Iliac screw versus S2 alar-iliac screw fixation in adults: a meta-analysis

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In a meta-analysis, the authors sought to compare outcomes after iliac screw (IS) versus S2 alar-iliac (S2AI) screw fixation in adult patients.


A PubMed/MEDLINE database search was performed for studies comparing IS and S2AI screw fixation techniques in adults. Levels of evidence were assigned based on the North American Spine Society guidelines. Three outcomes were examined: 1) revision surgery rate secondary to mechanical failure or wound complications, 2) surgical site infection rate, and 3) screw prominence/pain. Data were pooled and outcomes compared between techniques. Absolute risk reductions (ARRs) were also calculated for outcome measures.


Five retrospective cohort studies (all level III evidence) were included in our analysis. A total of 323 adult patients were included—147 in the IS group (45.5%) and 176 in the S2AI group (54.5%). Overall, revision surgery due to mechanical failure or wound complications was needed in 66 of 323 patients (revision surgery rate 20.4%)—27.9% in the IS group and 14.2% in the S2AI group (13.7% ARR; p < 0.001). Four studies reported wound infections among 278 total patients, with an infection rate of 12.6% (35/278)—25.4% in the IS group and 2.6% in the S2AI group (22.8% ARR; p < 0.001). Three studies examined development of screw prominence/pain; combined, these studies reported screw prominence/pain in 21 of 215 cases (9.8%)—18.1% in the IS group and 1.8% in the S2AI group (16.3% ARR; p < 0.001).


S2AI screw fixation in adults has a significantly lower mechanical failure and complication rate than IS fixation based on the current best available evidence.

ABBREVIATIONS ARR = absolute risk reduction; IS = iliac screw; NASS = North American Spine Society; S2AI = S2 alar-iliac.

Article Information

Correspondence Reza Yassari: Montefiore Medical Center/Albert Einstein College of Medicine, Bronx, NY.

INCLUDE WHEN CITING Published online November 9, 2018; DOI: 10.3171/2018.7.SPINE18710.

Disclosures Daniel M. Sciubba has consulting agreements with DePuy Synthes, Medtronic, Stryker, NuVasive, K2M, and Baxter. Reza Yassari has a consulting agreement with Stryker.

© AANS, except where prohibited by US copyright law.



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    Flowchart of literature search and study selection. Figure is available in color online only.

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    Risk of bias in individual studies. Figure is available in color online only.

  • View in gallery

    Forest plot showing rates of revision surgery across studies. The meta-analysis revealed a significantly lower risk of reoperation in patients receiving S2AI screws (p < 0.001). Figure is available in color online only.

  • View in gallery

    Forest plot showing rates of wound infection across studies. The meta-analysis revealed a significantly lower risk of infection in patients receiving S2AI screws (p < 0.0001). Figure is available in color online only.

  • View in gallery

    Forest plot showing rates of screw prominence/pain across studies. The meta-analysis revealed a significantly lower risk of screw prominence/pain in patients receiving S2AI screws (p = 0.006). Figure is available in color online only.



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