title: Estimating the risk for symptomatic adjacent segment degeneration after lumbar fusion: analysis from a cohort of patients undergoing revision surgery.
abstract: OBJECTIVE
  Aim of this study is to estimate the risk for symptomatic adjacent segment degeneration (ASD) and examine the association between spino-pelvic parameters and ASD.
  
  
  METHODS
  22 patients operated upon by instrumented lumbar or lumbosacral spinal fusion and re-operated upon for ASD were enrolled in the study. 83 consecutive patients with the same surgery and never re-operated upon were the controls. Pelvic incidence, sacral slope (SS), pelvic tilt (PT), and lumbar lordosis were calculated.
  
  
  RESULTS
  Patients with ASD had significantly lower SS (p = 0.005) and higher PT values (p < 0.001). Patients with SS <39° or PT >21°, were at higher risk for symptomatic ASD (relative risk 1.73 for SS and 3.663 for PT).
  
  
  CONCLUSIONS
  In patients re-operated upon for ASD, pelvic retroversion and hyperlordosis are the main mechanisms of compensation for the unbalanced spine. Patients with PT above 21° and SS below 39° are at higher risk for symptomatic ASD.
authors.affiliation: Department of Orthopaedics and Trauma Surgery, Center of Integrated Research, CIR, University Campus Bio-Medico of Rome, Via Alvaro del Portillo, 200, 00128, Rome, Italy, dimartino.cbm@gmail.com.
authors.forename: Alberto
authors.initials: A
authors.lastname: Di Martino
authors.forename: Carlo Cosimo
authors.initials: CC
authors.lastname: Quattrocchi
authors.forename: Laura
authors.initials: L
authors.lastname: Scarciolla
authors.forename: Nicola
authors.initials: N
authors.lastname: Papapietro
authors.forename: Bruno
authors.initials: B
authors.lastname: Beomonte Zobel
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Denaro
mesh_terms: D000328:Adult; D000368:Aged; D015331:Cohort Studies; D005260:Female; D006801:Humans; D055959:Intervertebral Disc Degeneration / Q000209:etiology / Q000601:surgery*; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D010384:Pelvic Bones / Q000000981:diagnostic imaging / Q000601:surgery; D011859:Radiography; D012086:Reoperation; D012189:Retrospective Studies; D012307:Risk Factors; D012447:Sacrum / Q000000981:diagnostic imaging / Q000601:surgery; D013123:Spinal Fusion / Q000009:adverse effects*