An alternative to the traditional surgery of discectomy and fusion for cervical disc herniations is Cervical Total Disc Replacement. The development of artificial cervical discs is intended to accomplish the same objectives as the traditional decompression and fusion surgery in terms of providing pain relief and stability, but with fewer drawbacks. For example, the cervical artificial disc does not include the potential complications involved with using bone graft (e.g. ‘non-unions’) and theoretically should lessen the risk of developing adjacent-segment disc degeneration or disease by maintaining the normal motion between the vertebrae.
The artificial disc is designed to take the place of the real intervertebral disc and be placed between two vertebral bodies where the disc has been surgically removed in order to decompress the spinal cord or nerve root in the neck. Ideally the artificial disc acts like a normal disc, providing motion while acting as a shock absorber in the spine (unlike a fusion, which eliminates both motion and shock absorption in the fused segment of the spine). Generally, the recovery period after total disc replacement surgery is faster, allowing patients to return to normal activities earlier than after a fusion.
Many total disc replacement surgeries can be performed on an out-patient / ambulatory basis allowing the patient to return home the same day.
There are a variety of artificial discs that are approved by the United States Food and Drug Administration (FDA) through clinical trials. All technologies share similar goals of replacing the original disc, but differ in their designs and materials.
Types of Cervical Artificial Discs
There are a number of artificial cervical discs currently available in the US.
- One general artificial disc design comprises metal endplates with an intervening low friction polymer (plastic) to allow for motion between the polished metal surface and the polymer. Currently two different polymers are in clinical evaluation:
- Metal and Polyethylene devices: These are the same materials that are used for total hip and knee arthroplasties, and have been shown to have no ill effects on the body in long term studies. Examples of this type of technology include:
- Prodisc-C™ by Synthes Spine Solutions
- Secure-C™ by Globus Medical Inc.
- Mobi-C™ by LDR
- Metal and Polyurethane device: This comprises application of a softer polymer intended to provide not only motion, but shock absorption closer to the human cervical disc:
- Bryan™ Cervical Disc Prosthesis by Medtronic Sofamor Danek
- Metal and Polyethylene devices: These are the same materials that are used for total hip and knee arthroplasties, and have been shown to have no ill effects on the body in long term studies. Examples of this type of technology include:
- Another disc replacement design uses a metal-on-metal joint to mimic normal motion at the cervical disc space. Examples of this type of technology include:
- Prestige-LP™ cervical disc by Medtronic Sofamor Danek •
All these discs have demonstrated excellent results in clinical trials comparing disc replacement to fusion surgery. The strengths and limitations of all these technologies will be better understood with the passage of time and further study.