What is Artificial Disc Replacement?
Artificial disc replacement (also known as total disc) surgery is one of the latest advancements in spine surgery. Replacing the disc removes the cause of pain while preserving natural motion. Total disc replacement is recommended only after extensive conservative therapies have failed to significantly provide pain relief. The surgeon makes an incision in the front of the neck. The contents of the neck are gently retracted, enabling the front part of the spine to be seen. Fluoroscopy is used to determine the correct level(s) before the disc material is removed and the artificial disc is inserted.
What is Disc Replacement?
Disc replacement, whether in the neck or the low back, consists of removing the disc which is the soft portion that joins the vertebral bodies at the front of the spine. In the past, fusions were carried out, in which a material or bone graft was placed in between the vertebral bodies to eliminate motion. The exact opposite happens when we carry out a disc replacement. A disc replacement is made of similar material as total hips and total knees, but the field is rapidly changing. There are newer materials that MRI compatible, which means that one can still obtain an MRI scan without resorting to the invasive diagnostic procedures where a needle and dye are placed into the spinal canal with a myelogram CAT scan. The other advancement has been in the development of a disc that acts more like our normal disc that will have some compressibility or shock absorption.
Longer term studies are showing that if you have disc replacement, maintaining motion of the operated level, that there is less of a chance of needing more surgery in the future, and this is reduced to approximately 3 to 4 times less than if one was to have a fusion. The problem with disc replacement today is that in the neck it is highly accepted by the insurance companies with the majority of them paying for a single level and now even two level disc replacements. This is because patients that suffer from disc problems complain of shoulder and arm pain and it becomes intolerable. The alternative is to do an anterior cervical fusion, which is a very successful operation as well. Unlike the neck, in the lumbar spine, while we have excellent long-term data now, since the year 2000, insurance companies are reluctant to pay for this. They do so because of the controversy surrounding surgery for low back pain. However, we are very careful in our selection process and the results of lumbar disc replacement have been extremely gratifying in allowing the patients, in the vast majority of cases, to an active life-style. The technology continues to improve, but we have been impressed that the even the first generation artificial disc continued to perform well. We now have 10-year follow-up of the lumbar disc and we are beginning to see early 10-year follow-up of the cervical disc, showing that they too, continue to function well for the patient. This is an area that will continue to evolve and while all patients who suffer from conditions of the cervical or lumbar spine may be candidates for fusion, there are a significant number then that are candidates for disc replacement.
The advantages of disc replacement are the lessened changes at the levels above and below, that is what we call adjacent level disc disease, requiring surgery. This is one quarter to one-third less compared to fusion at 10 years. In other words, if you have a fusion you have a 30 percent chance of having more surgery at a level above or below, whereas, if you have a disc replacement, it is 25% to one-third the rate as if you have had a fusion.
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