Abstract
Introduction: Pelvic fixation is standard in adult spinal deformity (ASD) surgery constructs which span the lumbosacral junction, yet distal mechanical failure and sacroiliac joint (SIJ) pain remain problematic. Adjunctive SIJ fusion is increasingly used to address these issues, but data on its safety and outcomes are limited. Methods: We performed a retrospective review of a prospectively maintained single-institution ASD database. Consecutive patients over 18 years of age undergoing elective long-segment reconstruction (≥4 levels) with multipoint pelvic fixation (MPF), defined as ≥2 fixation points on a side, and open posterior SIJ fusion during the index surgery were included. Baseline demographics, preoperative SIJ pain (posterior superior iliac spine pain ≥4/10), and Oswestry Disability Index (ODI) were recorded. One-year clinical and radiographic outcomes were assessed, including spinopelvic alignment, persistence of SIJ pain, mechanical integrity of pelvic instrumentation, and lumbosacral fusion grading on CT when available. Results: Sixty-one patients met inclusion criteria. All had radiographic follow-up, with 39 (64 %) completing 1-year imaging and 49 (80 %) clinical follow-up (mean 0.97 years). Mean age was 66.2 years and 69 % were female. Preoperatively, 67 % reported SIJ pain and mean ODI was 46.3. At 1 year, ODI improved to 30.2 (p < 0.001) and SIJ pain decreased to 8 %. Alignment correction was maintained (LL 32°→47°, SVA 83.7→45.4 mm, coronal Cobb 23.6°→11.8°). No rod or set screw failures occurred. Five patients (8 %) had distal pelvic screw lucency. Among those with CT, 87 % demonstrated definite or probable lumbosacral fusion. Conclusions: Open SIJ fusion with porous titanium implants in ASD surgery was safe, improved disability and SIJ pain, and demonstrated low distal mechanical complications at 1 year follow-up.