Low rates of complications after spinopelvic fixation with iliac screws in 260 adult patients with a minimum 2-year follow-up

Abstract

OBJECTIVE Recent literature describing complications associated with spinopelvic fixation with iliac screws in adult patients has been limited but has suggested high complication rates. The authors’ objective was to report their experience with iliac screw fixation in a large series of patients with a 2-year minimum follow-up. METHODS Of 327 adult patients undergoing spinopelvic fixation with iliac screws at the authors’ institution between 2010 and 2015, 260 met the study inclusion criteria (age ≥ 18 years, first-time iliac screw placement, and 2-year minimum follow-up). Patients with active spinal infection were excluded. All iliac screws were placed via a posterior midline approach using fluoroscopic guidance. Iliac screw heads were deeply recessed into the posterior superior iliac spine. Clinical and radiographic data were obtained and analyzed. RESULTS Twenty patients (7.7%) had iliac screw–related complication, which included fracture (12, 4.6%) and/or screw loosening (9, 3.5%). No patients had iliac screw head prominence that required revision surgery or resulted in pain, wound dehiscence, or poor cosmesis. Eleven patients (4.2%) had rod or connector fracture below S1. Overall, 23 patients (8.8%) had L5–S1 pseudarthrosis. Four patients (1.5%) had fracture of the S1 screw. Seven patients (2.7%) had wound dehiscence (unrelated to the iliac screw head) or infection. The rate of reoperation (excluding proximal junctional kyphosis) was 17.7%. On univariate analysis, an iliac screw–related complication rate was significantly associated with revision fusion (70.0% vs 41.2%, p = 0.013), a greater number of instrumented vertebrae (mean 12.6 vs 10.3, p = 0.014), and greater postoperative pelvic tilt (mean 27.7° vs 23.2°, p = 0.04). Lumbosacral junction–related complications were associated with a greater mean number of instrumented vertebrae (12.6 vs 10.3, p = 0.014). Reoperation was associated with a younger mean age at surgery (61.8 vs 65.8 years, p = 0.014), a greater mean number of instrumented vertebrae (12.2 vs 10.2, p = 0.001), and longer clinical and radiological mean follow-up duration (55.8 vs 44.5 months, p < 0.001; 55.8 vs 44.6 months, p < 0.001, respectively). On multivariate analysis, reoperation was associated with longer clinical follow-up (p < 0.001). CONCLUSIONS Previous studies on iliac screw fixation have reported very high rates of complications and reoperation (as high as 53.6%). In this large, single-center series of adult patients, iliac screws were an effective method of spinopelvic fixation that had high rates of lumbosacral fusion and far lower complication rates than previously reported. Collectively, these findings argue that iliac screw fixation should remain a favored technique for spinopelvic fixation.