title: Changes in the adjacent segment 10 years after anterior lumbar interbody fusion for low-grade isthmic spondylolisthesis.
abstract: BACKGROUND
  Adjacent segment degeneration is a long-term complication of arthrodesis. However, the incidence of adjacent segment degeneration varies widely depending on the patient's age and underlying disease and the fusion techniques and diagnostic methods used.
  
  
  OBJECTIVE
  We determined (1) the frequency of adjacent segment degeneration and increased lordosis on imaging tests, (2) the frequency and severity of clinical sequelae of these findings, including revision surgery, and (3) the sequence of degeneration and risk factors for degeneration.
  
  
  METHODS
  Seventy-three patients underwent anterior lumbar interbody fusion for low-grade isthmic spondylolisthesis at one institution between October 2000 and February 2002. Forty-nine (67%) of the original patients had complete radiographic and clinical followup for 10 years. CT and MRI were performed at 5 years and 10 years in all cases. The disc height, sagittal profiles, and facet and disc degeneration at adjacent levels were examined to identify radiographic and clinical adjacent segment degeneration. Mean followup was 134.2 months (range, 120-148 months).
  
  
  RESULTS
  Cranial segment lordosis increased (from 14.8° to 18.5°; p < 0.001), while caudal segment lordosis changed little (from 16.4° to 17.3°). Radiographic and clinical adjacent segment degeneration occurred in 19 (38.8%) and six (12.2%) patients, respectively, and two patients (4.1%) underwent revision surgery. Patients with adjacent segment degeneration had more advanced preexisting facet degeneration than patients without adjacent segment degeneration (odds ratio: 18.6; 95% CI, 1.97-175.54, p = 0.01). Acceleration of disc and facet degeneration occurred in 4.1% and 10.2%, respectively.
  
  
  CONCLUSIONS
  Adjacent segment degeneration requiring surgery is rare, although radiographic adjacent segment degeneration is common after anterior lumbar interbody fusion for isthmic spondylolisthesis. The only risk factor we found was preexisting facet degeneration of the cranial segment.
  
  
  METHODS
  Level IV, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.
authors.affiliation: Department of Neurosurgery, Wooridul Spine Hospital, Seoul, Korea.
authors.forename: Kyung-Chul
authors.initials: KC
authors.lastname: Choi
authors.forename: Jin-Sung
authors.initials: JS
authors.lastname: Kim
authors.forename: Hyeong-Ki
authors.initials: HK
authors.lastname: Shim
authors.forename: Yong
authors.initials: Y
authors.lastname: Ahn
authors.forename: Sang-Ho
authors.initials: SH
authors.lastname: Lee
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D055959:Intervertebral Disc Degeneration / Q000209:etiology / Q000601:surgery; D016015:Logistic Models; D008141:Lordosis / Q000209:etiology / Q000601:surgery; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D012086:Reoperation; D056910:Republic of Korea; D012189:Retrospective Studies; D012307:Risk Factors; D012720:Severity of Illness Index; D013123:Spinal Fusion / Q000009:adverse effects / Q000379:methods*; D013168:Spondylolisthesis / Q000175:diagnosis / Q000503:physiopathology / Q000601:surgery*; D013997:Time Factors; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome