At South Carolina Spine Center, Dr. Michael Kilburn currently uses two artificial disc technologies for the cervical spine (neck area):
1. The Bryan® cervical disc
2. The Mobi-C cervical disc
Artificial discs can be used for patients with herniated discs in the neck who would otherwise need a spinal fusion. With traditional spinal fusion surgeries, two vertebrae are “fused” together with a bone graft. While this retains the disc height after a damaged disc is removed, the fusion locks the two vertebrae together. Locking two segments can, in turn, put increased stress on the disc levels above and below as the neck rotates. Spine surgeons theorize that a fusion in the neck can cause additional disc herniation above and below the fusion site. This is called "adjacent segment disease.”
Spine surgeons and health insurance companies now commonly accept the use of artificial discs in the neck. The same cannot be said about the use of artificial discs in the lower back (lumbar spine). This is because the weight and stress placed on artificial discs in the trunk is far greater than the stress experienced in the neck area. Additionally, installation or removal of a lumbar disc is a more extensive surgery. Consequently, while artificial discs are implanted in the lower back, evolving artificial disc technology should be taken into account. Consequently, many spine surgeons may be cautious about the use of artificial discs in the lumbar area as technology continues to improve.
At South Carolina Spine Center, Dr. Michael Kilburn uses the Bryan® cervical disc and the Mobi-C artificial disc for certain patients with herniated discs in the neck who would otherwise need a spinal fusion. The surgeon’s selection of which disc is used is based on patient criteria. The Bryan® cervical disc features a polymer component with metal end plates.
For patients with two disc levels that are herniated because of degenerative disc disease, a spinal fusion of both levels can place extra stress on the remaining disc levels. Medical technology companies have focused on the development of artificial discs that can be installed at two levels in the neck. The Mobi-C® artificial disc, for example, is FDA approved for replacement of two levels in the neck, which can make it an ideal artificial disc choice for patients with disc herniations at two levels.
Traditionally, the common treatment for repairing herniated discs in the neck is an Anterior Cervical Discectomy and Fusion (ACDF) procedure. In a fusion surgery, the disc is removed and either a bone spacer or a plastic implant is placed to restore disc height and remove pressure on pinched nerves or the spinal cord. A metal plate and screws are then placed at the front of the neck to hold the implant in place. The result is a segment that no longer moves, or is “fused”.
In the lower back, because of the number of vertebrae, loss of movement is less of a problem as the remaining vertebrae can provide enough rotational movement. In the neck, however, there are fewer vertebral bones.
Over the past decade, several artificial discs for the neck have emerged and work well for single level disc herniations in the neck. However, none of these previous artificial discs addressed patients who might have disc degeneration at two levels.
Mobi-C® is the first and only cervical disc replacement device to receive FDA approval to treat both one-level and two-level cervical disc disease. Mobi-C® is different from other cervical discs because of its bone sparing technique, which eliminates the need for bone chiseling and drilling, and optimizes it for two-level applications.
“During artificial disc surgery, the surgeon must make room for the new implant that will replicate the movement and rotation of the original disc,” explains Dr. Kilburn. “This can involve some removal of the existing bone. The new Mobi-C® implant significantly reduces the amount of bone that is affected so you are preserving much more of the vertebral body.”
The main benefits of the artificial disc parallel that of knee and hip replacements. This can include the following:
When treating knee and hip replacement patients, orthopedic surgeons try to postpone the implantation of an artificial joint until a patient is at least 50 years old so that they do not outlive their artificial joint, which typically lasts anywhere from 15 to 20 years. Revision surgery, which may be necessary to replace a worn-out artificial joint, can be complex.
This is also a concern with any artificial disc. Unlike knee and hip replacement patients who are typically in their 50s or 60s, many patients can benefit from artificial disc technology at a much younger age — sometimes in their 20s or 30s. Therefore, the implantation of an artificial disc in younger patients can raise a concerns about the potential life span of the artificial disc in the spine and the need for revision surgery to replace a worn-out artificial disc.
In summary, some spine surgeons may be cautious about the use of artificial discs for the following reasons:
Generally, the technology is very promising. Your spine surgeon at South Carolina Spine Center can provide information if your problem can be addressed with this technology.