Outcomes with cervical disc replacement device maintained through 7 years

CHICAGO — Segmental motion in the cervical spine was maintained through 84 months of follow-up in patients who underwent cervical disc replacement with a low-profile prosthesis, according to results presented at the North American Spine Society Annual Meeting.

“Positive outcomes have been maintained through 7 years. Initially studies on cervical arthroplasty demonstrated significant clinical benefit, but no one knew the duration of those benefits. Now we can safely say the clinical benefit of cervical arthroplasty remains strong through 7 years. This is important information because the study speaks for the long-term for value of cervical arthroplasty,” Matthew F. Gornet, MD, told Spine Surgery Today.

Patients who underwent cervical disc replacement (CDR) received the Prestige LP Disc (Medtronic). Investigators used the Neck Disability Index (NDI), Neck and Arm Pain Numerical Rating Scales, SF-36 and other parameters as outcome measures and compared 211 investigational patients and 182 historical controls who underwent anterior discectomy and fusion (ACDF).

CDR overall success

Patients who underwent CDR in this study exhibited a statistical improvement in overall success (74.9%) compared to patients in the ACDF group (63.2%), according to the abstract.

In addition, patients saw statistical improvements in NDI, Neck and Arm Pain Numerical Rating Scale and SF-36 scores at 1.5-months post-surgery, which were maintained through the 84-month follow-up. Furthermore, the results showed patients in the CDR group maintained 6.9° mean angular motion at the targeted level at the 84-month follow-up.

“The maintenance of overall success superiority, with a lower number of second surgeries at the index level compared to fusion, continues to demonstrate a positive difference between arthroplasty and fusion over time,” Gornet said.

Return to work statistics

The groups were statistically similar preoperatively. There were differences postoperatively, however, in other parameters, such as median return to work (RTW). The median RTW was 40 days in the CDR group and 60 days in the ACDF group.

“That has a huge impact on cost overall. If you are off work essentially 33% less, 40 days vs. 60 days return to work, it is a huge impact on cost not only for the employers, but cost for society and costs for the individual patient. To me, these data from the trial are significant,” Gornet said.

HO causes must be understood

Gornet and colleagues noted that among areas that need further study with this device are it use in two-level cases and the impact on outcomes of heterotopic ossification (HO) and bridging bone.

“We do not fully understand what is causing HO, and there seem to be different HO rates for different prostheses. This lack of clarity on HO confounds our ability to separate fusion with arthroplasty and determine the true benefit of arthroplasty vs. fusion. Studying and having a better understanding of HO will help us answer that question and may lead us to different designs and different materials that may help prevent HO,” Gornet said.

No statistical differences between the two groups in the rate of serious device or device/procedure-related adverse events were reported in the patients studied, he said.

Gornet said the researchers are currently conducting 10-year follow up with these patients. – by Susan M. Rapp and Robert Linnehan

Reference:
Gornet MF, et al. Paper #91. Presented at: North American Spine Society Annual Meeting; Oct. 14-17, 2015; Chicago.

For more information:
Matthew F. Gornet, MD, can be reached at The Orthopedic Center of St. Louis, 14825 N. Outer Forty Rd., Suite 200, Chesterfield, MO 63017; email: fschranck@spirittresearch.com.

Disclosure: Gornet reports he receives royalties from Pioneer and Medtronic and has stock ownership in Bonovo, Oruoboros, International Spine & Orthopedic Institute, Nocimed and Paradigm Spine.