BACKGROUND: There is no consensus in the literature regarding the optimal treatment method for posterior pelvic ring injuries. This study aims to compare the radiologic and clinical outcomes, as well as complications of spinopelvic fixation (SPF) and iliosacral screw fixation (ISF) in patients with posterior pelvic ring injuries. METHODS: This retrospective study analyzed 54 patients (37 females, 17 males
mean age 38.9±18.7 years) with pelvic ring injuries classified as Tile type B and type C involving the posterior pelvic ring. These patients were treated with either SPF or ISF and followed for at least one year at two centers between 2016 and 2023. Of these, 28 patients comprised the SPF group, and 26 patients were in the ISF group. Comparisons were made regarding perioperative data (hemoglobin loss, blood product replacement, hospitalization duration, intensive care unit stay, surgery time, and fluoroscopy duration) and clinical outcomes (limb length discrepancy, Majeed score, visual analogue scale (VAS) score, and Short Form-36 (SF-36) score). Radiological outcomes were assessed using Matta outcome grading. Complications were also investigated. RESULTS: Hemoglobin loss (median 2.2 vs. 1 g/dL
p=0.027) and surgery time (67±10.6 vs. 37.7±11.3 minutes
p<
0.001) were higher in the SPF group, whereas fluoroscopy duration (median 2 vs. 51.5 seconds
p<
0.001) was higher in the ISF group. Other perioperative parameters did not differ between the groups. At a minimum follow-up of one year, clinical scores (Majeed score, VAS, SF-36), limb length discrepancy, and Matta outcome grades were similar between the groups. The SPF group had higher total complication rates (46.4% vs. 19.2%
p=0.034) and infection rates (42.9% vs. 3.8%
p<
0.001), while rates of neurological deficits, screw malposition, and other hospitalization complications (e.g., thromboembolic or cardiovascular events, pulmonary complications, sepsis) were not significantly different. CONCLUSION: Both spinopelvic fixation and iliosacral screw fixation techniques are similarly effective in terms of clinical and radiological outcomes, with both methods demonstrating a low rate of complications. However, SPF was associated with higher infection rates and greater hemoglobin loss, while ISF required increased fluoroscopy exposure.