title: Surgical treatment of adjacent instability after lumbar spine fusion.
abstract: METHODS
  This study is a retrospective review of 39 patients with previous instrumented lumbar fusion who underwent secondary spine surgery for lumbar adjacent instability. To the authors' knowledge, this is the largest study of surgical treatment of lumbar adjacent instability in the literature to date.
  
  
  OBJECTIVE
  This study evaluated the feasibility of adjacent instability treated with medial facetectomy, fusion with autologous bone grafting, and pedicle screw instrumentation.
  
  
  BACKGROUND
  The surgical treatment of adjacent instability has seldom been discussed. Revision spine fusions are challenged by high pseudarthrosis rates.
  
  
  METHODS
  Thirty-nine patients with previous lumbar fusion underwent second lumbar spine surgery for adjacent instability. All were treated with autogenous posterolateral arthrodesis and transpedicle screw fixation in addition to decompressive laminectomy. Medical records, radiographs, and pain scores were obtained.
  
  
  RESULTS
  The clinical results were excellent or good in 76.9% of patients, and the radiographic fusion was successful in 37 (94.9%) of patients. Flat back was noted in 8 (20.5%) of patients. In 5 patients (12.8%), neighboring segment breakdown again developed, and 2 of those patients underwent a third lumbar fusion. Dural tear during operation occurred in 2 patients. One patient experienced cauda equina syndrome but recovered bladder function 1 month later.
  
  
  CONCLUSIONS
  Autogenous posterolateral arthrodesis combined with pedicle screw fixation led to successful radiologic and clinical outcome in patients with lumbar adjacent instability. Adequate decompression of the adjacent stenosis requires medial facetectomy, thus preventing aggressive nerve root manipulation and reducing the incidence of dural tear.
authors.affiliation: Department of Orthopaedic Surgery, Chang Gung Memorial Hospital, Taoyuan, Taiwan. chenwenj@adm.cgmh.org.tw
authors.forename: W J
authors.initials: WJ
authors.lastname: Chen
authors.forename: P L
authors.initials: PL
authors.lastname: Lai
authors.forename: C C
authors.initials: CC
authors.lastname: Niu
authors.forename: L H
authors.initials: LH
authors.lastname: Chen
authors.forename: T S
authors.initials: TS
authors.lastname: Fu
authors.forename: C B
authors.initials: CB
authors.lastname: Wong
mesh_terms: D000368:Aged; D001863:Bone Screws; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000000981:diagnostic imaging / Q000209:etiology* / Q000601:surgery*; D008159:Lumbar Vertebrae / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D011859:Radiography; D012086:Reoperation; D012189:Retrospective Studies; D013122:Spinal Diseases / Q000000981:diagnostic imaging / Q000209:etiology* / Q000601:surgery*; D013123:Spinal Fusion / Q000009:adverse effects*; D016896:Treatment Outcome