Medical Student The Ohio State University College of Medicine
Disclosure(s):
Lin Abigail Tan, BS: No financial relationships to disclose
Introduction: Adult spinal deformity (ASD) is a devastating condition with a significant disease burden, affecting up to 68% of the elderly population. Long-segment spinal fusions are a common treatment, though initial techniques were complicated by pseudoarthrosis. The subsequent development of pelvic instrumentation has decreased these complications, though there is still little known regarding the differences between various methods. This study aimed to compare the clinical and radiographic outcomes between two types of pelvic instrumentation, sacro-alar-iliac (SAI) and iliac screws.
Methods: We performed a retrospective review of adult long-segment fusions utilizing CPT 22848 billing codes from 2017-2019. Demographic and surgical data included age, sex, BMI, ASA class, osteoporosis, diabetes, interbody fusion type, levels fused, anesthesia time, estimated blood loss, O-arm use, BMP use, fluoroscopy time, and postoperative complications. Radiographic data included lumbar lordosis, implant failures, removals, and rates of reoperation. Failures were categorized as rod fractures, screw loosening, sacral/body fracture, or cap disengagement.
Results: Of the 198 identified patients, 154 were included for final analysis, with 75 (51.3%) patients receiving iliac and 79 (48.7%) patients receiving SAI screws. Baseline demographics and preoperative spinopelvic parameters were similar between cohorts, aside from patient age (65.9 iliac versus 60.2 SAI, p < 0.001). SAI in this cohort were associated with longer anesthesia time (726 versus 592 minutes, p < 0.001) and greater blood loss (4152 versus 2034 mL, p < 0.001). Iliac screws were associated with more O-arm verification (32.5% versus 0%, p < 0.001). Instrumentation failure was greater in the SAI cohort (20.4% and 11.2%, p = 0.020), with multivariate analysis corroborating these findings and risk of instrumentation failure in the traditional iliac group being less than half of those in the SAI group (OR: 0.435, 95% CI 0.215-0.882, p = 0.020).
Conclusion : SAI fixation was associated with higher rates of instrumentation failure compared to iliac fixation. However, there was no difference in rates of complications and reoperation, and reoperation for iliac screw removal was not examined. Further prospective, randomized studies are necessary to discern differences and identify an ideal method of pelvic instrumentation.