Comparison of minimally invasive versus open spinopelvic fixation for unstable sacral fractures

Unstable sacral fractures represent complex injuries frequently associated with pelvic ring instability and high-energy trauma. Spinopelvic fixation provides the most stable construct for these fractures; however, the optimal surgical approach remains debated. This study aimed to compare the clinical and radiological outcomes of minimally invasive versus open spinopelvic fixation in the treatment of unstable sacral fractures.

A retrospective analysis of prospectively collected data was conducted, including 51 patients with vertically unstable sacral fractures operated on between 2014 and 2024. Twenty-seven patients underwent traditional open spinopelvic fixation (Group A), and twenty-four were treated using a minimally invasive technique (Group B). Demographic and perioperative parameters, fracture displacement, quality of reduction, intraoperative blood loss, radiation exposure, complications, length of hospital stay, and functional outcome (Majeed score) were analysed. Fracture reduction was assessed on postoperative CT (computed tomography) scans in axial and coronal planes. The relationship between functional outcome and maximum residual displacement was assessed using correlation analysis and displacement-stratified group comparisons. Statistical significance was set at p < 0.05.

No significant differences were found between the groups in age, sex, fracture type, mechanism of injury, or preoperative displacement. Operative time (157.7 ± 80.8 vs. 252.4 ± 83.8 min; p < 0.001) and intraoperative blood loss (180.4 ± 145.1 vs. 553.7 ± 285.9 ml; p < 0.001) were significantly lower in the minimally invasive group. Radiation exposure was higher in the minimally invasive group; however, the difference was not statistically significant (2391.7 vs. 2003.2 µGy/m²; p = 0.148). The quality of reduction did not differ significantly (p = 0.78), with excellent reduction achieved in 18/24 (75%) of minimally invasive and 19/27 (70%) of open cases. Postoperative infection occurred in 4 patients (7.8%), more frequently after open fixation (11% vs. 4.2%). The mean hospital stay was shorter following minimally invasive fixation (10.0 ± 9.7 vs. 12.6 ± 7.0 days; p = 0.045). The mean Majeed score was similar between the groups (89.97 ± 13.48 vs. 88.63 ± 9.22; p = 0.23). Stratification according to maximum residual displacement (≤ 5 mm, 5-10 mm, and > 10 mm) revealed no statistically significant differences in functional outcome (p = 0.34). Although no significant association was identified, a trend toward lower functional scores with increasing residual displacement was observed.

Minimally invasive spinopelvic fixation offers a comparable reduction quality and functional outcome to the open approach, while significantly reducing operative time, blood loss, and length of hospitalisation. This technique may be considered a valuable alternative for unstable sacral fractures in cases where closed reduction is achievable.