title: Robotic Guidance for S2-Alar-Iliac Screws in Spinal Deformity Correction.
abstract: A retrospective cohort study of patients who underwent S2-alar-iliac (S2AI) screw insertion using robotic guidance in long constructs for spinal deformity correction extending to the sacrum performed at a single institution.
  
  
  
  To assess and evaluate the feasibility and accuracy of robotic guidance for S2AI screw insertion.
  
  
  
  Pelvic fixation has become a common adjunct to long fusions extending to the sacrum. The S2AI method possesses advantages over the traditional Galveston technique. S2AI involves finding a pathway from S2 across the sacral ala and the sacroiliac joint into the ilium. Robotic guidance is a new modality for implant insertion that has shown high accuracy.
  
  
  
  We identified all patients who underwent robotic-guided S2AI screw insertion in long constructs extending to the sacrum. Cortical breaches and protrusions, assessed on postoperative imaging, and complications were recorded.
  
  
  
  Fourteen patients (31 screws) underwent S2AI screw insertion using robotic guidance and free-hand probing. Average screw length was 80 mm (range, 65-90 mm). All trajectories were confirmed as accurate (no proximal breaches). Screw insertion, performed manually, resulted in 10 protrusions <2 mm, 1 by 2-4 mm, and 6 by ≥4 mm. No screw was intrapelvic or risked any visceral or neurovascular structures and none required removal or revision. Longer screws (>80 mm) were associated with distal protrusion.
  
  
  
  Robotic-guided S2AI screws are accurate and a feasible option. Although no complications from protrusion were identified, larger studies and instrumentation modifications are required to assess the clinical acceptance of robotic guidance in sacropelvic fixation.
authors.affiliation: Department of Orthopaedic Surgery, University of California-Irvine, Irvine, CA.
authors.forename: S Samuel
authors.initials: SS
authors.lastname: Bederman
authors.forename: Peter
authors.initials: P
authors.lastname: Hahn
authors.forename: Vincent
authors.initials: V
authors.lastname: Colin
authors.forename: P Douglas
authors.initials: PD
authors.lastname: Kiester
authors.forename: Nitin N
authors.initials: NN
authors.lastname: Bhatia
mesh_terms: D000328:Adult; D000368:Aged; D001863:Bone Screws; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007085:Ilium / Q000000981:diagnostic imaging / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D065287:Robotic Surgical Procedures / Q000295:instrumentation / Q000379:methods / Q000592:standards; D012447:Sacrum / Q000000981:diagnostic imaging / Q000601:surgery*; D013121:Spinal Curvatures / Q000000981:diagnostic imaging / Q000601:surgery*; D013123:Spinal Fusion / Q000379:methods*; D015898:Tomography Scanners, X-Ray Computed