People with painful, unstable necks from degenerative disease have two surgical options when conservative (nonoperative) care fails to help. The first is still considered the gold standard (preferred choice) : anterior cervical discectomy and fusion or ACDF. The second is a total disc arthroplasty or disc replacement.
There are several reasons why surgeons even started looking for an alternative treatment approach to replace ACDF. ACDF had been around since the 1950s. Disc implants have been around for about 10 years now, so we are starting to get some study results with long-term outcomes.
However, more than half a century of data on ACDF has shown us that despite improvements in the procedure, patients still have problems. There is measurable increased pressure on the remaining discs. Degenerative disease (called adjacent segment degeneration or ASD) on either side of the fusion site is common. Patients end up having a second surgery more often than expected.
Other problems develop after neck fusion such as stiffness, nonunion of the bone, and broken hardware (plates, screws, pins) used to aid the fusion process. Complications of the surgery can also include difficulty swallowing or speaking due to nerve damage.
In the early part of the 21st century (2002), European surgeons started using cervical arthroplasty devices. A year later, the United States Food and Drug Administration (FDA) approved the use of these implants on a trial basis. Three separate implants are now available on the market: the Bryan Cervical Disc System, the Prestige-ST Cervical Disc, and the ProDisc-C.
Studies published so far show that disc replacements (also referred to as implant devices) provide equal results to cervical (neck) fusion in terms of pain relief and function. Studies comparing these two treatment approaches providing data up to five years after surgery, show that patients in both groups continue to report high levels of satisfaction.
With either surgery (fusion or replacement), there are potential problems. Bone bridging needed to complete the fusion or to hold the disc implant in place doesn’t always happen. The absence of bone bridging across the surgical site is called nonunion. Post-operative complications and problems are still reported with either procedure. These can include difficulty swallowing, swelling, neck pain, and the need for another (second or revision) surgery.
In the case of disc implantation, the device can sink down into the bone (called subsidence). When this happens, the affected neck segment may lose motion and the patient may experience painful symptoms. Disc devices can also break or shift out of position. But when the disc replacement works well, it does maintain neck motion, which is something a fusion eliminates.
At the present time, researchers conclude by saying that disc replacements provide just as good, if not better, results compared with the “gold standard” of spine fusion. Certainly, patients with disc replacements do no worse than those with a neck fusion.
Surgeons say they expect in time that the value and benefit of disc replacement will be proven. They predict better outcomes than with neck fusion and better motion with less chance of developing adjacent segment disease. And the risk of reoperation will remain significantly lower compared with neck fusion.