Low rates of pain requiring sacroiliac joint fusion after countersunk iliac screw for spinopelvic fixation

ABSTRACT Background: Iliac screws (IS) and sacral 2 alar-ISs are common methods for spinopelvic fixation but can result in symptomatic prominence or need for future sacroiliac (SI) joint fusion. A modification of the countersunk ISs technique includes a partial resection of the posterior superior iliac spine (PSIS) and countersinking of the screw head to minimize prominence. We investigate the need for surgical SI joint fusion and pain outcomes following the use of countersunk IS with partial resection of the PSIS. Methods: We identified patients from 2010 to 2024 who underwent spinopelvic fixation with countersunk IS with a minimum of 2 years follow-up. Variables collected included age, sex, body mass index (BMI), smoking status, SI joint fusion, IS site pain, construct infection, skin breakdown, IS revision due to pain or infection, and symptomatic screw prominence. Descriptive statistics were reported. Results: Five hundred and forty-six patients who underwent 1088 IS placements were included. The sample had a mean age of 64.5 years, was 65.3% female, and had a mean BMI of 28.3 kg/m 2 . There were no cases of SI joint fusion after IS fixation. IS site pain was noted in 27 (4.9%) patients, however, screw prominence on the physical exam was not observed. IS were revised or removed in 5 (0.9%) patients due to site pain unresponsive to nonsurgical treatment. Conclusion: We observed low rates of future surgical SI joint fusion for SI joint pain or reoperations due to IS prominence or screw-related pain with countersunk IS. Future comparative studies are necessary to support these conclusions.