1.47 mm). Compared to (36.89 ± 7.14°) and (41.89 ± 4.40°) for right-sided procedures, optimal insertion angles were measured at (37.32 ± 5.62°) centrolateral tilt and (42.55 ± 4.32°) cephalad tilt for left-sided approaches. Male specimens exhibited significantly greater safe passage dimensions than females (p < 0.0001), in which analogous sex-related differences were presented within maximum screw diameters and lengths. In contrast, cephalad tilt angles showed no statistically significant gender variation (p > 0.05). This study defines the anatomical safe zone for BCSF technique in posterior column acetabular fractures. The established optimal screw trajectory enhances fixation strength and fracture stability as it enables the clinical use of larger-diameter screws. The patient-specific three-dimensional preoperative planning is recommended to be performed, which can ensure precise screw placement and maximize surgical outcomes.