Overall success rates favor nonconstrained cervical disc replacement over ACDF

At 5 years after treatment, patients in the cervical disc replacement cohort obtained 5.3° range of motion.

The 5-year results of an investigational device exemption study found a nonconstrained cervical disc device had a higher rate of success using the Neck Disability Index and similar neurological improvements and secondary surgery rates compared to anterior cervical discectomy and fusion with allografts and plates.

“This study supports that the PCM Cervical Disc [NuVasive Inc., San Diego] maintained motion and continued to achieve clinical outcomes at least equivalent to [anterior cervical discectomy and fusion] ACDF out to 5 years,” Frank M. Phillips, MD, said in a presentation of the study results. “At 5 years, patients with a PCM had a statistically high mean reduction from baseline in [neck disability index] NDI and a statistically higher rate of NDI success. Although not presented, these differences did meet minimal clinically important differences.”

Frank M. Phillips

The prospective randomized study included adult patients with single-level degenerative disease who were unresponsive to 6 weeks of conservative care. There were 160 patients in the PCM group and 124 patients in the ACDF cohort. He said the trial included patients who had a previous single-level fusion at an adjacent level.

NDI to gauge improvement

“The NDI measures were either stable or improved for PCM when compared to the 3-, 4- and ultimately 5-year results; whereas in the control group, they were about the same over time period,” Phillips said at the meeting. “Overall success favored PCM while neurologic success and rate of second surgery were similar between the groups,” he said.

The mean NDI score at 5 years was 20 points for the PCM group and 28 points for the ACDF group. The investigators found the mean reduction in NDI scores from baseline was 34 points for the PCM group vs. 26.8 points for the ACDF cohort. NDI success, defined as at least 20% improvement, was found in 85% of the PCM group vs. 74% of the ACDF group at 5 years.

Preoperative and postoperative films of a 34 year-old male with radicular symptoms and a soft disc herniation at C6-7 who underwent PCM (NuVasive) CDR.

Images: Phillips FM

A look ahead

“Cervical total disc replacement has been proven to be a well established treatment for cervical degenerative pathologies with outcomes that equal or exceed those reported for anterior cervical discectomy and fusion,” Phillips told Spine Surgery Today. “Future research will focus on the long-term durability of these results,” he said.

At 5 years, the range of motion at the treated level was 5.3° in the PCM group and 0.5° in the ACDF cohort and about 90% of patients in both groups had successful neurologic outcomes, Phillips said. Reoperation rates were 7.9% and 7.4%, respectively. – by Gina Brockenbrough, MA, and Susan M. Rapp

Reference:

Phillips FM. Paper #181. Presented at: North American Spine Society Annual Meeting; Oct. 9-12, 2013; New Orleans.

For more information:

Frank M. Phillips, MD, can be reached at Rush University Medical Center, Midwest Orthopaedics, 1725 W. Harrison St., Suite 1063, Chicago, IL 60612; email: frank.phillips@rushortho.com.
Disclosure: Phillips receives royalties from NuVasive, DePuy, a Johnson & Johnson Company, Stryker and Kyphon; is a paid consultant for NuVasive; has stock or stock options in NuVasive, Spinal Kinetics, Spinal Motion, Axiomed, Flexuspine, CrossTrees, Pearl Diver, Facet Solutions, Pioneer, Vital 5 and SI Bone.