For years, spine surgeons could tell patients how often hip and knee replacements fail. They could not do the same for cervical disc replacement.
The procedure has grown rapidly over the last two decades, with hundreds of thousands of implants placed worldwide and increasing adoption across the United States. Yet one of the most basic patient questions remained surprisingly difficult to answer.
What are the chances the device will eventually need to be revised or removed?
Scott Blumenthal, MD, a spine surgeon at Texas Back Institute in Plano, set out to find an answer.
“There are good benchmarks in hip and knee replacements,” Dr. Blumenthal said. “We looked at our database and asked: What do we tell our patients is the chance to require revision of your cervical disc replacement, because everybody’s doing them now?”
The result was one of the largest revision analyses in cervical arthroplasty to date.
A 2024 study of 1,626 consecutive cervical disc replacement patients treated between 2003 and June 2021 found an implant removal or revision rate of 1.48%. Since publication, the Texas Back Institute series has expanded to more than 2,200 patients, with updated findings presented at scientific meetings but not yet published.
The finding does more than provide reassurance for patients. It gives spine surgeons something the field has historically lacked: a long-term benchmark.
A field growing up
According to Dr. Blumenthal, cervical disc replacement is beginning to enter the same phase of development that hip and knee replacement reached years ago. Early research focused on whether the procedure worked. The next phase focuses on understanding why the small number of failures occur.
“We’ve created a literature, at least the beginning of the literature, much like our orthopedic colleagues,” Dr. Blumenthal said. “We’re doing papers on revision cervical arthroplasty, not just first timers.” That distinction is important.
For decades, cervical arthroplasty research concentrated on proving that motion-preserving surgery could safely compete with fusion. Now that long-term outcomes have become established, researchers are increasingly studying the uncommon cases where things go wrong. For Dr. Blumenthal, that evolution represents a sign of maturity rather than concern.
What causes a cervical disc replacement to fail?
Among a separate series of 53 revision cases published in 2024 — a group that has since expanded to 77 patients — the leading cause of revision was osteolysis, a process in which bone is gradually resorbed around the implant.
The finding surprised many surgeons because osteolysis has not historically been considered one of the dominant concerns in cervical arthroplasty. Dr. Blumenthal believes the issue may be related to specific implant designs rather than the procedure itself. “Osteolysis seems to occur more commonly with two of the FDA-approved discs in the U.S.,” he said. “That may be just an early finding, but it does seem to focus on two of the discs.”
One of those devices was the M6 disc, which has since been withdrawn from the U.S. market. Another was a PEKK-based ceramic implant that appears to demonstrate a higher incidence of osteolysis than traditional cobalt-chrome and polyethylene devices.
“The alternate-material discs seem to have a higher incidence,” Dr. Blumenthal said. Outside of osteolysis, most revision procedures stemmed from technical factors. Those included patient selection issues, implant sizing problems and inadequate decompression during the initial surgery.
“You have to take the bad disc out, you have to unpinch the spinal cord and nerves, and then you put in the disc,” he said. “Not doing a sufficient posterior decompression is a common cause of revision.”
Fusion isn’t always the answer
One of the most important questions surrounding revision cervical arthroplasty is whether a failed implant automatically requires fusion. According to Dr. Blumenthal, the answer is no.
Among the 53 revision cases, 16 patients underwent another disc replacement while 36 were converted to fusion. The deciding factor is often the condition of the vertebral end plate. “Severe osteolysis disrupts that end plate, so those cases seem to be more appropriate for fusion,” he said. “Whereas some of the technical issues, like a disc that slips out of place or an oversized disc, preserve the end plate, so we can just do a different, properly sized disc.”
Overall, roughly one-third of failed cervical disc replacements can be revised with another arthroplasty procedure, while the remainder require fusion because of bone loss or structural damage.
The next questions researchers are asking
For Dr. Blumenthal, the most important contribution of the study may not be the revision rate itself. It is the ability to ask more sophisticated questions. Large databases allow researchers to examine whether certain implant designs are associated with specific failure modes, whether particular patient characteristics increase risk and whether long-term surveillance protocols should be adjusted.
One area of ongoing investigation involves Cutibacterium acnes, a bacteria frequently identified on spinal implants. Researchers still do not know whether the organism contributes to implant failure or simply exists as a bystander.
“We’re not sure if that’s really a pathogen or whether it’s just kind of along for the ride,” Dr. Blumenthal said. “That question has not been answered.”
The osteolysis timeline is also becoming clearer. Most cases appear between five and seven years after implantation, although the earliest presentations can occur within two to three years.That information may help surgeons identify appropriate surveillance windows and counsel patients about long-term follow-up. As cervical arthroplasty continues to expand, Dr. Blumenthal believes surgeons entering the field should focus on mastering fundamentals before pushing indications.
“Pick your disc, pick your patient and then learn the technique really well,” he said. “The first patient you should do should not be an older patient with a lot of arthritic changes in the disc. It should be a younger patient with a soft disc herniation. That’s the low-hanging fruit, and that’s where you should start.”
For patients, the message is equally straightforward. The risk of revision appears low.
But perhaps more importantly, spine surgeons are finally accumulating the long-term data needed to understand the small number of failures that do occur.
After two decades of cervical disc replacement, the field is no longer asking whether the procedure works. It is asking how to make an already durable operation even better.
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