A relatively new surgical procedure in which a damaged disc is replaced – similar to the replacement of a knee or hip.

What is an artificial disc?

The disc is the soft cushioning structure located between the individual bones of the spine, called “vertebra.” It is made of cartilage-like tissue and consists of an outer portion, called the annulus, and an inner portion, called the nucleus. In most cases, the disc is flexible enough to allow the spine to bend

An artificial disc (also called a disc replacement, disc prosthesis or spine arthroplasty device) is a device that is implanted into the spine to imitate the functions of a normal disc (carry load and allow motion).

There are many artificial disc designs classified into two general types: total disc replacement and disc nucleus replacement. As the names imply, with a total disc replacement, all or most of the disc tissue is removed and a replacement device is implanted into the space between the vertebra. With a disc nucleus replacement, only the center of the disc (the nucleus) is removed and replaced with an implant. The outer part of the disc (the annulus) is not removed.

Artificial discs are usually made of metal or plastic-like (biopolymer) materials, or a combination of the two. These materials have been used in the body for many years. Total disc replacements have been used in Europe since the late 1980s. The most commonly used total disc replacement designs have two plates. One attaches to the vertebrae above the disc being replaced and the other to the vertebrae below. Some devices have a soft, compressible plastic-like piece between these plates. The devices allow motion by smooth, usually curved, surfaces sliding across each other.

Most nucleus replacement devices are made of plastic-like (biopolymer) materials. One such material is called hydrogel. This material expands as it absorbs water. The device is placed into the nuclear cavity of the disc and hydrates to expand and fill the cavity. The device is compressible and by this means, allows motion, much like a normal disc nucleus. Another design consists of a piece of a plastic-like material that coils around to fill the nuclear cavity There are also disc replacements designed for use in the cervical spine (the neck). These devices have only been used a relatively short time,

Who needs an artificial disc?

The indications for disc replacement may vary for each type of implant. Some general indications are pain arising from the disc that has not been adequately reduced with non-operative care such as medication, injections, chiropractic care and/or physical therapy. Typically, you will have had an MRI that shows disc degeneration. Often discography is performed to verify which disc(s), if any, is related to your pain. (Discography is a procedure in which dye is injected into the disc and X-rays and a CT scan are taken. See the NASS Patient Education brochure on Discography for more information.) The surgeon will correlate the results of these tests with findings from your history and physical examination to help determine the source of your pain.

There are several conditions that may prevent you from receiving a disc replacement. These include spondylolisthesis (the slipping of one vertebral body across a lower one), osteoporosis, vertebral body fracture, allergy to the materials in the device, spinal tumor, spinal infection, morbid obesity, significant changes of the facet joints (joints in the back portion of the spine), pregnancy, chronic steroid use or autoimmune problems. Also, total disc replacements are designed to be implanted from an anterior approach (through the abdomen). You may be excluded from receiving and artificial disc if you previously had abdominal surgery or if the condition of the blood vessels in front of your spine increases the risk of significant injury during this type of spinal surgery.

Back pain is sometimes produced by an injured or degenerated disc. To treat this condition, alternatives to disc replacement include fusion, non operative care or no treatment. Typically, surgery is not considered for disc-related pain unless the pain has been severe for a prolonged period (typically over six months) and the patient has gone through nonoperative treatments (such as active physical therapy, medication, injections, activity modification and/or spinal manipulation).