IDE trial shows similar pain reduction with intervertebral disc vs. fusion at 1 year

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By Gina Brockenbrough
August 20, 2008

Early results show that cervical disc replacement using a metal-on-metal intervertebral device that couples axial rotation and distraction may provide similar pain relief to anterior cervical discectomy and fusion.

As part of a U.S. Food and Drug Administration investigational device exemption (IDE) trial, Jeffrey S. Fischgrund, MD, and colleagues compared the results of subset of 92 patients with cervical radiculopathy symptoms who were treated with either the CerviCore Intervertebral Disc (Stryker Spine) or anterior cervical discectomy and fusion (ACDF) at four U.S. centers.

A 1-year follow-up of 65 patients revealed a decrease in the mean preoperative Visual Analog Scale (VAS) scores for neck pain and patients' initially worse arm pain for both groups and a drop in the percentage of patients taking pain medication.

"What we have here are improvements from preoperative [scores] in the Neck Disability Index and VAS, decreased pain management and return to work," Fischgrund said during his presentation at Spine Week 2008. "At 1 year, I think that it is clear that the CerviCore patients are similar to the fusion patients."

Technique
The investigators studied a subset of patients participating in an ongoing trial involving 25 centers with 400 patients. The prospective, randomized trial includes patients with cervical radicular symptoms at one level from C3 to C7 and excludes those with axial neck pain alone.

Patients randomized to the arthroplasty group received a cobalt-chromium-molybdenum alloy intervertebral disc that features a titanium plasma spray coating and fixation spikes.

"The unique feature about this device is that with rotation, you get axial distraction, which may help with foraminal opening and hopefully less radicular pain. This is obviously the reason why we are operating," Fischgrund said. "Additionally, to mimic cervical spine mechanics, the center of rotation is below the device during flexion and extension and is above the device during lateral motion."

Surgeons only have to slightly modify their technique to implant the device, he said. "The biggest difference is you need to mark the midline with some type of marker using fluoroscopy. Once you put your Caspar pins in, the rest of the procedure will key off these. Really, the hardest part of the procedure is making sure that you get these pins in the midline."

Operative time
In their subset of patients, the investigators found similar demographics between the groups, but greater operative time for the arthroplasty group. "I suspect that this will go down with time, but there is a little bit of extra time involved in the beginning with the fluoroscopy," Fischgrund said.

The investigators discovered that the mean neck pain scores improved 50 points from preop to 1-year postop for the arthroplasty group and 46 points for the fusion group. The mean arm pain for the initially worse arm also improved 59 points from preop to 12-months postoperative in the arthroplasty group and improved 50 points in the fusion group.

In addition, the study showed that 85% of patients in the arthroplasty group used pain medication preoperatively compared to 44% at 1-year postop. Similarly, 80% of the fusion group used pain medication preoperatively vs. 47% at 1-year follow-up.

"What is remarkable is that these patients get this motion back very quickly and maintain it almost immediately postoperatively to the 12-month time frame," Fischgrund said.

The arthroplasty group had 8.3° flexion/extension and 6° of lateral bending, while the fusion group had 1.3° flexion/extension and 1.6° of lateral bending at 12 months, he said.

For more information:

Jeffrey S. Fischgrund, MD, can be reached at 27207 Lasher Road, Suite 200B, Southfield, MI 48034; 248-663-1907; e-mail: jsfischgrund@comcast.net. He is a consultant for Stryker and the company sponsored this study.

Reference:

Fischgrund J, Garcia R, Gratch M, et al. Cervicore disc replacement vs. fusion: Results from four study sites in a prospective, randomized, multicenter trial. Paper #AB5. Presented at Spine Week 2008. May 26-31, 2008. Geneva.