title: Surgical outcomes of degenerative lumbar spondylolisthesis with anterior vacuum disc: can the intervertebral cage overcome intradiscal vacuum phenomenon and enhance posterolateral fusion?
abstract: BACKGROUND
  The vacuum phenomenon within an intervertebral disc is not an uncommon radiographic finding in the elderly. However, no reports in the English literature have focused on the effect of an anterior vacuum disc in relation to surgical outcome of same-segment spondylolisthesis. We hypothesized that instrumented posterolateral fusion is not adequate in this situation and that additional interbody fusion with cages would provide better radiographic and clinical outcomes.
  
  
  METHODS
  The medical records of 72 patients who underwent instrumented fusion for one-segment degenerative lumbar spondylolisthesis with a vacuum disc were reviewed. Thirty-three patients were placed in the noncage group and 39 in the cage group based on whether or not augmentation with an intervertebral cage was carried out. Radiographic parameters (disc height, translation, intradiscal angle, segmental angle, and fusion) on preoperative, postoperative, and final radiographs were compared between groups. The Oswestry Disability Index (ODI) and Brosky criteria were used to evaluate clinical outcomes.
  
  
  RESULTS
  Blood loss and operation time were greater in the cage group but without a significant difference (p = 0.271, p = 0.108, respectively). Preoperative radiographic data were similar between groups, but the cage group had more intradiscal lordosis, less translation, a higher disc height after surgery, and maintained these advantages at the final follow-up. In addition, the posterolateral fusion rate was significantly higher in the cage group (92.3% vs. 56.1%, p < 0.001), and they obtained more ODI improvement (30.62 vs. 26.39, p = 0.369) and a higher final satisfaction rate (79.5% vs. 57.6%, p = 0.044). There was no decrease in the incidence of developed adjacent segmental disease in the noncage group.
  
  
  CONCLUSIONS
  The vacuum sign at the spondylolisthesis segment should be regarded as another sign of instability. We suggest that instrumented posterolateral fusion simultaneous with intervertebral fusion with a cage can overcome this situation.
authors.affiliation: Department of Orthopedic Surgery, Chang Gung Memorial Hospital, Chang Gung University, No. 5, Fu-Shin Street, Kweishian, Taoyuan, 333, Taiwan, jcl1265@adm.cgmh.org.tw.
authors.forename: Jen-Chung
authors.initials: JC
authors.lastname: Liao
authors.forename: Meng-Ling
authors.initials: ML
authors.lastname: Lu
authors.forename: Chi-Chien
authors.initials: CC
authors.lastname: Niu
authors.forename: Wen-Jer
authors.initials: WJ
authors.lastname: Chen
authors.forename: Lih-Hui
authors.initials: LH
authors.lastname: Chen
mesh_terms: D000368:Aged; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D055959:Intervertebral Disc Degeneration / Q000000981:diagnostic imaging / Q000601:surgery*; D008159:Lumbar Vertebrae; D008297:Male; D008875:Middle Aged; D011859:Radiography; D012189:Retrospective Studies; D013123:Spinal Fusion / Q000379:methods*; D013168:Spondylolisthesis / Q000000981:diagnostic imaging / Q000601:surgery*; D013997:Time Factors; D016896:Treatment Outcome; D014618:Vacuum