How an artificial disc works, successes and obstacles…

An artificial disc replacement is intended to duplicate the rotation of a normal, healthy disc and retain motion in the spine, which lessens the risk of herniation at the other disc levels. Artificial discs have been used in Europe since 1987. Because of the FDA’s approval process, artificial disc use in the U.S. did not begin until 2004.

Future development of new artificial discs attempt to not only mimic and reproduce the function of the normal disc by providing rotational movement but also up and down shock absorption.  Other issues in artificial disc design try to take into account the possibility of revision and replacement surgery if an artificial disc wears out over 10 to 20 years.

There is a big difference in the artificial discs used in the lumbar (low back) area, and the artificial discs used in the cervical (neck) area. Because of the weight of the body and the rotational stress that the trunk places on discs in the low back (lumbar) area, more stress is placed on artificial discs in the lumbar area than in the neck (cervical) area, which only supports the head.

A second issue relates to the ease of the artificial disc surgery and any necessary revision surgery to replace a worn out artificial disc. Because the surgeon must access the front of the spine, an incision is made in the abdomen for lumbar discs. This can require navigating around internal organs to access the discs at the front of the spine in the low back.

Conversely, the surgeon can easily access the cervical discs through a small incision in the front of the neck.

There are a variety of FDA-approved artificial discs available for the neck. However, the Medtronic Prestige LP and Mobi-C discs are the only ones currently approved by the FDA for use at two levels in the neck.  This can be of great benefit to those people with degenerative discs at more than one level in the neck and would otherwise need a fusion at the other level which in turn would restrict rotation.

With knee or hip joint replacement, surgeons try to postpone the implantation of an artificial joint until it is absolutely necessary so the patient does not outlive the artificial joint, which may last from 15 to 20 years.

But unlike knee and hip replacement patients, who are typically in their 50s or 60s when arthritis appears, many spine patients can benefit from artificial disc technology at a much younger age.

As with any artificial joint replacement, the earlier an artificial joint is implanted, the greater likelihood that it will need to be revised in the future because of normal wear and tear.

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