Deciding on artificial disc replacement surgery
Spine-health.com expert featured on Back Pain Radio
Not all patients are ideal or eligible candidates for artificial disc replacement. The decision to have artificial disc surgery is based on a combination of the patient’s history, response to conservative treatments and results from diagnostic tests, such as an MRI scan, x-ray and discogram. Read what Justin Tortolani, M.D., an orthopedic spine surgeon in Maryland and a member of Spine-health.com, and Grant Cooper, M.D., host of Back Pain Radio, had to say about the decision process for when to have artificial disc replacement surgery on the April 18, 2005 show.
Transcript of Back Pain Radio show on the decision process for artificial disc replacement surgery
Below is the transcript summary from the Back Pain Radio show, What is artificial disc replacement and how do you know if it’s right for you?, from April 18, 2005.
Dr. Cooper: What is lumbar artificial disc replacement?
Dr. Tortolani: It’s really a way to reconstruct one specific motion segment of the spine by removing a painful disc and inserting a prosthetic device that affords natural motion.
Dr. Cooper: So, this is for people who you suspect the disc is the cause of pain?
Dr. Tortolani: That’s right. In our field we call it discogenic back pain or pain stemming from the disc itself.
Dr. Cooper: Who is a candidate for lumbar artificial disc replacement?
Dr. Tortolani: Well, we recently completed an FDA trial, which was a prospective, randomized trial, which included patients throughout the United States that had one single level in their spine that could be identified as causing pain and one specific disc as the pain generator. Patients had to meet pretty strict criteria to gain access to the study. They couldn’t have anything like osteoporosis, for example, which might weaken the bone that would support the implant. They couldn’t have other types of metabolic bone disease or cancer or other tumors of the spine and they couldn’t be on chronic steroids.
Dr. Cooper: Why couldn’t they be on chronic steroids?
Dr. Tortolani: The steroids could actually weaken the bone and cause osteoporosis. We wanted to have patients who were as healthy as possible and would have as clearly defined problems as possible so that we could address it effectively with the artificial disc replacement.
Dr. Cooper: So these are people who didn’t have those other co-morbidities, those other problems, and you’re suspecting single level disease, but how did they come to you? Did they come in to their doctor with back pain, and what makes them a candidate? How did the doctor begin with the process of identifying that person as somebody who might benefit from a disc replacement?
Dr. Tortolani: Well, the key really is the history. There are different patterns of back pain, as you know. With degenerative disc, most people have what we call activity-related pain. They have pain doing certain activities, especially bending or stooping or squatting. People will notice that they have to limit activities like they like to do around the house, especially gardening. Other people will notice even household chores, like vacuuming or bending down to lift things up off the floor, will cause them to have low back pain. That’s how they initially present. These patients tend to have very good relief of their pain when they rest, so if they sit down or lie down and take on a recumbent position, their back pain goes away. We like to see that sort of pattern of pain in their history. And it’s probably their history that’s the most important in our evaluation.
Dr. Cooper: Say a person comes in and they give that kind of a history, where they have pain with movement, worse with bending over, it’s better when they lie down. Is this the first thing that gets offered to them, or how does the workup continue?
Dr. Tortolani: That’s a great point. We really try to manage all of our patients without surgery. In other words, we try to offer non-operative types of treatments initially. Once we identify the disc as the problem, we try to do things that will minimize pain from that disc, probably the most important of which is strengthening the stomach and the low back muscles that support the spine. Just like someone that has a “bad knee” or a degenerative knee, we try to strengthen the muscles, like the quadriceps muscles, around the knee to reduce the stress the knee joint itself experiences. So, it’s an analogous situation in the spine. There are other things we like to do, like taking non-steroidal anti-inflammatory medications like Advil or Aleve, that can help minimize the pain from a degenerative disc. Even Tylenol is something that we often will recommend. And then there are increased levels of invasiveness of treatment. The last level of invasiveness, obviously, would be surgery.
Dr. Cooper: Can you mention the sort of step-by-step approach that you might go through before getting to disc replacement? Say there’s a patient who has low back pain, and they’re wondering if they’re a candidate for this type of surgery. What sorts of things might their doctor try before attempting the surgery? You mentioned strengthening the surrounding muscles, so physical therapy, some over-the-counter medications. What else might they try?
Dr. Tortolani: Yes. I like to think of the treatment really in three phases. The first stage is what we call lumbar spinal stabilization, which are exercises aimed at strengthening those core muscles that I mentioned – the stomach and the low back. That can be not only dry land activities but also aquatic treatments. Getting into a pool, not even necessarily to swim laps, but just to get into a pool provides a buoyant environment so that the weight of gravity across the spine is reduced dramatically. People can, therefore, strengthen muscles in a non-painful way. Then, that type of treatment, that stabilization treatment, in addition to the over-the-counter medications, is what I group into my level 1 or group 1 type of treatments.
Following that, let’s say someone pursues that for 2 to 3 months, and their back pain persists - either it’s no better, it’s worse, or they’re just not satisfied with their progression. Then I’d look at level 2 types of treatments, and that’s the next level of invasiveness. One type of treatment may be a cortisone injection or a steroid injection into the spine. An epidural type of injection delivers a steroid medicine right around the nerves that go to the disc that may be painful. There’s also something called facet joint blocks. These facet joints are small joints in the spine that can also be painful, and if we can get an anti-inflammatory delivered right to the painful area, sometimes we can reduce the pain that way. Obviously, that’s an injection, and it can be painful and we don’t typically give them anesthesia or put them to sleep to do it. So, it is an extra level of invasiveness, and that’s why I call it my level 2 treatment.
