title: Symptomatic adjacent segment disease after cervical total disc replacement: re-examining the clinical and radiological evidence with established criteria.
abstract: BACKGROUND
  Although several publications in the last decade have proved equality in safety and efficacy of the total disc replacement (TDR) to the anterior fusion procedure in cervical spine, the claim that TDR may reduce the incidence of adjacent segment disease (ASD) has not been corroborated by clinical evidence.
  
  
  OBJECTIVE
  We attempt to predict the true incidence of symptomatic ASD after TDR surgery in the cervical spine at one or two levels at a median follow-up period of 4 years.
  
  
  METHODS
  A total of 763 patients were screened to participate in four different Food and Drug Administration device exemption trials for artificial cervical disc replacement at three collaborating institutions. Two hundred seventy-one patients qualified and enrolled in the trials. One hundred seventy-three randomized to receive artificial disc replacement surgery, and 167 have completed a 4-year or longer follow-up.
  
  
  METHODS
  Patients experiencing cervical radiculopathy symptoms in the follow-up period were worked-up with clinical examinations, magnetic resonance imaging of the cervical spine, and other diagnostic studies. Once a clinical correlation was established with the imaging evidence of adjacent segment degeneration, a careful record was maintained to document the subsequent medical and/or surgical treatment received by these patients. Statistical analysis was performed to determine the true incidence of and factors affecting the ASD after cervical disc replacement in these patients.
  
  
  RESULTS
  Twenty-six patients (15.2%) were identified to satisfy our criteria for ASD at the median follow-up of 51 months, with the annual incidence of 3.1% as calculated by life tables. The actuarial 5-year freedom from ASD rate was 71.6%±0.6%, and the mean period for freedom from ASD was 70.4±2.1 months.
  
  
  CONCLUSIONS
  The incidence of symptomatic ASD after cervical TDR is 3.1% annually regardless of the patient's age, sex, smoking habits, and design of the TDR device. The presence of osteopenia and lumbar degenerative disease significantly increase the risk of developing ASD after anterior cervical surgery.
authors: Spine Institute of Louisiana, 1500 Line Ave., Ste 200, Shreveport, LA 71115, USA.
authors: Pierce D
authors: PD
authors: Nunley
authors: Ajay
authors: A
authors: Jawahar
authors: David A
authors: DA
authors: Cavanaugh
authors: Charles R
authors: CR
authors: Gordon
authors: Eubulus J
authors: EJ
authors: Kerr
authors: Phillip Andrew
authors: PA
authors: Utter
mesh_terms: D000328:Adult; D000368:Aged; D001851:Bone Diseases, Metabolic / Q000453:epidemiology; D002574:Cervical Vertebrae / Q000473:pathology* / Q000601:surgery*; D016208:Databases, Factual / Q000706:statistics & numerical data; D018572:Disease-Free Survival; D017586:Diskectomy / Q000009:adverse effects; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D055959:Intervertebral Disc Degeneration / Q000453:epidemiology; D053208:Kaplan-Meier Estimate; D008159:Lumbar Vertebrae / Q000473:pathology; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000453:epidemiology*; D011237:Predictive Value of Tests; D011843:Radiculopathy / Q000453:epidemiology; D016032:Randomized Controlled Trials as Topic; D012307:Risk Factors; D059145:Total Disc Replacement / Q000009:adverse effects*