10-year Follow-Up Cervical Disc Arthroplasty Data (Level 1)

How much more Level 1 evidence do insurers require?

Disc arthroplasty is one of THE most studied spinal implants in history.

Now comes another (!) ten-year follow up study. This Level 1 study covers 155 patients—a NOT insignificant amount of work over more than a decade—and is fully described in the study, “Cervical Disc Arthroplasty vs Anterior Cervical Discectomy and Fusion at 10 Years: Results From a Prospective, Randomized Clinical Trial at 3 Sites,” in the April 2023 edition of The International Journal of Spine Surgery.

Co-author Pierce Nunley, M.D., an orthopedic spine surgeon with the Spine Institute of Louisiana in Shreveport, who has participated in over 10 cervical total disc replacement trials as a principal investigator, provided a number of interesting and revealing details to OTW, “The FDA requires 2-year follow up—3-, 5- and 7-year studies are more frequent. However, 10-year studies are much rarer.”

“As we get further out, it becomes exponentially challenging to get follow up. However, true long-term results are needed to understand any technology; we endeavored to produce a 10-year abstract including the sites where the sponsor was willing to fund the follow up.”

With 155 patients enrolled (105 cervical disc arthroplasty; 50 anterior cervical discectomy and fusion [ACDF]), the researchers obtained follow-up from 78.1% of patients eligible after 7 years. The study device was the Mobi-C, a three-component artificial cervical disc for one- and two-level disc replacement.

At 10 years, cervical disc arthroplasty demonstrated superiority to ACDF: the composite success was 62.4% in cervical disc arthroplasty and 22.2% in ACDF. For cervical disc arthroplasty the cumulative risk of subsequent surgery at 10 years was 7.2%—for ACDF it was 25.5%.

The risk of adjacent-level surgery was 3.1% for cervical disc arthroplasty vs 20.5% for ACDF patients. The progression to radiographically significant adjacent-segment pathology at 10 years was 2/3^rd less in cervical disc arthroplasty vs ACDF (12.9% vs 39.3%).

At 10 years, patient-reported outcomes and change from baseline were generally better in cervical disc arthroplasty patients. A higher percentage of cervical disc arthroplasty patients reported they were “very satisfied” at the 10-year postoperative mark (98.7% vs 88.9%).

“The balance of cervical disc arthroplasty research has unequivocally led to the conclusion that cervical disc arthroplasty in appropriately selected and treated patients is not only as good as ACDF, but in many cases superior,” said Dr. Nunley to OTW. “This is generally regardless of which FDA approved device is selected if performed correctly.”

As for what might need to happen in order for surgeons to alter practice/move toward cervical disc arthroplasty, Dr. Nunley commented, “Education is important. I believe many surgeons still question the data. However, the lexicon has grown to the point where it really can’t be questioned as at least equivocal. Much of the data shows superiority in reoperation rates and symptomatic adjacent segment disease.”

“Training is also an issue. It is more difficult to successfully place a cervical disc arthroplasty vs perform an ACDF. It is appropriate for surgeons to be concerned if they are trained and have the appropriate skills. There are many avenues to obtain training and experience but that takes time, effort, and money.”

Yet…After Decades of Data…Insurers Still Reimburse More For ACDF…!?

“The biggest ‘elephant in the room’ is reimbursement,” stated Dr. Nunley to OTW. “Surgeons still get paid more for an ACDF than they do for a cervical disc arthroplasty. Also, the net profit for hospitals and ASCs are typically better for ACDF vs. cervical disc arthroplasty. If the reverse were true, I think we would see a significant shift in case selection.”

“The next issue we are looking at is, ‘What are the differences of the approved devices?’ Some companies have multiple devices. We know empirically that ‘one size doesn’t fit all,’ but we are way behind the hip and knee total joint development that has helped define technology regardless of which company developed it.”

“Most of the current research in cervical disc arthroplasty is funded by individual sponsors. Papers are written to support or attack different designs, but there have been no solid head-to-head studies funded. That being said, we are looking at some comparisons and currently have a couple of papers in the pipeline discussing this issue. We need to drill down into subtypes of patients and which of the available implants are better for different pathologies and which are not.”