title: Prevalence of adjacent segment degeneration after spine surgery: a systematic review and meta-analysis.
abstract: METHODS
  Systematic review of published prevalence of adjacent segment degeneration (ASD) after spine surgery.
  
  
  OBJECTIVE
  To evaluate the prevalence of ASD in patients after cervical and lumbar spine surgery.
  
  
  BACKGROUND
  ASD is a common complication after spine surgery in long-term follow-up. A large body of literature has been reported on the topic, but no meta-analysis of the epidemiological data on ASD has been published
  
  
  METHODS
  We searched the MEDLINE until March 2012 published in English language that reported the prevalence of ASD after spine surgery. We determined the ASD rates by calculating proportions and 95% confidence interval (CI) for each study and then pooled the data to derive a pooled proportion and 95% CI.
  
  
  RESULTS
  A total of 94 studies with 34,716 patients from 19 countries were included. The occurrence of radiograph ASD ranged from 4.8% to 92.2%, and the pooled prevalence was 29.3% (95% CI, 22.7%-35.8%) by the random-effects model. The occurrence of symptoms ASD ranged from 0.0% to 30.3%, and the pooled prevalence was 7.4% (95% CI, 6.4%-8.5%). In cervical position, the occurrence of radiograph ASD and symptoms ASD was 32.8% (95% CI, 17.8%-47.9%) and 6.3% (95% CI, 4.8%-7.8%); in lumbar position, the occurrence of radiograph ASD and symptoms ASD was 26.6% (95% CI, 21.3%-31.9%) and 8.5% (95% CI, 6.4%-10.7%). In the 0.5- to 2- or less, more than 2- to 5- or less, and more than 5- to 20- or less year diagnosis time, the radiograph ASD prevalence was 21.8% (16.0%-27.6%), 33.6% (21.8%-45.4%), and 37.4% (10.7%-64.1%), respectively; and the symptoms ASD prevalence was 6.5% (4.8%-8.1%), 12.1% (8.2%-16.0%), and 3.2% (2.5%-4.0%), respectively.
  
  
  CONCLUSIONS
  Spine surgery is associated with significant risk of ASD. These figures may be useful in the estimation of the burden of the ASD after spine surgery.
authors.affiliation: Department of Orthopaedics, Traditional Chinese Medical Hospital of Nantong City, Nantong, Jiangsu, China. pphss@126.com
authors.forename: Xiao-Peng
authors.initials: XP
authors.lastname: Xia
authors.forename: Hong-Lin
authors.initials: HL
authors.lastname: Chen
authors.forename: Hong-Bin
authors.initials: HB
authors.lastname: Cheng
mesh_terms: D002574:Cervical Vertebrae / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D018572:Disease-Free Survival; D016021:Epidemiologic Studies; D006801:Humans; D055959:Intervertebral Disc Degeneration / Q000000981:diagnostic imaging / Q000453:epidemiology* / Q000209:etiology / Q000601:surgery; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D011183:Postoperative Complications / Q000453:epidemiology* / Q000209:etiology; D015995:Prevalence; D017594:Publication Bias; D011859:Radiography; D012107:Research Design; D012680:Sensitivity and Specificity; D013123:Spinal Fusion / Q000009:adverse effects*; D013314:Stress, Mechanical; D059145:Total Disc Replacement / Q000009:adverse effects*