title: Prospective, randomized, multicenter Food and Drug Administration investigational device exemption study of the ProDisc-L total disc replacement compared with circumferential arthrodesis for the treatment of two-level lumbar degenerative disc disease: results at twenty-four months.
abstract: BACKGROUND
  Disc replacement arthroplasty previously has been shown to be an effective alternative to spine fusion for the treatment of single-level lumbar degenerative disc disease. The purpose of the present study was to determine the twenty-four-month results of a clinical trial of the ProDisc-L total disc replacement as compared with spinal fusion for the treatment of degenerative disc disease at two contiguous vertebral levels from L3 to S1.
  
  
  METHODS
  A total of 237 patients were treated in a randomized controlled trial designed as a non-inferiority study for regulatory application purposes. Blocked randomization was performed with use of a 2:1 ratio of total disc arthroplasty to circumferential arthrodesis. Evaluations, including patient self-assessments, physical and neurological examinations, and radiographic examinations, were performed preoperatively, six weeks postoperatively, and three, six, twelve, eighteen, and twenty-four months postoperatively.
  
  
  RESULTS
  At twenty-four months, 58.8% (eighty-seven) of 148 patients in the total disc replacement group were classified as a statistical success, compared with 47.8% (thirty-two) of sixty-seven patients in the arthrodesis group; non-inferiority was demonstrated. The mean Oswestry Disability Index in both groups significantly improved from baseline (p < 0.0001); the mean percentage improvement for the total disc replacement group was significantly better than that for the arthrodesis group (p = 0.0282). An established clinical criterion for success, a ≥15-point improvement in the Oswestry Disability Index from baseline, occurred in 73.2% (109) of 149 patients in the total disc replacement group and 59.7% (thirty-seven) of sixty-two patients in the arthrodesis group. The Short Form-36 physical component scores were significantly better for the total disc replacement group as compared with the arthrodesis group (p = 0.0141 at twenty-four months). Visual analog scale scores for satisfaction significantly favored total disc replacement from three to twenty-four months. At twenty-four months, 78.2% (111) of 142 patients in the total disc replacement group and 62.1% (thirty-six) of fifty-eight patients in the arthrodesis group responded "yes" when asked if they would have the same surgery again. Lumbar spine range of motion on radiographs averaged 7.8° at the superior disc and 6.2° at the inferior disc in patients with total disc replacement. Reduction in narcotics usage significantly favored the total disc replacement group at twenty-four months after surgery (p = 0.0020).
  
  
  CONCLUSIONS
  Despite the relatively short duration of follow-up and design limitations, the present study suggests that two-level lumbar disc arthroplasty is an alternative to and offers clinical advantages in terms of pain relief and functional recovery in comparison with arthrodesis. Longer-term follow-up is needed to determine the risks for implant wear and/or degenerative segment changes.
authors.affiliation: The Spine Institute at Saint John's Health Center, 1301 20th Street, Suite 400, Santa Monica, CA 90404, USA.
authors.forename: Rick
authors.initials: R
authors.lastname: Delamarter
authors.forename: Jack E
authors.initials: JE
authors.lastname: Zigler
authors.forename: Richard A
authors.initials: RA
authors.lastname: Balderston
authors.forename: Frank P
authors.initials: FP
authors.lastname: Cammisa
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Goldstein
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Spivak
mesh_terms: D000328:Adult; D019643:Arthroplasty, Replacement / Q000295:instrumentation*; D018795:Device Approval; D004185:Disability Evaluation; D005260:Female; D006801:Humans; D007403:Intervertebral Disc; D055959:Intervertebral Disc Degeneration / Q000150:complications / Q000601:surgery*; D017116:Low Back Pain / Q000209:etiology / Q000601:surgery*; D008159:Lumbar Vertebrae / Q000601:surgery*; D008297:Male; D010147:Pain Measurement; D017060:Patient Satisfaction; D011183:Postoperative Complications; D011446:Prospective Studies; D019736:Prostheses and Implants; D011474:Prosthesis Design; D016059:Range of Motion, Articular; D020127:Recovery of Function; D013123:Spinal Fusion / Q000295:instrumentation; D018709:Statistics, Nonparametric; D016896:Treatment Outcome; D014481:United States; D014486:United States Food and Drug Administration