Study: Overall success rates favor nonconstrained cervical disc replacement over ACDF

NEW ORLEANS — 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 clinical outcomes and secondary surgery rates compared to anterior cervical discectomy and fusion with allografts and plates.

“This study supports that the PCM Cervical Disc [NuVasive] 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 at the North American Spine Society Annual Meeting. “At 5 years, patients with a PCM had a statistically high mean reduction from baseline in [neck disability index] NDI and a statistically high rate of NDI success. Although not presented, these differences did meet minimal clinically important differences.”

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.

“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 the time period or [sort] of a slight degradation in NDI success in the ACDF when we started getting to 5 years,” Phillips said. “Neurologic success and rate of second surgeries were similar between the groups. Overall success favored PCM, but the rates were not statistically significantly different for those two parameters.”

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.

The range of motion at 5 years was 5.3° in the PCM group and 0.5° in the ACDF cohort. About 90% of patients in both groups had successful neurologic outcomes at 5 years, Phillips said. Reoperation rates were 7.9% and 7.4%, respectively.

Reference:

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

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.