title: Comparison of Clinical Outcomes of 1- and 2-Level Total Disc Replacement: Four-Year Results From a Prospective, Randomized, Controlled, Multicenter IDE Clinical Trial.
abstract: METHODS
  A prospective, randomized, multicenter Food and Drug Administration Investigation Device Exemption study using total disc replacement as surgical treatment of degenerative disc disease at 1 or 2 contiguous levels of the cervical spine.
  
  
  OBJECTIVE
  To evaluate the safety and effectiveness of total disc replacement at single or 2 contiguous levels through 48 months of follow-up.
  
  
  BACKGROUND
  Cervical total disc replacement has been shown to be a safe and effective alternative to anterior cervical discectomy and fusion at 24 months. Its motion-preserving capabilities may avoid accelerating adjacent segment pathology and thereby lower the rate of associated complications.
  
  
  METHODS
  Patients were randomized in a 2:1 ratio (total disc replacement [TDR]: anterior cervical discectomy and fusion [ACDF]) at 24 sites. Ultimately, 164 patients received TDR at 1 level and 225 patients received TDR at 2 contiguous levels. An additional 24 patients (15 one-level, 9 two-level) were treated with TDR as training cases.Outcome measures included neck disability index, visual analogue scale neck and arm pain, Short Form 12-item Health Survey (SF-12) Mental Composite Score (MCS) and Physical Composite Score (PCS), range of motion, major complication rates, and secondary surgery rates. Patients received follow-up examinations at regular intervals through 4 years after surgery.
  
  
  RESULTS
  Preoperative characteristics were statistically similar for the 1- and 2-level patient groups. Four-year follow-up rates were 83.1% (1-level) and 89.0% (2-level). There was no statistically significant difference between 1- and 2-level TDR groups for all clinical outcome measures. Both TDR groups experienced significant improvement at each follow-up when compared with preoperative scores. One case of migration was reported in the 2-level TDR group.
  
  
  CONCLUSIONS
  A 4-year post hoc comparison of 1- and 2-level TDR patients concurrently enrolled in a 24-center, Food and Drug Administration Investigation Device Exemption clinical trial indicated no statistical differences between groups in clinical outcomes, overall complication rates, and subsequent surgery rates.
  
  
  METHODS
  1.
authors.affiliation: *Cedars-Sinai Spine Center, Los Angeles, CA †Department of Neurological Surgery, University of California, Davis, Sacramento, CA ‡Spine Institute of Louisiana, Shreveport, LA §Orange County Neurosurgical Associates, Laguna Hills, CA ¶Texas Back Institute, Plano, TX ‖Greater Baltimore Neurosurgical Associates, Baltimore, MD **Orthopaedics Northeast, Fort Wayne, IN ††Oklahoma Spine & Brain Institute, Tulsa, OK ‡‡Precision Spine Care, Tyler, TX §§Austin Brain & Spine, Austin, TX ¶¶Seton Spine & Scoliosis Center, Austin, TX; and ‖‖The Core Institute, Phoenix, AZ.
authors.forename: Hyun W
authors.initials: HW
authors.lastname: Bae
authors.forename: Kee D
authors.initials: KD
authors.lastname: Kim
authors.forename: Pierce Dalton
authors.initials: PD
authors.lastname: Nunley
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Jackson
authors.forename: Michael S
authors.initials: MS
authors.lastname: Hisey
authors.forename: Reginald J
authors.initials: RJ
authors.lastname: Davis
authors.forename: Gregory A
authors.initials: GA
authors.lastname: Hoffman
authors.forename: Steven E
authors.initials: SE
authors.lastname: Gaede
authors.forename: Guy O
authors.initials: GO
authors.lastname: Danielson
authors.forename: Daniel L
authors.initials: DL
authors.lastname: Peterson
authors.forename: John M
authors.initials: JM
authors.lastname: Stokes
authors.forename: Ali
authors.initials: A
authors.lastname: Araghi
mesh_terms: D002574:Cervical Vertebrae / Q000000981:diagnostic imaging; D004185:Disability Evaluation; D005500:Follow-Up Studies; D006801:Humans; D055959:Intervertebral Disc Degeneration / Q000150:complications / Q000503:physiopathology / Q000601:surgery*; D019547:Neck Pain / Q000209:etiology; D010147:Pain Measurement; D017060:Patient Satisfaction; D011446:Prospective Studies; D011843:Radiculopathy / Q000150:complications; D011859:Radiography; D016059:Range of Motion, Articular; D012086:Reoperation; D016037:Single-Blind Method; D059145:Total Disc Replacement / Q000009:adverse effects / Q000295:instrumentation