When talking about artificial disc replacement it is important to recognize that there is a huge difference between lumbar disc replacement (low back) and cervical disc replacement (neck).
Many spine surgeons are more cautious about lumbar disc replacement than cervical disc replacement for the following reasons:
- In the lumbar area, a surgeon must access the FRONT of the spine by going through the abdomen and working around internal organs to reach the front of the spine to install the artificial disc. In the neck the surgeon has easy access to the front of the neck.
- The lumbar disc must withstand the weight of the trunk while the cervical disc only needs to support the weight of the head.
- If the mechanical disc wears out, it will require revision surgery which is much more complex in the lumbar area than the neck.
Also in the lumbar area, the early pioneering lumbar discs which were used for years in Europe more than 20 years ago, did not perform as well as some thought. Naturally, with the demands placed on lumbar discs, and the complex surgery involved for installation and revision surgery, many spine surgeons have cautious.
Mobi-C® Artificial Disc. ©LDR Spine, USA Inc.
Conversely artificial discs for the neck have been better received. They were first approved by the FDA in 2017 and the technology has progressed dramatically over the last 13 years.
Concerns about the early cervical artificial discs caused many surgeons to be cautious. Similarly, health insurance companies are typically skeptical of any new technology. That is changing quickly as more research documents that artificial disc can provide great advantages over spinal fusion.
This is especially the case in the neck where there are only 6 spinal discs (with the vertebrae labeled C-1 to C-7), compared to 17 below that in the thoracic and lumbar spine. The thoracic vertebra are labeled with a T and the lumbar vertebrae are labeled with an L.
A herniated disc in the neck, if fused, can put more stress on the remaining 5 discs and potentially causing herniations at the other levels. If 2 of the 6 disc levels are fused, the person would have little ability to rotate their neck.
Consequently, there has been great effort by artificial disc companies to get their disc approved by the FDA for 2 levels. This enables the spine surgeon to maintain nearly the same natural rotation of the normal healthy disc in the neck.
Selecting the right disc for you
The spine surgeon needs to perform a thorough assessment of your specific case to determine if you even qualify for artificial disc replacement. There are many considerations related to your disc herniation, the location, severity, presence of bone spurs, even your age.
The indications for disc replacement may vary for each type of artificial disc.
Typically, if the pain symptom appears to be coming from the disc, and it has not responded to non-surgical treatment, including drugs, therapy, manipulation/manual therapy or spinal injections, that may indicate you are a candidate for artificial disc replacement.
Some spine surgeons may order diagnostic tests like a discogram to verify the exact disc level that is causing the pain symptom. The worst case scenario would be to operate on the wrong disc level. Consequently, such diagnostic tests are to confirm the disc level to increase the success of the surgery at eliminating pain symptoms.
There are several artificial discs for the neck, the most popular being the Prestige, M6, Prodisc and Mobi-C.
The spine surgeon will often use different discs to address a patient’s anatomic issues such as the slope angle of the vertebrae, etc. The patient’s age, and the type of activity they hope to return to (e.g. golf, tennis, skiing) may all affect the type of artificial disc the surgeon recommends.
Consequently, a spine surgeon may use one disc at one level and a different disc for another level for the optimal bio-mechanical result.
It’s also important to understand that the artificial discs that are FDA approved have typically gone through rigorous clinical studies comparing the clinical outcome against traditional fusion treatment, or no treatment at all. For example, it can cost close to $50 million for a spinal implant company to do an FDA trial.
The restrictive review and approval process in place in the United States is far more rigorous than in Europe, South Africa and Australia where devices are approved more quickly with less study.