title: Reinforcement of lumbosacral instrumentation using S1-pedicle screws combined with S2-alar screws.
abstract: OBJECTIVE
  Increasing construct stability of lumbosacral instrumentations using S2-ala screws as an alternate to iliac screws.
  
  
  METHODS
  Revision surgery after failed lumbosacral fusion; long instrumentations to the sacrum; L5-S1 fusion without anterior support.
  
  
  METHODS
  Lack of sacral bone stock.
  
  
  METHODS
  Midline approach. The entry point for S2-ala screws is caudal to the posterior S1 foramen and close to the lateral sacral crest. Screw tract preparation for S2-ala screws necessitates 30-45° angulation in the axial plane. Biplanar fluoroscopy with inlet and outlet views ensure screw accuracy. With S2-ala screws, bicortical fixation is the goal.
  
  
  METHODS
  Patients are mobilized under the surveillance of physiotherapists on day 1 and released from the hospital after 10 days. Clinical and radiographic controls are performed at 6, 12 and 24 months.
  
  
  RESULTS
  Retrospective review of 80 patients undergoing S2-ala screw fixation. Main diagnosis was degenerative lumbar instability, adult scoliosis, high-grade listhesis, and nonidiopathic scoliosis. In 66% of patients, the instrumentation using S2-ala screws was part of a major lumbosacral revision surgery. Follow-up averaged 26 months. There were no deaths or major neurovascular complications. First time fusion rate at L5-S1 was greater than 90%. Eight patients (10%) experienced a complication which could be related to the S2-ala screws. Out of 160 S2-ala screws, 16 screws were judged to cause focal irritation and were removed, indicating a survival rate of 90% for the S2-ala screw.
authors.affiliation: Werner-Wicker-Clinik, German Scoliosis Center, Im Kreuzfeld 4, 34537 Bad Wildungen, Germany. Heiko.koller@t-online.de
authors.forename: H
authors.initials: H
authors.lastname: Koller
authors.forename: J
authors.initials: J
authors.lastname: Zenner
authors.forename: A
authors.initials: A
authors.lastname: Hempfing
authors.forename: L
authors.initials: L
authors.lastname: Ferraris
authors.forename: O
authors.initials: O
authors.lastname: Meier
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001863:Bone Screws; D002648:Child; D003131:Combined Modality Therapy / Q000295:instrumentation / Q000379:methods; D019544:Equipment Failure Analysis; D005260:Female; D006801:Humans; D008159:Lumbar Vertebrae / Q000601:surgery*; D008161:Lumbosacral Region / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D011474:Prosthesis Design; D011859:Radiography; D012189:Retrospective Studies; D012447:Sacrum / Q000601:surgery*; D013122:Spinal Diseases / Q000000981:diagnostic imaging* / Q000601:surgery*; D013123:Spinal Fusion / Q000295:instrumentation*; D016896:Treatment Outcome; D055815:Young Adult