Medical Student USF Morsani College of Medicine Tampa, FL, US
Introduction: Pelvic screw fixation is essential in adult spinal deformity (ASD) surgeries to provide stability, particularly in cases requiring robust constructs. Despite its benefits, pelvic screws near the sacroiliac joint (SIJ) are often associated with concerns about postoperative SIJ pain. This study investigates whether screw placement adjacent to the SIJ, including the modified iliac bolt and the S2 alar-iliac (S2AI) screw, increases postoperative buttock or sitting pain.
Methods: We retrospectively reviewed 123 ASD patients (246 pelvic sides) who underwent bilateral pelvic screw fixation. Postoperative images were used to categorize screws as classic iliac bolts, modified iliac bolts, or S2AI screws. Patients reported postoperative pain, specifically residual buttock pain or pain when standing or sitting. Screw combinations were analyzed using SPSS with chi-square tests to determine associations with pain.
Results: Six screw combinations were identified: classic (46), modified (64), S2AI (69), classic+modified (22), classic+S2AI (15), and modified+S2AI (30). None of the combinations significantly increased postoperative pain (p=0.234; p=0.674). Screws traversing or adjacent to the SIJ did not increase buttock or sitting pain compared to classic screws (p=0.407; p=0.770). Modified screws showed a 2.25x reduction in buttock pain and a 1.92x reduction in sitting pain (p=0.019; p=0.04) compared to other techniques. When excluding mixed screw combinations, no significant differences were observed (p=0.198; p=0.506). The number of screws per pelvic side also showed no correlation with increased pain (p=0.161; p=0.681).
Conclusion : Contrary to common assumptions, neither S2AI nor modified iliac screws increase postoperative buttock or sitting pain. In fact, the modified technique may reduce the incidence of pain by stabilizing the joint. These findings suggest that pelvic screw fixation, including adjacent SIJ techniques, is safe and effective in minimizing SIJ-related pain.