title: Fate of S2-Alar-Iliac Screws After 12-Month Minimum Radiographic Follow-up: Preliminary Results.
abstract: S2-alar-iliac (S2AI) screws are 1 technique for lumbopelvic fixation to improve fusion rates across the lumbosacral junction that has gained wider acceptance. The S2AI screw crosses the cortical surfaces of the sacroiliac joint (SIJ), which may improve the biomechanical strength of the instrumentation.
  
  
  
  To report preliminary radiographic outcomes of patients who underwent lumbopelvic fixation with S2AI screws with a minimum 12-month follow-up.
  
  
  
  We retrospectively reviewed adult patients who underwent lumbopelvic fixation with S2AI screws. Patients with computed tomography (CT) scans obtained preoperatively and ≥12 months postoperatively were reviewed to determine whether there was S2AI screw backout or breakage, periscrew lucency, or SIJ degeneration, and to assess L5-S1 fusion status.
  
  
  
  Twenty-six S2AI screws in 13 patients were evaluated (mean follow-up 24.8 months [14-52 months]). Nine patients had L5-S1 interbody grafts. Partial periscrew lucency was identified in 7 S2AI screws (27%) in 5 patients (38%), and L5-S1 fusion occurred in 92% of patients. L5-S1 nonunion was seen in 1 patient (8%), who had evidence of bilateral screw loosening in the sacral portion. Four patients with screw loosening had an osseous L5-S1 fusion. No patients had radiographic evidence of progression of SIJ degeneration, experienced screw backout or breakage, required reoperation for L5-S1 nonunion, or had S2AI screw-related complication.
  
  
  
  S2AI screws maintained their integrity without causing SIJ degeneration or major screw-related complications in this small retrospective series with short follow-up. Long-term results are needed to evaluate the durability of S2AI screws over time.
authors.affiliation: Department of Neurosurgery, Clinical Neurosciences Center, University of Utah, Salt Lake City, Utah.
authors.forename: Marcus D
authors.initials: MD
authors.lastname: Mazur
authors.affiliation: Department of Neurosurgery, Clinical Neurosciences Center, University of Utah, Salt Lake City, Utah.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Mahan
authors.affiliation: Department of Radiology, Clinical Neurosciences Center, University of Utah, Salt Lake City, Utah.
authors.forename: Lubdha M
authors.initials: LM
authors.lastname: Shah
authors.affiliation: Department of Neurosurgery, Clinical Neurosciences Center, University of Utah, Salt Lake City, Utah.
authors.forename: Andrew T
authors.initials: AT
authors.lastname: Dailey
mesh_terms: D000328:Adult; D000368:Aged; D001863:Bone Screws; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007085:Ilium / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D012086:Reoperation; D012189:Retrospective Studies; D012446:Sacroiliac Joint; D012447:Sacrum / Q000601:surgery; D013122:Spinal Diseases / Q000000981:diagnostic imaging / Q000209:etiology / Q000601:surgery*; D013123:Spinal Fusion / Q000295:instrumentation* / Q000379:methods; D014057:Tomography, X-Ray Computed
keywords: Fusion; Lumbopelvic fixation; Outcomes; S2-alar-iliac screws