What’s the Claim?
Analysis of a large statewide database in New York compared single-level cervical disc replacement to anterior cervical discectomy and fusion for radiculopathy and/or myelopathy, and found:
- No overall difference in terms of survivorship (defined as revision at the level operated on or an adjacent level) at a minimum of 5 years after surgery
- That finding held up (no differences between the approaches) when a variety of potential confounding variables were controlled for
- A trivial difference (< 1 day) in length of stay favored disc replacement, but a higher percentage of patients in that group developed dysphagia after surgery
How’s It Stack Up?
Studies on this topic have been all over the map, as you know. A CORRelations post on this topic a few months back wrote, “[e]arlier studies related to the FDA’s approval process of these devices (which now have intermediate- to long-term follow-up) favored cervical disc arthroplasty, while a number of more-recent RCTs, which now also are out 5 to 10 years, did not.” This study from a large state registry supports and complements those RCTs. And that’s important. Randomized trials provide a detailed look — outcomes scores and patients’ results — in very-well-matched patient groups, but they don’t always generalize well; they’re usually performed by a small group of surgeons at a few centers. Registry studies, like the current one, tell us how something’s performing in the real world. This one, for example, draws from an all-payer data reporting system in a large state, and contained over 7000 of these procedures. A key concern is whether the indications for the interventions in question differed; there’s no way to know for sure, but there weren’t large or obvious differences (though ACDF was performed in the overwhelming majority of patients, nearly 90%). The most-important difference was that the disc replacement group was about four years younger than the ACDF group. And like any registry study, revisions performed outside the registry — in this case, outside of New York — would be lost, though there is no reason to think that would happen more in one group than the other here.
What’s Our Take?
We’re naturally a little cautious of paradigm-shifting surgical approaches and implants, since — particularly in arthroplasty — they have only inconsistently delivered on their promise. Until a new tool, in this case, disc replacement, shows clear advantages, we’ll naturally tilt toward a better-tested (and in this case less-expensive) alternative. For single-level cervical radiculopathy or myelopathy, other than in very specific circumstances, that alternative is ACDF. The design rationale for cervical disc replacement was to decrease adjacent-segment degeneration resulting in reoperation when compared to the alternative of fusion. At least at 5- to 10-year follow-up, in this generalizable (statewide) sample, that goal was not achieved.
Paek S, Zelenty WD, Dodo Y,et al. Up to 10-year Surveillance Comparison of Survivability in Single-level Cervical Disc Replacement Versus Anterior Cervical Discectomy and Fusion in New York. J Neurosurg Spine. 2023;39:206-215.