title: Reamed transacral interbody fusion for L5-s1 pseudoarthrosis: a novel salvage technique in 10 patients.
abstract: METHODS
  A retrospective cohort study.
  
  
  OBJECTIVE
  To present the technique, radiographic, and clinical outcomes of a series of patients who underwent a novel method for revision L5-S1 interbody fusion.
  
  
  BACKGROUND
  Pseudoarthrosis at L5-S1 is a relatively common problem after long fusion to the sacrum. Revision approach to L5-S1 for cage or graft removal by anterior lumbar interbody fusion, posterior lumbar interbody fusion, or transforaminal interbody fusion is challenging and potentially dangerous which makes salvage by a posterior reamed transacral technique appealing.
  
  
  METHODS
  Consecutive patients with symptomatic pseudoarthrosis at L5-S1, who underwent posterior reamed fluoroscopically guided fusion were identified over a 3-year period. Operative notes, medical records, preoperative and postoperative plain radiographs, computed tomography scans, Visual Analog Scores (VAS) (lower extremity and low back) preoperatively, and at most recent follow-up were studied.
  
  
  RESULTS
  Ten patients (age, 53±2.8 y) with prior lumbar spinal operations (mean, 3.5±0.6) met the inclusion criteria. Prior procedures at L5-S1 were anterior lumbar interbody fusion (n=4), posterior lumbar interbody fusion (n=3), and posterolateral fusion (n=3). Mean Meyerding grade was 1.41 (range, 0-4). Reaming was performed between the S1 and S2 (n=9) or S2 and S3 (n=1) nerve roots and allowed fragmentation/removal of polyetheretherketone interbody grafts (n=3) or femoral ring allografts (n=3). Transacral Harms cage (n=8) or autograft (n=1) was passed through the reamed channel or a carbon fiber-reinforced polyetheretherketone directly into the interspace (n=1). VAS scores lower extremity (P=0.003) and low back (P=0.001) were improved at a mean follow-up of 13.5±3.6 months. No neurologic sequelae occurred and solid fusion was achieved in 9/10 (90%).
  
  
  CONCLUSIONS
  We report a series of patients who underwent a novel revision technique for symptomatic lumbosacral pseudoarthrosis. Despite the small numbers in this cohort, a salvage technique is presented that permitted fusion as confirmed by computed tomography scan and improved VAS scores in the majority of patients. The data suggest that this technique should be considered as an alternative to the revision anterior or posterior approaches to L5-S1 and merits further investigation.
authors.affiliation: Hospital for Special Surgery, The Spine Care Institute, New York, NY 10021, USA. drlebl@stanfordalumni.org
authors.forename: Darren R
authors.initials: DR
authors.lastname: Lebl
authors.forename: Andrew A
authors.initials: AA
authors.lastname: Sama
authors.forename: Matthias
authors.initials: M
authors.lastname: Pumberger
authors.forename: Suhel
authors.initials: S
authors.lastname: Kotwal
authors.forename: Frank P
authors.initials: FP
authors.lastname: Cammisa
authors.forename: Federico P
authors.initials: FP
authors.lastname: Girardi
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000293:injuries / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D011542:Pseudarthrosis / Q000000981:diagnostic imaging / Q000601:surgery*; D011859:Radiography; D012189:Retrospective Studies; D012447:Sacrum / Q000000981:diagnostic imaging / Q000293:injuries / Q000601:surgery*; D013123:Spinal Fusion / Q000295:instrumentation / Q000379:methods*; D016896:Treatment Outcome