Study: Motion preservation at two cervical levels may make more sense than ACDF

At 5 years after surgery, investigators found no statistically significant difference in efficacy between one-level and two-level treatment with ACDF or CTDR.

SAN FRANCISCO — The safety and effectiveness of cervical total disc replacement was maintained at 5-year follow-up at levels seen in studies of the same prosthesis with shorter follow-up, and this was the case regardless of whether the prosthesis was implanted at one or two levels of the spine, according to study data presented here.

Results of one-level anterior cervical discectomy and fusion (ACDF) were comparable to those of one- and two-level cervical total disc replacement (CTDR) in the 5-year results, but not to those of two-level ACDF, according to Hyun W. Bae, MD, of Santa Monica, Calif., who presented the study results at the North American Spine Society Annual Meeting.

Hyun W. Bae

The prospective, randomized, multicenter, concurrently controlled trial comprised two treatment arms. The study involved physicians at 24 U.S. centers and now has follow-up to 5 years. The CTDR implant used was the Mobi-C prosthesis (LDR Medical; Troyes, France).

Two hundred forty-five patients were enrolled in the one-level procedure arm of the study, where they were randomly assigned in a 2:1 fashion to either CTDR (164 patients) or ACDF (81 patients). The study’s two-level arm included 330 patients randomly assigned in a 2:1 fashion to either CTDR (225 patients) or ACDF (105 patients).

Randomized with 5-year follow-up

“Of note, at 5 years, our follow-up rate was 88.5% in the CTDR group and 83.1% in the ACDF group,” Bae said.

Bae and colleagues used multiple measures to assess the outcomes of both procedures performed in the one-level and two-level settings, including function according to the Neck Disability Index (NDI), neck and arm pain, patient satisfaction with the procedure, complications, reoperations and other factors.

NDI results through 36 months

NDI scores, which reflected the patients’ functional result showed that one-level CTDR and one-level fusion were about equivalent, as was two-level CTDR, according to Bae.

“However, at 24 and 36 months a statistically significant difference is observed with two-level fusion,” he said.

Functional outcomes with the two-level ACDF appeared to drop off as the follow-up reached closer to 5 years, based on the findings.

“Two-level fusion does seem to be a different operation in terms of function,” Bae said, noting in some respects that two-level fusions lagged behind the other three procedures.

Less satisfaction with 2-level ACDF

“Although, if you look it as a whole, all of these operations are very good, meaning that they still rank with a 90% satisfaction rate,” Bae said, but he mentioned there was a trend toward less patient satisfaction with two-level ACDF.

The results showed relatively low rates of complications and adverse events of about 5% or less for the three most successful procedures studied — one-level CTDR, one-level ACDF and two-level CTDR.

At mid-term and long-term follow-up, these results changed very little, according to Bae.

“This study really looks at ACDF as a historical control,” he said. “I think we all believe in ACDF and it certainly is a good operation, but the study really looks at what happens when you start getting into multi-level fusions and what they can cost.” – by Susan M. Rapp

Reference:

Bae HW. Paper #80. Presented at: North American Spine Society Annual Meeting. Nov. 12-15, 2014; San Francisco.

For more information:

Hyun W. Bae, MD, can be reached at The Spine Institute, 2811 Wilshire Blvd., Suite 850, Santa Monica, CA 90403; email: baemd@me.com.

Disclosure: Bae receives royalties from Stryker, NuVasive, Zimmer, Biomet, has stock ownership in DiFusion, Spinal Restoration, and has private investments in Ascent, is a consultant to Stryker and has teaching/speaking arrangements with Synthes.