Artificial Disc Replacement Remains More Hype Than Reality

Updated January 23, 2024

If you read this blog, you know that I often write about things I experience on a day-to-day basis while seeing patients. This past week a patient came in with a herniated disc in her neck and was offered an artificial disc as a treatment. After a short discussion, she no longer wanted one. What did I say? That artificial discs remain more hype than scientific reality. Let’s dive in.

The Promise

The idea behind artificial discs was simple. Instead of a fusion that stops all motion, a device could be implanted which still allowed the segment to move. Given that we know that fusing the level solid with bone and hardware causes adjacent segment disease, at face value, this made some sense. However, the reality turned out to be something different.

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My Patient

This nice young woman had been diagnosed with a disc herniation at C5-C6 on the right which was causing neck pain and symptoms down that arm into the biceps. Those symptoms were no longer severe, but a local surgeon had offered her an Artificial Disc Replacement (ADR). This was in and of itself bizarre, as the standard of care today would have been at least trying and failing a steroid epidural before a big neck surgery. In addition, she was sold the surgical song and dance that they were simply replacing a bad disc with a device, so she would be as good as new. Let’s explore that concept.

Is an ADR Even a Valid Treatment for a Herniated Disc?

ADRs were designed to be used in patients whose natural disc has collapsed and become degenerative and who were otherwise fusion candidates. Was this woman a neck fusion candidate? Nope. If she was a surgical candidate at all, she was a discectomy candidate where the surgeon would remove the herniated disc material and perhaps add a small laminectomy. I can find no clinical publications or guidelines that claim that an ADR device can be used in her specific case of a herniated disc in the neck. The nuttier part was that the surgeon’s office somehow got the insurer to approve the surgery!

Is an ADR Better than a Fusion?

I’ve reviewed the research on ADR use in the neck before. In 2022, the data was clear, ADRs didn’t work. However, this is still a relatively new technology, so has more data been published and has that changed?

The research that exists on this topic is becoming more and more focused. For example, basic science research shows that the way an artificial disc moves doesn’t mimic the normal movement of a disc (1). On the clinical side, high-level meta-analyses show that we can’t prove that ADR is any better than fusion when causing ASD (2). There is also a Swedish registry study that shows no difference between ADR and fusion (3).

I found two Randomized Controlled Trials (RCTs). A brand new study looking at an RCT comparing fusion to ADR shows no difference in ASD rates (4). There’s also a 5-year RCT that shows no difference as well (5).

The only large review I can find that concludes the opposite was authored by a surgeon who received almost half a million USD from device companies making these devices (6). Smaller positive studies published on specific devices like Pro-Disc have issues.

The upshot? The saying “there is no such thing as a free lunch” seems to apply here to ADR devices. Meaning the non-device manufacturer-sponsored research continues to show that while a good idea on paper, these devices don’t work any better than a fusion. Hence, if I was a patient considering an ADR, I would avoid the hype!

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References:

(1) Wachowski MM, Weiland J, Wagner M, Gezzi R, Kubein-Meesenburg D, Nägerl H. Kinematics of cervical segments C5/C6 in axial rotation before and after total disc arthroplasty. Eur Spine J. 2017 Sep;26(9):2425-2433. doi: 10.1007/s00586-017-5073-z. Epub 2017 Apr 4. PMID: 28378073.

(2) Yang X, Janssen T, Arts MP, Peul WC, Vleggeert-Lankamp CLA. Radiological follow-up after implanting cervical disc prosthesis in anterior discectomy: a systematic review. Spine J. 2018 Sep;18(9):1678-1693. doi: 10.1016/j.spinee.2018.04.021. Epub 2018 May 8. PMID: 29751126.

(3) MacDowall A, Skeppholm M, Lindhagen L, Robinson Y, Löfgren H, Michaëlsson K, Olerud C. Artificial disc replacement versus fusion in patients with cervical degenerative disc disease with radiculopathy: 5-year outcomes from the National Swedish Spine Register. J Neurosurg Spine. 2018 Nov 2;30(2):159-167. doi: 10.3171/2018.7.SPINE18657. PMID: 30485205.

(4) Goedmakers CMW, de Vries F, Bosscher L, Peul WC, Arts MP, Vleggeert-Lankamp CLA. Long-term results of the NECK trial-implanting a disc prosthesis after cervical anterior discectomy cannot prevent adjacent segment disease: five-year clinical follow-up of a double-blinded randomised controlled trial. Spine J. 2023 Mar;23(3):350-360. doi: 10.1016/j.spinee.2022.11.006. Epub 2022 Nov 15. PMID: 36396007.

(5) MacDowall A, Canto Moreira N, Marques C, Skeppholm M, Lindhagen L, Robinson Y, Löfgren H, Michaëlsson K, Olerud C. Artificial disc replacement versus fusion in patients with cervical degenerative disc disease and radiculopathy: a randomized controlled trial with 5-year outcomes. J Neurosurg Spine. 2019 Jan 11;30(3):323-331. doi: 10.3171/2018.9.SPINE18659. PMID: 30641852.

(6) Chang CC, Huang WC, Wu JC, Mummaneni PV. The Option of Motion Preservation in Cervical Spondylosis: Cervical Disc Arthroplasty Update. Neurospine. 2018 Dec;15(4):296-305. doi: 10.14245/ns.1836186.093. Epub 2018 Dec 14. PMID: 30545210; PMCID: PMC6347355.

Originally published on Jan 22, 2024