title: Utilization of iliac screws and structural interbody grafting for revision spondylolisthesis surgery.
abstract: METHODS
  Retrospective case analysis and presentation.
  
  
  OBJECTIVE
  The purpose of this article is to discuss the spectrum of failed spondylolisthesis cases for which either anterior column support or iliac screw fixation or both are useful in salvaging failed spondylolisthesis surgeries.
  
  
  BACKGROUND
  Past studies and experience have suggested that there is a relatively high rate of sacral screw failure both in long constructs to the sacrum in the adult population and also with treatment of both high-grade and adult spondylolisthesis at L5-S1. It has been noted that anterior column support at L5-S1 and additional fixation points in the sacropelvic unit provide some protection to the sacral screws.
  
  
  METHODS
  This article details the author's personal and institutional experience with sacropelvic fixation and anterior column support at L5-S1 to salvage failed spondylolisthesis cases.
  
  
  RESULTS
  To some extent, each case needs to be individualized. It is not always necessary to provide both anterior column support at L5-S1 and protection of the sacral screws with iliac screws. However, in the most complex problems using both seems to provide the greatest chance for an acceptable radiographic and clinical outcome. Most biomechanical studies have supported the use of anterior column support and iliac fixation to protect sacral screws, suggesting, of the two, that the iliac screws are more valuable.
  
  
  CONCLUSIONS
  For many of these cases of both high-grade dysplastic spondylolisthesis and low-grade adult isthmic spondylolisthesis, a reasonable combination of anterior column support and/or iliac screw fixation may be logical to reduce the incidence of failure and need for revision. The biggest concern with using iliac screw fixation is that these screws are prominent in a percentage of patients and the ultimate impact on the sacroiliac joint is not fully investigated. However, at our institution with 5- to 10-year follow-up, the impact on the sacroiliac joint has been minimal.
authors.affiliation: Washington University School of Medicine, Department of Orthopaedic Surgery, One Barnes-Jewish Hospital Plaza, Suite 11300 WP, Campus Box 8233, St. Louis, MO 63110, USA. bridwellk@wustl.edu
authors.forename: Keith H
authors.initials: KH
authors.lastname: Bridwell
mesh_terms: D000328:Adult; D001863:Bone Screws / Q000009:adverse effects; D016025:Bone Transplantation; D019299:Decompression, Surgical; D018450:Disease Progression; D004868:Equipment Failure; D005260:Female; D015775:Fractures, Stress / Q000209:etiology; D006801:Humans; D007085:Ilium / Q000000981:diagnostic imaging / Q000601:surgery*; D008159:Lumbar Vertebrae / Q000601:surgery; D008297:Male; D009984:Orthopedic Fixation Devices / Q000009:adverse effects; D019637:Orthopedic Procedures / Q000009:adverse effects; D011859:Radiography; D012086:Reoperation; D012189:Retrospective Studies; D012447:Sacrum / Q000601:surgery; D016103:Spinal Fractures / Q000209:etiology; D013123:Spinal Fusion / Q000009:adverse effects / Q000379:methods; D013168:Spondylolisthesis / Q000000981:diagnostic imaging / Q000601:surgery*; D017211:Treatment Failure