Cervical artificial disc replacement has come about after lumbar artificial discs were FDA approved back in 2004. The neck implants were FDA approved around 2008. The idea is to preserve motion, since spinal fusions weld bones together and send the stresses that used to be absorbed above and below. This can create adjacent level problems post-operatively. The neck implant is designed to replace a damaged or diseases intervertebral disc in the neck. This can be seen with degenerative disc disease, a herniated cervical disc, or maybe a post-traumatic issue.
This disc problem then creates a situation where pinched nerves occur. Nerves may be pinched directly from disc material that has extruded into an area where it's not supposed to be. Or with a degenerative disc height in the disc space is lost to such an extent that nerves are compressed indirectly as they try to exit from the spine.
The neck artificial disc surgery is done with a surgical approach through the front area (just off to the side) of the neck. Neck muscles are not split, but separated from each other, making the post-operative pain very tolerable in most cases.
Once the spine is reached, a device is put in to keep the esophagus, vessels, and musculature to the sides and the complete diseased disc is then removed. Once the complete disc is remove, the vertebral bodies are spared except for some shaping that needs to be done to accept the implant.
Instruments are used to size for the cervical disc replacement, and then the metallic implant with a plastic spacer is implanted. There are a few different kinds of neck disc replacements, with some being "press-fit" while others actually have a screw above and below into the bone to keep it more stable. A real time x-ray machine, called fluouroscopy, is used to make sure the implant is centered properly. This is key, as it is important to have the implanted centered to try as best as possible to recreate physiologic range of motion.
Patients usually leave the hospital within 24 hours and the pain relief and complication profiles have shown similarity to regular neck fusions.
Cervical disc replacements have shown equivalency so far to cervical fusions. Cervical fusions from the front have been an extremely successful operation by and large with over a 95% success rate. Cervical disc replacements cost more however, so long term studies are necessary to see if the cost benefit is present when compared to clinical outcomes.
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