Introduction: Adult deformity patients undergoing long fusion to the sacrum often require fixation into the ilium. There are many techniques currently available, some are technically difficult & require complex connectors that may affect the construct stability
Methods: We prospectively reviewed 52 consecutive adults undergoing long fusion to the Sacrum using (S2AI) Screws. The technique uses a starting point in the S2 Ala, directed toward the anterior inferior iliac spine, allowing an in‐line anchor without additional dissection. Functional outcome, radiographic data and complications were collected. 46 patients completed 2 yrs follow‐up, mean 2.5 yrs.
Results: The mean age was 59.8 yrs (±13.0, 23.8–80.8). 76.9 % female, 45 patients had multiple comorbidities. Mean radiographic changes were (pre‐/post): thoracic kyphosis 7.4° (34.2/41.3), lumbar lordosis 13.0°(34.3/47.3), thoracic curve 10.9°(22.3/15.1), lumbar curve 15.1°(30.4/15.3), pelvic obliquity 1.6 (±5.1, ‐5.5–19.1). At 2 yrs, 92% of the patients showed radiographic fusion at L4‐S1. 2 patients had 3 (S2I) screws fracture, neither required revision. Re‐operation was performed on 5 patients: improper screw placement (1), pseudoarthrosis proximal to L4 (2), junctional stenosis (1), residual deformity (1). Overall complication rate was 40.4% (7.7% minor, 34.6 % major). Complications specific to S2‐iliac fixation: screw breakage 2, screw misplacement 1. There was stastically significant improvement in all SRS 22 domains; (pre‐/post): pain 1.1 (2.17/3.22), self image 1.1 (2.12/3.19), activity 0.8 (2.39/3.16), mental 1.2 (1.89–3.07), and satisfaction 0.9 (1.91/2.84). The ODI showed a mean decrease 13.4 (40.16/26.79), the SF‐12 improvement (physical 12.3, mental 2.2). The VAS showed 5 patients with right SI‐joint area pain (mean 4.8), 4 patients had left side pain (mean 5.5). There was one superficial and one deep wound infections.
Conclusion: S2 Alar Iliac (S2AI) fixation is an easy, safe & effective method to achieve sacropelvic fixation. Complications related to the technique are rare and the revision rate is low
Significance: We are introducing a new technique for sacro‐pelvic fixation that has the potential to simplify fusion to the sacrum, lower complications & improve outcome in spinal deformity surgery