Cervical Disc Replacement at 20 Years: Benchmarking Revision Rates and Refining Patient Selection

For years, spine surgeons could tell patients how often hip and knee replacements fail. They could not do the same for cervical disc replacement (search)Search drug. That changed with a 2024 study from Texas Back InstituteView company profile, which analyzed 1,626 consecutive cervical disc replacement patients treated between 2003 and June 2021 and found an implant removal or revision rate of 1.48%. Since publication, the series has expanded to more than 2,200 patients, with updated findings presented at scientific meetings.

"There are good benchmarks in hip and knee replacements," said Scott Blumenthal, MD, a spine surgeon at Texas Back InstituteView company profile in Plano. "We looked at our database and asked: What do we tell our patients is the chance to require revision of your cervical disc replacement (search)Search drug, because everybody's doing them now?"

The finding does more than provide reassurance for patients. It gives spine surgeons something the field has historically lacked: a long-term benchmark.

What causes a cervical disc replacement (search)Search drug 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 (search)Search disease, 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.

"Osteolysis (search)Search disease seems to occur more commonly with two of the FDA-approved discs in the U.S.," Dr. Blumenthal 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 One of those devices was the M6 disc (search)Search drug, which has since been withdrawn from the U.S. market.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," he added.

Outside of osteolysis (search)Search disease, most revision procedures stemmed from technical factors, including 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," Dr. Blumenthal said. "Not doing a sufficient posterior decompression is a common cause of revision."

The osteolysis (search)Search disease 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.

Fusion is not always the answer for revision

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 (search)Search disease disrupts that end plate, so those cases seem to be more appropriate for fusion," Dr. Blumenthal 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 adjacent-level disease (search)Search disease question

When Daniel Riew, MD, began implanting artificial cervical discs in 2002, surgeons hoped preserving motion would prevent the levels above and below from deteriorating. More than two decades later, Dr. Riew, chief of cervical spine surgery at Columbia University, believes that promise has not held.

"We thought, 'If we do this, there will be no more adjacent-level disease (search)Search disease,'" Dr. Riew said. "That was kind of naive."

Dr. Riew and his colleagues found a statistically significant difference in adjacent-level reoperation between disc replacement and fusion in longer-term data, but the benefit was far smaller than originally anticipated—roughly 4 percentage points at 10 years in their analysis. Artificial discs may reduce the risk. They do not stop the clock.

"The answer is because people get old," Dr. Riew said. "When you operate at one level, you have to understand that all of the discs are exactly the same age." A 50-year-old patient does not have one aging disc and several young ones. Every segment has experienced the same five decades.

What the operation actually offers

If cervical disc replacement (search)Search drug does not dramatically protect neighboring levels, why has it continued gaining momentum? "It has withstood the test of time," Dr. Riew said. "The long-term data is as good as a fusion."

Patients in the early FDA trials often recovered quickly, avoided cervical collars, and returned to normal activities sooner. Dr. Riew said he allows most artificial disc patients to return to work and recreational activities such as golf, tennis, and pickleball almost immediately. Fusion patients face a different recovery. Although some surgeons do not use a postoperative collar after ACDF, Dr. Riew routinely does, believing that limiting motion improves the speed and reliability of healing.

The amount of motion preserved at one level may be modest. Dr. Riew said most patients would struggle to distinguish the range of motion produced by a one-level disc replacement from that of a one-level fusion. The value becomes more noticeable as the number of treated levels increases. Losing one motion segment may be imperceptible. Losing three can change how the neck feels and functions.

The critical importance of patient selection

The growing popularity of cervical disc replacement (search)Search drug has created a new risk: treating the operation as inherently preferable to fusion. Dr. Riew does not. "A nail doesn't fit every job," he said.

Patients with extensive bone spurs, ossification of the posterior longitudinal ligament, or diffuse idiopathic skeletal hyperostosis may continue forming bone around a motion-preserving implant. If the surgeon cannot fully remove the compressive pathology through the disc space, symptoms can recur. "The patient would have been much better off having an ACDF to begin with," Dr. Riew said.

Bone quality presents another dividing line. Artificial discs rely on the vertebral endplates for support. In patients with osteoporosis or significant osteopenia, the implant can subside into weakened bone, collapse the disc space, and create deformity. Dr. Riew said he has revised several patients whose implants collapsed, and in some, the damage was extensive enough to require a corpectomy. He believes surgeons should evaluate bone quality before cervical disc replacement (search)Search drug using a DEXA scan, CT imaging, or Hounsfield unit measurements.

A normal DEXA result may not tell the entire story. Bone density varies across the cervical spine, and the commonly operated C6-7 level may have lower density than more central cervical vertebrae.

The size of the spinal canal also matters. A patient born with an unusually narrow canal may not do well with disc replacement even after the disc is removed, as continued motion can cause the ligamentum flavum to buckle inward, recreating compression over time. Myelomalacia (search)Search disease raises an additional concern, as implanting an artificial disc often requires tapping the device into place—force that could further injure an already compromised cord.

The hybrid surgery dilemma

The most difficult cervical cases do not always call for choosing entirely between fusion and disc replacement. A patient with disease at several levels may have one segment well suited to arthroplasty and another that requires fusion. Dr. Riew believes hybrid procedures are particularly valuable in three- and four-level disease, where multilevel ACDF carries a substantial risk of pseudarthrosis (search)Search disease.

"It saves the insurance company money," Dr. Riew said. "It's better for the patient because they don't lose four motion segments, and in the end, everybody wins."

Yet some insurers still do not cover a fusion and artificial disc during the same operation. That leaves surgeons with choices that may be worse for both the patient and the payer. "It would be much better for patients if insurance would allow hybrid operations," Dr. Riew said.

A maturing field

For Dr. Blumenthal, the most important contribution of the revision study may not be the 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 (search)Search target, 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."

After two decades of cervical disc replacement (search)Search drug, the field is no longer asking whether the procedure works. It is asking how to make an already durable operation even better—and, as Dr. Riew emphasizes, knowing exactly where motion belongs and where it does not.