Abstract
<title>Abstract</title> <p> <bold>Objective</bold> To systematically evaluate the accuracy of robot-assisted placement of various types of pelvic channel screws, compare the precision difference between short screws and trans-cortical screws, and analyze the influencing factors of screw malposition. <bold>Methods</bold> A retrospective analysis was conducted on 283 patients with pelvic fractures who underwent robot-assisted pelvic screw placement at Gansu Provincial Hospital from January 2021 to October 2025. There were 167 males and 116 females, with a mean age of (46.5±18.1) years. Patients were divided into eight groups according to screw type: S1 trans-cortical (33), S1 short (54), S2 trans-cortical (23), S2 short (39), antegrade anterior column (78), retrograde anterior column (67), antegrade LC-II (36), and retrograde LC-II (16). Screw accuracy was assessed by postoperative pelvic CT using the Smith grading system. The Chi-squared test or Fisher's exact test was used for group comparisons. <bold>Results</bold> The overall accuracy rate (Smith grade 0) was 98.6% (341/346). The combined accuracy of short screws (98.9%, 92/93) was significantly higher than that of trans-cortical screws (96.4%, 54/56, <italic>P</italic> =0.035). Univariate analysis revealed that screw type ( <italic>P</italic> =0.035) and BMI≥30 kg/m² (P=0.031) were associated with screw malposition, while age≥60 years ( <italic>P</italic> =0.639), sex ( <italic>P</italic> =0.556), and fracture type ( <italic>P</italic> =0.643) showed no significant association. All malpositioned screws were Smith grade I (cortical breach ≤2 mm). The excellent-good rate of Majeed score at 6 months postoperatively was 91.4% (85/93) in the short screw group and 85.7% (48/56) in the trans-cortical screw group ( <italic>P</italic> =0.097). <bold>Conclusion</bold> Robot-assisted pelvic channel screw placement demonstrates excellent overall accuracy. Short screws achieve significantly higher precision than trans-cortical screws, and BMI≥30 kg/m² is associated with an increased risk of malposition. When biomechanical fixation strength is satisfied, preferential use of short screws is recommended to reduce the risk of malposition, though larger prospective studies are needed for confirmation. </p>