Something New and Important From an Original IDE RCT On Cervical Disc Arthroplasty

It took 20 years, but the finding about adjacent-segment degeneration finally turned up

What’s the Claim?

Perhaps the key goal of cervical disc arthroplasty (CDA) over anterior cervical discectomy and fusion (ACDF) is the preservation of motion, with the hope of avoiding subsequent adjacent-segment degeneration. But adjacent-segment degeneration doesn’t happen overnight; in fact, so far, some of the best evidence we’ve got on that question shows no advantage to CDA.

That just changed. We now have near-complete and true long-term follow-up — 20 years — from one of the early IDE randomized clinical trials on CDA. It found:

  • No differences between CDA and ACDF in terms of VAS arm pain, VAS neck pain, or Neck Disability Index (NDI) scores on their primary analyses (some post hoc slicing and dicing found some advantage to CDA, but we would not put a lot of stock in those findings)
  • Big differences favoring CDA in terms of reoperation (10% versus 42%)
    • All the reoperations in the ACDF group were for degeneration at another level, and most of them were adjacent-segment degeneration
  • CDA implant survival was 100%
    • The two reoperations in the CDA group were for degeneration at other levels

This is important news, but as always, context is key.

How’s It Stack Up?