I will typically manage patients with low back pain of this sort for a minimum of 6 months before I’ll even consider fusion or other surgery, like disc replacement, for their pain.
Dr. Cooper: Okay. So, now say we have the patient who’s have been through the two levels, it’s been about six months, and you have the conversation about potentially having a disc replacement. First, how do you know which disc to replace?
Dr. Tortolani: Once the patient has exhausted the traditional non-operative measures and we’re starting to think about surgery as a potential treatment plan, we sure want to hone in on the disc that’s the problem, and the way to do that initially, in addition to their history, is to do a detailed physical examination. We want to make sure that there is no neurological problem or weakness in the legs, or spinal cord impingement, or nerve root impingement. But once we’ve satisfied that, the next best test would be a plain old x-ray of the low back. Sometimes we can clearly see on an x-ray that one specific disc is quite degenerative, meaning the disc has lost its normal height, it’s lost its “shock absorbing ability.” We see that on an x-ray by several different things. One is we see the disc is worn out; it’s not as tall as the other discs. Also, you can have bone spurs that form around the disc to try to stabilize that spinal segment. Finally, the bone itself has a very specific shape in the low back, and the bone starts to change shape as the disc degenerates. So, there are specific things we look at on the x-rays to help confirm our suspicions based on the history and the physical exam.
Dr. Cooper: When you look on the x-ray and you see one level that looks like it’s degenerated, do you then go right to disc replacement or are there other steps to confirm that diagnosis?
Dr. Tortolani: The next step would be to get what’s called an MRI scan or a magnetic resonance imaging scan. That is not an invasive test, but it does require the patient to sit in a tube, lying flat in a tube for approximately 40 minutes or so. That sort of test gives us excellent anatomic detail into the lumbar spine. We can see the bone much more clearly than we can on x-ray, and we can see the discs very, very clearly. Some of the things that we can see on MRI that we can’t see on a regular old x-ray is actually the consistency, or the specific tissue component, to the disc. What I mean by that is a normal, healthy disc will have high water content, and on an MRI that looks like a bright signal, whereas a degenerated disc has lost its water content and lost its shock absorbing ability and will look very dark on an MRI scan. We call those discs “dark discs,” and, of course, we want the dark discs on the MRI to be the same discs that look abnormal on the x-ray so that we can correlate the two.
Dr. Cooper: If a person is claustrophobic, and they’re worried about lying down in the tube in the MRI, what sorts of options are there for them?
Dr. Tortolani: Well, there are a couple of options. One option, which is emerging, is the open MRI scanners. These scanners have an opening, almost like a sunroof, that patients can see out from. With better resolution and finer magnets now, we are getting good detail on the MRI, even with these open MRI scans. This is not a trivial point, because traditionally, the open MRIs did not have a strong magnet and they didn’t give us as detailed or as high-resolution picture as we needed. It’s not that important for peripheral joints, like a shoulder or an elbow or a knee, because those joints are so close to the skin surface that they can be adequately visualized by a standard open MRI. Whereas the spine is a much deeper structure, and to penetrate that deeply into the tissue, you do need a stronger magnet, which is how the images are generated by MRI. So, the open MRI is an emerging technology which likely will be able to provide very high-quality images for patients that are claustrophobic. Having said that, there is one more imaging modality, which is called a CT scan or a CT scan with myelography. Basically, that is contrast that’s injected into the spinal canal, and that affords us good information about the discs but not nearly as detailed as an MRI scan will.
Dr. Cooper: Okay. Now suppose that we have evidence on the x-ray that correlates with the evidence on the MRI for a certain disc being the cause, being degenerated. Do we then go to disc replacement or are there other steps in the diagnosis?
Dr. Tortolani: The one final step is called discography, and the reason why discography is a potentially important step is because it helps us in one more way to confirm that the disc that we’re interested in truly is the disc or the pain generator for this particular patient. What discography does, it really enables us to provoke, if you will, the disc of interest. A very fine needle is inserted into the disc that appears abnormal on the x-ray and MRI scan, and saline is then injected into that disc. If that disc, after injection of saline, reproduces the patient’s pain, we call that a concordant pain pattern. At the same time, we try to inject adjacent discs to make sure that those discs do not also reproduce the patient’s pain. So you can imagine that if every single disc that gets injected reproduces the patient’s pain, we are left in a situation there where we cannot conclude with accuracy which particular disc is the pain generator. Disc replacement in that scenario would be much more challenging. However, if adjacent discs are not painful and there’s only one disc that is painful, and this is the same disc that on an MRI and an x-ray looks abnormal, why then, we have one more piece of evidence that’s now stacking up in favor that this one particular disc is the cause and the root of the patient’s pain. In that scenario, once we have the burden of proof stacked against this disc, we feel more confident in pursuing disc replacement surgery.
Dr. Cooper: Do you feel like you need all three to be concordant – all those three tests, the x-ray, the MRI and the discogram – before doing the disc replacement, or would you be comfortable with one of the three or two of the three?
Dr. Tortolani: Well, it is important to recognize that discography is not really the be all and end all. It is somewhat controversial, but to answer your question, my feeling is that if the patient has a classic history of discogenic back pain, and they fit the pattern of pain, then if their x-rays and their MRIs point to single-level problems, then I do not think the discography is necessary. But, I do think it’s important to have MRI scans and x-rays that correlate with one another. The issue really comes up more commonly in patients that have a history that’s suggestive of discogenic back pain, an x-ray that shows discogenic problems, but then they have an MRI that shows two or sometimes three dark discs. Then, you’re left questioning, well, which disc is the culprit, and in that particular scenario, I think the discography does have a strong role in helping to clarify the issue.
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