Safety and Effectiveness of Two-level Total Disc Replacement (TDR) versus Two-level Anterior Cervical Discectomy and Fusion (ACDF)

Meeting Highlight from NASS 2014

EfficacyDuring the North American Spine Society's 29th Annual Meeting, Dr. Reginald J. Davis presented results of a study of the safety and effectiveness of 2-level total disc replacement (TDR) compared to an anterior cervical discectomy and fusion (ACDF) control group. The title of the study is Two-level Treatment with Total Disc Replacement versus ACDF: Results from a Prospective Randomized Clinical trial with Five Years Follow-up.

Although several TDR devices are on the market, few have been clinically evaluated for 2-level use. In this prospective, randomized, controlled, multicenter (24 sites) trial, Mobi-C® (LDR Spine, Austin, Texas) was the investigational device. The control was ACDF with allograft and anterior plate and screws.

Study Summary
The study included 330 patients randomized 2:1. Inclusion criteria included diagnosis of symptomatic cervical degenerative disc disease at two levels (C3-C7), unresponsive to non-operative treatment(s), and no previous history of cervical fusion surgery.

  • 2-level TDR: 225 patients
  • 2-level ACDF: 105 patients

Dr. Davis explained, "Our hypothesis was these TDR patients will continue to demonstrate superiority compared to ACDF in 2 years, to what is now 5 years of follow-up." Furthermore, he said, "Patient follow-up was robust. At the beginning, 95 with 89% and even after 5 years, 91% of the TDR and 87% of the ACDF patients were still available for evaluation."

Outcome Measures
Extensive outcome measures included:

  • Neck Disability Index (NDI)
  • Visual Analogue Scale (VAS)
  • Range of motion
  • Patient satisfaction
  • SF-12 Physical and Mental Health Composite Scores (PCS, MCS)
  • Major complications
  • Subsequent surgery rate
  • Overall success rate

Dr. Davis stated, "The mean NDI scores … and substantial improvement in both groups. And I can't emphasize that enough, the ACDF is an excellent operation. However, at every time frame, there was a statistically significant better outcome with TDR versus ACDF, and this is as true at 5 months as it was at 2 years."

  • Return to work: The patients who received TDR returned to work more quickly—46 days versus 67 days.
  • Arm pain: The patients who received TDR had better recovery of arm function with less pain.
  • Range of motion: ACDF eliminates motion at the superior and inferior levels. TDR preserves range of motion, which was still apparent at 5 years.
  • Patient satisfaction: Very high for both the TDR and ACDF groups. However, at 5 years, the patient satisfaction rate was statistically better in the TDR group.
  • SF-12 PCS and MCS: In the mental component, the results for both groups were similar. However, in the physical component, patient satisfaction was statistically greater among the patients who received TDR.
  • Major complications/adverse events: Near the 5 year follow-up point, the TDR group experienced fewer major complications and adverse events.
  • Subsequent surgery: "When we look at subsequent surgeries at the index levels there were -statistically significant- fewer subsequent surgeries for the TDR versus ACDF at 3.8% versus 16.2%, respectively," stated Dr. Davis.

Concluding Comments by Reginald J. Davis
"This is the first long-term clinical evidence from an FDA IDE trial on 2-level patients. The follow-up rates were the highest of any study at this level at this time: TDR followup at 90.7% and ACDF followup at 86.7%."

  • Mobi-C® patients maintained segmental range of motion through 5 years compared to the ACDF patients.
  • Two-level Mobi-C® patients experienced statistically significant benefits over ACDF patients at 60 months (eg, NDI, VAS scores).
  • "Overall study success rates demonstrated that Mobi-C® at two contiguous levels should be a superior alternative to ACDF through 5 years."
Updated on: 08/18/16
Continue Reading
Physician Burnout and Professional Dissatisfaction Linked to Electronic Health Records and Computerized Physician Order Entry

Get new patient cases delivered to your inbox

Sign up for our healthcare professional eNewsletter, SpineMonitor.
Sign Up!