Abstract:[Objective] To explore the clinical value of using 3D printed guide to assist sacroiliac screw fixation in the treatment of pelvic posterior ring injury. [Method] A retrospective analysis was conducted on the clinical data of 45 patients with pelvic posterior ring injury admitted to the trauma orthopedic ward center of our hospital from January 2020 to February 2023. Based on preoperative doctor-patient communication results, 21 patients were assisted with 3D guide, while 24 patients were treated with screw placement by freehand technique. The perioperative, follow-up, and imaging data were compared between the two groups. [Results] The 3D group proved significantly superior to the freehand group in terms of surgical time [(84.8±2.6) min vs (113.3±2.2) min, P＜0.001], screw insertion time [(40.9±0.4) min vs (65.3±1.6) min, P＜0.001], number of screw adjustments [(0.8±0.7) times vs (4.0±0.9) times, P＜0.001], and X-ray exposure time [(35.2± 0.8) s vs (77.3±1.4) s, P＜0.001]. The average follow-up period lasted for (24.1±7.5) months, and the 3D group resumed full weight-bearing activity significantly earlier than the freehand group [(85.6±2.7) days vs (95.1±0.6) days, P=0.046]. Compared with those one month after surgery, both groups of patients showed significant improvements in VAS score, hip extension and flexion, internal-external rotation ROM, and Majeed score at the last follow-up (P＜0.05). The 3D group proved significantly better than the freehand group in terms of VAS score [(2.6±0.3) vs (3.7±0.2), P=0.042], hip extension flexion ROM [(121.2±1.1)° vs (103.2±1.6)°, P=0.046], hip internal and external rotation ROM [(78.0±0.5)° vs (55.5±0.9)°, P＜0.001], and Majeed score [(36.5±2.3) vs (26.8±0.3), P＜0.001] 1 month postoperatively, whereas the differences in aforesaid items became not significant between the two groups since then (P＞0.05). Radiographically, the 3D group was also significantly better than the freehand group in terms of accuracy of screw placement [cases (%)] [excellent/good/poor, 19 (90.4) / 1 (4.8) / 1 (4.8) vs 14 (58.3) / 7 (29.2) / 3 (12.5), P＜0.001], fracture reduction quality [excellent/good/poor, 18 (85.7) / 2 (9.5) / 1 (4.8) vs 11 (45.8) / 9 (37.5) / 4 (16.7), P＜0.001], and fracture healing time [＜10 weeks / 10~16 weeks / ≥ 16 weeks, 17 (80.9) / 3 (14.3) / 1 (4.8) vs 11 (45.8) / 10 (41.7) / 3 (12.5), P＜0.001]. [Conclusion] The 3D printed guide assisted sacroiliac screw fixation for pelvic posterior ring fractures has minimal damage and can achieve better early treatment outcomes.