title: ProDisc artificial total lumbar disc replacement: introduction and early results from the United States clinical trial.
abstract: METHODS
  Multicenter prospective randomized study of artificial disc replacement (ProDisc) versus circumferential fusion (standard of care) for one- and two-level degenerative disc disease. This is an interim analysis on patients seen at the Spine Institute Saint John's Health Center, Santa Monica, California.
  
  
  OBJECTIVE
  To evaluate early pain and functional outcomes of patients treated with disc replacement or fusion and to assess the capacity of this intervertebral disc replacement for preserving motion in the lumbar spine.
  
  
  BACKGROUND
  Disc replacement is intended to reduce pain via removal of the diseased disc while restoring physiologic motion and height at the affected level. The long-term physiologic advantage of disc replacement to fusion is that preservation of motion may prevent additional degeneration at adjacent levels.
  
  
  METHODS
  Patients meeting inclusion criteria were consented for study. Randomization was performed using a 2 to 1 ratio of disc replacement procedure to a fusion procedure. Patients rated their pain on the Visual Analogue Scale and completed the Oswestry Disability Index questionnaire. Radiographs were taken. Assessments were made before surgery and after surgery at 6 weeks, 3 months, 6 months, and 1 year (ongoing). Changes from preoperative pain, disability, or motion were separately evaluated as a function of treatment using repeated measures mixed design analysis of variance.
  
  
  RESULTS
  This analysis includes data up to 6 months from the first 53 randomized patients. There were 35 patients who underwent disc replacements, and 18 patients had fusion procedures. Disc replacement patients had a significant reduction in pain and disability at earlier evaluations. By 6 months, the relative improvement on both the Visual Analogue Scale and Oswestry (both, P < 0.05) were similar for disc replacement and fusion patients. Greater motion was found at L4-L5 for disc replacement patients (P < 0.05) than fusion patients. A similar trend was noted at L5-S1 (P was not significant).
  
  
  CONCLUSIONS
  Disc replacement patients reported significantly less pain (Visual Analogue Scale) and disability (Oswestry) in the early period following surgery compared to fusion patients. This difference disappeared by 6 months. When compared to fusion, the disc replacement allowed preservation of motion at L4-L5 with a similar trend at L5-S1.
authors.affiliation: The Spine Institute at Saint John's Health Center, Santa Monica, California 90404, USA. rdelamarter@espineinstitue.com
authors.forename: Rick B
authors.initials: RB
authors.lastname: Delamarter
authors.forename: David M
authors.initials: DM
authors.lastname: Fribourg
authors.forename: Linda E A
authors.initials: LE
authors.lastname: Kanim
authors.forename: Hyun
authors.initials: H
authors.lastname: Bae
mesh_terms: D000328:Adult; D019643:Arthroplasty, Replacement / Q000295:instrumentation* / Q000379:methods; D004864:Equipment and Supplies; D005260:Female; D006801:Humans; D007405:Intervertebral Disc Displacement / Q000150:complications / Q000601:surgery*; D017116:Low Back Pain / Q000209:etiology / Q000601:surgery; D008159:Lumbar Vertebrae / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D013123:Spinal Fusion; D016896:Treatment Outcome; D014481:United States