title: Outcomes of L1-L2 posterior lumbar interbody fusion with the Lumbar I/F cage and the variable screw placement system: reporting unexpected poor fusion results at L1-L2.
abstract: BACKGROUND
  Posterior lumbar interbody fusion (PLIF) was introduced 50 years ago. The Lumbar I/F cage (DePuy Spine, Raynham, MA) was designed to enhance PLIF results. PLIF with the Lumbar I/F cage and posterior Variable Screw Placement System (VSP) has increased the success of fusion to nearly 100% at the four lowest lumbar levels, L2-L3 through L5-S1. Less commonly, PLIF is indicated for the L1-L2 level. Clinical-results of Lumbar I/F cage fusion and VSP at L1-L2 have-not been reported.
  
  
  OBJECTIVE
  The purpose of this study is to report the functional outcomes, fusion rate, and complications related to PLIF with Lumbar I/F cage and VSP of L1-L2
  
  
  METHODS
  The setting is a retrospective, single-arm cohort study of consecutive PLIF surgical patients at a single center.
  
  
  METHODS
  A review of 373 of 425 patients who underwent PLIF with Lumbar I/F cage and VSP from 1999 to 2002 identified 12 patients who had PLIF with Lumbar I/F cage and VSP at L1-L2. Mean follow-up was 31 months (range 12-65 months).
  
  
  METHODS
  Clinical success was determined with a modified Prolo score evaluating pain, function, medication usage and economic status. Fusion success, determined by evaluation of plain radiographs, was defined by continuous bone bridging the fusion area with no lucencies.
  
  
  METHODS
  The 12 patients were evaluated for clinical success and/fusion success at last follow-up. These results were compared with the results of the 373 patients reviewed, and historical groups of the original Investigational Device Exemption study and the 10-year follow-up study.
  
  
  RESULTS
  Previous surgery was reported by 10 of 12 patients, with an average symptom-free period of 3 years after previous fusion and before presentation with severe symptomatology necessitating further surgery at L1-L2. Seven patients had clinical success (59%), and five patients were clinically unsuccessful (41%). This included zero excellent, 2 of 12 (15%) good, 5 of 12 (42%) fair, and 5 of 12 (42%) poor results. Fusion was successful in seven (58%) and failed in five patients (42%). Three failed fusions were associated with L1-L2 subsidence. Two patients required further revision for non-union.
  
  
  CONCLUSIONS
  In 12 patients with L1-L2 fusion, we report an unexpected high rate of failed fusion and poor clinical outcome.
authors.affiliation: South Texas Orthopaedic and Spinal Surgery Associates, 9150 Huebner Road, San Antonio, 78240, USA. gfogel@spinetex.com
authors.forename: Guy R
authors.initials: GR
authors.lastname: Fogel
authors.forename: John S
authors.initials: JS
authors.lastname: Toohey
authors.forename: Arvo
authors.initials: A
authors.lastname: Neidre
authors.forename: John W
authors.initials: JW
authors.lastname: Brantigan
mesh_terms: D001860:Bone Plates; D001863:Bone Screws; D004867:Equipment Design; D006801:Humans; D016268:Internal Fixators; D008159:Lumbar Vertebrae / Q000601:surgery*; D012086:Reoperation; D012189:Retrospective Studies; D013123:Spinal Fusion / Q000009:adverse effects / Q000379:methods*; D013524:Surgical Flaps; D017211:Treatment Failure