Comparison Between S2-Alar-Iliac Screw Fixation and Iliac Screw Fixation in Adult Deformity Surgery: Reoperation Rates and Spinopelvic Parameters

Abstract

Study Design:Retrospective cohort study.Objective:The S2-alar-iliac (S2AI) technique has been described as an alternative method for pelvic fixation in place of iliac screws (ISs) in spinal deformity surgery. The objective of this study was to analyze the impact of S2AI screws on radiographical outcomes, including spinopelvic parameters.Methods:A retrospective review of 17 patients receiving ISs and 46 patients receiving S2AI screws for correction of adult spinal deformity between 2010 and 2015 with minimum 1-year follow-up was conducted. Patient data on postoperative complications, including reoperation rates and proximal junctional kyphosis (PJK), and radiographical parameters was collected and statistically analyzed.Results:With mean follow-up of 21.1 months, the overall reoperation rate was significantly lower in the S2AI group than in the IS group (21.7% vs 58.8%, P = .01), but the incidence of PJK was similar (32.6% vs 35.3%, P > .99). Moreover, the time to reoperation in the IS group was significantly shorter than in the S2AI group (P = .001), and the S2AI group trended toward a longer time to reoperation due to PJK (P = .08). There was a significantly higher change in pelvic incidence (PI) in the S2AI group (−6.0°) compared with the IS group (P = .001).Conclusions:Compared with the IS technique, the S2AI technique demonstrated a lower rate of overall reoperation, a similar rate of PJK, longer time to reoperation, and possible reduction in PI. Future studies may be warranted to clarify the mechanism of these results and how they can be translated into improved patient care.

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

“…The 5 selected studies were all retrospective cohort studies comparing outcomes of IS fixation and S2AI screw fixation techniques in adults. 5,[7][8][9]13 Based on the NASS guidelines, all studies were graded as level III evidence (retrospective comparative studies). After risk-of-bias analysis, it was found that all studies had a high risk of selection and performance bias given their nonrandomized and nonblinded nature (Fig.…”

“…2). Detection, attrition, and reporting bias were lower compared to selection and performance biases, but they were also present given that the studies did not blind outcomes (except for the study by Ishida et al 9 ) and tended to inconsistently report outcomes.…”

“…As summarized in Table 1, all 5 studies were published between 2015 and 2017. 5,[7][8][9]13 Cumulatively, a total of 323 adult patients were included in the analysis-147 in the IS group (45.5%) and 176 in the S2AI group (54.5%). The average age of patients was between 59 and 64 years and 21%-44% were male.…”

“…The most common indication for spinopelvic fixation was spinal deformity in 91.3% of all patients. Use of anterior column support at the L5-S1 level also varied from 0% of cases in the series by Guler et al to 100% of cases in the series by Ishida et al 7,9 Average follow-up time ranged from 17.6 to 29.6 months.…”

“…18 Nonetheless, concerns include the need for more extensive soft-tissue dissection, need for complex connector systems, instrumentation pain/prominence, and others. 10 On the other hand, S2AI screws were first described for use in pediatric patients with scoliosis 19 but have gained popularity in adult patients given recently reported favorable outcomes, 5,9 including lower complication rates and no need for connectors (given that they are placed in line with lumbar and S1 pedicle screws), among others. 10 The purpose of the present study was to conduct a me-ta-analysis comparing IS fixation and S2AI screw fixation techniques in adults, with an emphasis on rates of revision surgery and wound complications.…”