title: Pedicle screw fixation for isthmic spondylolisthesis: does posterior lumbar interbody fusion improve outcome over posterolateral fusion?
abstract: OBJECTIVE
  Posterolateral fusion involving instrumentation-assisted segmental fixation represents a valid procedure in the treatment of lumbar instability. In cases of anterior column failure, such as in isthmic spondylolisthesis, supplemental posterior lumbar interbody fusion (PLIF) may improve the fusion rate and endurance of the construct. Posterior lumbar interbody fusion is, however, a more demanding procedure and increases costs and risks of the intervention. The advantages of this technique must, therefore, be weighed against those of a simple posterior lumbar fusion.
  
  
  METHODS
  Thirty-five consecutive patients underwent pedicle screw fixation for isthmic spondylolisthesis. In 18 patients posterior lumbar fusion was performed, and in 17 patients PLIF was added. Clinical, economic, functional, and radiographic data were assessed to determine differences in clinical and functional results and biomechanical properties. At 2-year follow-up examination, the correction of subluxation, disc height, and foraminal area were maintained in the group in which a PLIF procedure was performed, but not in the posterolateral fusion-only group (p < 0.05). Nevertheless, no statistical intergroup differences were demonstrated in terms of neurological improvement (p = 1), economic (p = 0.43), or functional (p = 0.95) outcome, nor in terms of fusion rate (p = 0.49).
  
  
  CONCLUSIONS
  The authors' findings support the view that an interbody fusion confers superior mechanical strength to the spinal construct; when posterolateral fusion is the sole intervention, progressive loss of the extreme correction can be expected. Such mechanical insufficiency, however, did not influence clinical outcome.
authors.affiliation: Neurosurgical Clinic, University of Messina School of Medicine, Messina, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: La Rosa
authors.forename: Alfredo
authors.initials: A
authors.lastname: Conti
authors.forename: Fabio
authors.initials: F
authors.lastname: Cacciola
authors.forename: Salvatore
authors.initials: S
authors.lastname: Cardali
authors.forename: Domenico
authors.initials: D
authors.lastname: La Torre
authors.forename: Nicola Maria
authors.initials: NM
authors.lastname: Gambadauro
authors.forename: Francesco
authors.initials: F
authors.lastname: Tomasello
mesh_terms: D000328:Adult; D000368:Aged; D001696:Biomechanical Phenomena; D001863:Bone Screws; D005260:Female; D006801:Humans; D008159:Lumbar Vertebrae; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D013123:Spinal Fusion / Q000379:methods*; D013168:Spondylolisthesis / Q000601:surgery*; D016896:Treatment Outcome