title: ISSLS Prize winner: Long-term follow-up suggests spinal fusion is associated with increased adjacent segment disc degeneration but without influence on clinical outcome: results of a combined follow-up from 4 randomized controlled trials.
abstract: METHODS
  Cross-sectional analysis of long-term follow-up (LTFU) data from 4 randomized controlled trials of operative versus nonoperative treatment for chronic low back pain.
  
  
  OBJECTIVE
  To examine the influence of spinal fusion on adjacent segment disc space height as an indicator of disc degeneration at LTFU.
  
  
  BACKGROUND
  There is ongoing debate as to whether adjacent segment disc degeneration results from the increased mechanical stress of fusion.
  
  
  METHODS
  Plain standing lateral radiographs were obtained at LTFU (mean, 13 ± 4 yr postrandomization) in 229 of 464 (49%) patients randomized to surgery and 140 of 303 (46%), to nonoperative care. Disc space height and posteroanterior displacement were measured for each lumbar segment using a validated computer-assisted distortion compensated roentgen analysis technique. Values were reported in units of standard deviations above or below age and sex-adjusted normal values. Patient-rated outcomes included the Oswestry Disability Index and pain scales.
  
  
  RESULTS
  Radiographs were usable in 355 of 369 (96%) patients (259 fusion and 96 nonoperative treatment). Both treatment groups showed significantly lower values for disc space height of the adjacent segment than norm values. There was a significant difference between treatment groups for the disc space height of the cranial adjacent segment (in both as-treated and intention-to-treat analyses). The mean treatment effect of fusion on adjacent segment disc space height was -0.44 SDs (95% CI, -0.77 to -0.11; P = 0.01; as-treated analysis); there was no group difference for posteroanterior displacement (0.18 SDs, 95% confidence interval, -0.28 to 0.64, P = 0.45). Adjacent level disc space height and posteroanterior displacement were not correlated with Oswestry Disability Index or pain scores at LTFU (r = 0.010-0.05; P > 0.33).
  
  
  CONCLUSIONS
  Fusion was associated with lower disc space height at the adjacent segment after an average of 13 years of FU. The reduced disc space height had no influence on patient self-rated outcomes (pain or disability).
  
  
  METHODS
  2.
authors.affiliation: *Spine Center, Schulthess Klinik, Zurich, Switzerland †Department of Clinical Medicine, Neuromuscular Diseases Research Group, University of Tromso, Norway ‡Departments of Physical Medicine and Rehabilitation and Orthopedics, Oslo University Hospital and Oslo University, Norway §Neuroortopediskt Centrum, Länssjukhuset Ryhov, Jönköping, Sweden ¶Spine Center Göteborg, Gruvgatan, Vä Frölunda, Sweden; and ‖Nuffield Orthopaedic Centre, Oxford University Hospitals, Oxford, United Kingdom.
authors.forename: Anne F
authors.initials: AF
authors.lastname: Mannion
authors.forename: Gunnar
authors.initials: G
authors.lastname: Leivseth
authors.forename: Jens-Ivar
authors.initials: JI
authors.lastname: Brox
authors.forename: Peter
authors.initials: P
authors.lastname: Fritzell
authors.forename: Olle
authors.initials: O
authors.lastname: Hägg
authors.forename: Jeremy C T
authors.initials: JC
authors.lastname: Fairbank
mesh_terms: D000328:Adult; D000368:Aged; D003430:Cross-Sectional Studies / Q000379:methods; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007403:Intervertebral Disc / Q000473:pathology*; D055959:Intervertebral Disc Degeneration / Q000175:diagnosis / Q000473:pathology*; D007405:Intervertebral Disc Displacement / Q000473:pathology*; D017116:Low Back Pain / Q000473:pathology* / Q000601:surgery; D008159:Lumbar Vertebrae / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000601:surgery; D013123:Spinal Fusion / Q000379:methods