Total disc replacement (TDR, also called artificial 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.
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.
Texas Back Institute was one of the pioneers in disc replacement, performing the very first one in March of 2000 in the lumbar spine. Since that time, we have participated in almost 14 different FDA trials of both cervical and lumbar disc. 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. At TBI; 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.
There are certain criteria that all patients must meet. By visiting with your spine surgeon, he/she can go over your history, look at your x-rays and determine if, indeed, you would be an appropriate candidate. In some cases additional tests might be needed, such as a CT scan or a bone density scan, which we at Texas Back Institute do routinely to make certain the bones are strong enough to hold the disc in the proper position without sinking into the bone.
All the artificial discs have to meet very strict standards from the FDA. They, in general, are tested to last 40 years in simulated testing. However, remember this is only in the laboratory and we do not have that long of a follow-up as of yet. In both the cervical and the lumbar spine; however, we now have good ten-year data in the US that shows that there is no reduction in the results; that is, if you have a good result by the time you reach 6 months, it is unlikely that you are going to have any significant problems in the future. Certainly, there can always be a problem from another level, but we have not seen the issues coming from the same levels. In fact, in looking at our thousands of patients that we have operated on, our revision rate at the level of surgery is only about 3%.
In the cervical spine it is almost immediate and this is often the case in the lumbar spine. Patients often wake up in the recovery room and notice that their pain is different. This is an excellent sign. If, however, with the lumbar disc replacement the pain is not totally gone right away, you should not worry, as we know that patients will continue to improve up till the first 6 months.
While unfortunately we are unable to repair the neck or the low back the way Mother Nature meant it to be, the artificial disc patients have done remarkably well and have the ability to return to their normal activities. After three months when the disc replacement is fixed to the spine, patients can then carry out any activity they wish. We have many examples of patients returning back to vigorous athletic activities, armed forces activities, mechanics, and professional athletes.
It is like any other procedure. You want to go to the experts where they have done more than anyone else. At Texas Back Institute, we have been the leaders in disc replacement and have performed over 3000 artificial disc to date. We’ve also participated in over a dozen FDA studies of the cervical and lumbar spine.
Unfortunately, not everyone is trained in the use of artificial disc. It is often easier to do another procedure, such as a fusion, if you have no experience. However, if you are candidate for a disc replacement and are younger, this is the ideal solution, rather than a fusion.
No. The devices are so relatively small and so deeply placed in the spine that we have not yet heard of a patient being stopped for this.
Yes. In the cervical spine there are several artificial discs that have been approved for two level use. In the lumbar spine, however, the FDA has only cleared single level use. It does not mean that it cannot be used in more than one or two levels, but this would be considered to be “off label” according to the FDA. It does not mean that it cannot be done, as long as the physician and the patient discuss the use. However, it would be difficult for the insurance companies to approve and pay for “off labeled” procedures.
In the United States we have the FDA and any device that is implanted has to undergo very stringent testing. The testing and the requirements outside of the United States are not as stringent. In many ways this frustrates both the patients and the physicians, but it is for the patient’s protection. There are many patients that go abroad for disc replacement.
This is certainly an option and many patients in the past have done this. However, one must be aware of the fact that if he or she have a complication that it will be difficult to find a surgeon they can follow-up with unless it was arranged before going outside the United States. This is because the surgeon that implanted it is responsible for the patient’s care at least for the first 3 months.
Part of the reason is the manufacturers charge more for the devices in the US, in fact, almost 3 to 4 times more. However, at the Texas Back Institute through special arrangements with the hospital for those patients whose insurance will not cover the disc replacement, we actually can perform the surgery for the same cost as in Europe with the added advantage that you will have a surgeon that is available to you 24/7.