title: The Fate of L5-S1 With Low-Dose BMP-2 and Pelvic Fixation, With or Without Interbody Fusion, in Adult Deformity Surgery.
abstract: METHODS
  Retrospective comparative case series.
  
  
  OBJECTIVE
  Evaluate L5-S1 fusion rates when lower dose of bone morphogenic protein-2 (BMP-2) (average 3.2 mg) and pelvic fixation were used, with or without interbody fusion.
  
  
  BACKGROUND
  Pseudarthrosis at L5-S1 is one of the most common complications of long fusions to the sacrum in adult deformity surgery. Strategies for decreasing pseudarthrosis include interbody fusion, use of BMP-2 at the lumbosacral junction, and the use of sacropelvic fixation, individually or in combination. High-dose BMP-2 (20-40 mg) placed posterolaterally has shown comparable fusion rates with interbody fusion.
  
  
  METHODS
  Retrospective review of 61 consecutive patients with minimum 2-year follow-up at a single institution. All patients had an isolated posterior approach, 5 or more levels fused including L5-S1, use of pelvic fixation, and no prior L5-S1 procedures. The patients were divided in 2 groups for comparison on the basis of the use of an interbody cage/fusion at the L5-S1 level. Revision rates and implant-related complications were also reported.
  
  
  RESULTS
  The fusion rate at L5-S1 was 97% (59/61), with no difference between the interbody and no interbody fusion groups (97% vs. 96%, P = 1.0). There were no significant differences in the radiographical parameters or deformity correction between the groups. The mean amount of BMP-2 used in the interbody group was 4.1 mg (2-10), 2.5 mg (0-8) in the disc space, and 1.6 mg (0-4) in the interbody cage, whereas there was no difference in the amount of recombinant human bone morphogenic protein-2 placed posterolaterally between the 2 groups (interbody fusion = 1.6 vs. non-interbody fusion = 2.0 mg, P = 0.08) along with autograft and allograft. The overall revision rate for L5-S1 nonunion was 1.6%.
  
  
  CONCLUSIONS
  The use of low dose of BMP-2 at the L5-S1 level in combination with sacropelvic fixation achieved satisfactory fusion rates in adult deformity surgery. No additional benefit was encountered by adding an interbody cage.
  
  
  METHODS
  4.
authors.affiliation: *Department of Orthopaedics, University of Utah, Salt Lake City, UT; and †Department of Orthopaedics, University of Nevada, Las Vegas, NV.
authors.forename: Prokopis
authors.initials: P
authors.lastname: Annis
authors.forename: Darrel S
authors.initials: DS
authors.lastname: Brodke
authors.forename: William R
authors.initials: WR
authors.lastname: Spiker
authors.forename: Michael D
authors.initials: MD
authors.lastname: Daubs
authors.forename: Brandon D
authors.initials: BD
authors.lastname: Lawrence
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D055396:Bone Morphogenetic Protein 2 / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D016268:Internal Fixators; D008159:Lumbar Vertebrae; D008297:Male; D008875:Middle Aged; D011542:Pseudarthrosis / Q000000981:diagnostic imaging / Q000209:etiology*; D011859:Radiography; D012086:Reoperation; D012189:Retrospective Studies; D012447:Sacrum; D012600:Scoliosis / Q000000981:diagnostic imaging / Q000601:surgery*; D013123:Spinal Fusion / Q000009:adverse effects / Q000295:instrumentation* / Q000379:methods
chemical_list: C525718:BMP2 protein, human; D055396:Bone Morphogenetic Protein 2