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Spondylolisthesis Fusion vs ULBD

In Degenerative Spondylolisthesis, Unilateral Laminotomy for Bilateral Decompression Leads to Less Reoperations at 5 Years When Compared to Posterior Decompression With Instrumented Fusion

Study Purpose

Multicenter retrospective cohort study comparing the results of unilateral laminotomy for bilateral decompression versus posterior decompression with instrumented fusion for low-grade degenerative spondylolisthesis with lumbar spinal stenosis.

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Discussing news and issues in orthopedics and spine healthcare - this is Spine Talk. Hi, I'm Dr. John Shim, and today on spine talk we are gonna be talking about spondylolisthesis surgical options. In specific, we're gonna talk about a study that was published in Spine just recently November 1, 2019. And the study is titled In Degenerative Spondylolisthesis Unilateral Laminotomy for Bilateral Decompression Leads to Less Reoperations at Five Years When Compared to Posterior Decompression With Instrumentated Fusion. That's a long title, but it basically describes the issue. You know traditionally when patients were diagnosed with degenerative spondylolisthesis, and also had symptomatic lumbar spinal stenosis that did not improve over time, the standard surgical option or discussion was about fusion in combination with decompressive surgery. That was relatively the gold standard since the early 1990s. Since that time however, there's been an explosion of development of what we call less invasive or minimally invasive techniques. Traditionally, when doing a decompression we often did a wide pedicle to the pedicle laminectomies with partial facetectomies to make sure we have good decompression of the central canal and the neural foramen. Well, with the advancement of minimally invasive techniques there has been the development of the so called unilateral laminotomy would bilateral decompression. The advantage of this technique is it spares most of the facet joints, it spares the midline dorsal ligamentous complex, it spares the mid portion of the neural arch, and it prevents the muscular and ligamentous attachments to the contralateral side. Effectively, you are not causing a iatrogenic instability by removing all those structures. Because we preserve these stabilizers, more surgeons have been before terming this surgical technique instead of the traditional midline decompression and fusion. Now, there are naysayers saying that this technique probably shouldn't be utilized still because we're not sure if there's adequate decompression being performed, but of the people who are using the technique many are reporting good results. So, what this study did is compare the population of those who had the option of having this unilateral laminotomy bilateral decompression or the more traditional wide decompression with posterior spinal fusion. This is a retrospective study performed by five Kaiser Permanente north California centers from January 1 2007 until December 31 2011. Exclusion criterias were established, and you can read the paper about it. Basically, chart reviews were done to identify patients who had surgery, and then to find out how many people with the similar diagnosis of a spondylolisthesis with degeneration and spinal fusion had only the unilateral bilateral decompression procedure versus those who had fusions. The numbers were quite different. Of the population that qualified for surgery only 164 of these patients chose the unilateral laminotomy and bilateral decompression. During that same period 3,457 patients with degenerative spondylolisthesis with stenosis underwent diffusion and decompression procedure. So, there was a little bit of a challenge. There was a huge group who had the traditional decompression, and fusion and there's a much smaller group that had the unilateral laminotomy and decompression. So, to try to make a study out of this the authors used something called a "propensity scoring matching system", and what they did was identify at least three fusion patients who matched in many respects such as age, sex, race, smoking status; compared to the patients who had the unilateral laminotomy and decompression. Basically, 437 patients who had decompression and fusion were selected to be the fusion cohort versus the 164 patients who had the unilateral laminotomy and decompression. Again, because of the luxury of this large group of fusion and decompression patients, effort was made to match the fusion group, the fusion cohort, in terms of their body mass index, their age, their sex, their ethnicity, their smoking status, and also their medical comorbidities. So, what was the results? Well, this is not a surprise. Patients who had the unilateral laminotomy and decompression, more of a minimally invasive procedure, had a much decreased mean length of stay in the hospital. They averaged 2.3 days versus the fusion patients who were in the hospital for 4.6 days. Also not a surprise, those who had the minimally invasive laminotomy and bilateral decompression instead of the fusion had much less blood loss than those who had the fusions. What is interesting is the patients who had the unilateral laminotomy and decompression had a lower five-year reoperation rate. It was about 10% versus 17% for the fusion population. What was also, to me kind of interesting is, patients who had the unilateral laminotomy and decompression had a much higher return rate to the emergency room within 90 days. Those with just a laminotomy had a 12% return to the ER within 90 days versus only 5% for patients who had lumbar fusions and decompressions. That was a little bit of a surprise to me. What was also interesting is, after 90 days the so-called 90 day post-op period, there was really no difference in the postopper complication rates, or reoperation rates, for both patient populations. So, long-term, there was some important highlights to the study. Patients who had the unilateral bilateral decompression were more likely to have reoperations at the same level of the decompression. That kind of goes in the line of what a lot of you know more traditional surgeons will say. Well the unilateral decompressions just won't do the job as a more traditional decompression - so you'll have a higher rate of reoperation. What we don't get to weigh in that statement is we also realize that the fusion group were much more likely to have reoperations at another level. In other words, maybe developing more adjacent level disease. Overall, as we stated before, the fusion rate and decompression patients did have a much higher rate of returning back to the operating room over five years versus those who just had the unilateral laminotomy and bilateral decompression. So, you know the studies have some limitations. The outcome is really based on reoperation rates, and not necessarily based on clinical outcomes. Well, you say, well what's the difference? Well, that can be a pretty big difference. Some people can have horrible clinical outcomes, but they just don't want to have anymore surgery. So, they may not have a good outcome, but they may not have had additional surgery. The other issue is, the author limits that the study is retrospective in nature. In other words, we look back to see what happened to these people, and then we also had to select a group of people who had spinal fusions to try to match them demographically to the group that had the bilateral, excuse me, the unilateral laminotomy and decompression. That's not exactly a perfect way of comparing populations, but is the best they can do. The other issue is, when they did the retrospective review it wasn't clear how the surgeons decided who would have the unilateral laminotomy and decompression without fusion versus those who definitely had the traditional decompression and fusion. We don't know if they had other factors like x-rays taken before the operation showing instability. So it led the surgeons to offer the fusion operation versus the decompression laminotomy operation. There's also exclusion of a population of patients who expired before the 5-year follow-up period. We don't know if because we didn't measure the outcomes of these people who died that did that skew or change the outcomes for the results of reoperation rates. Also, as far as the fusion patients are concerned, there is different fusion techniques utilized, and because of that we're not sure if the outcomes of the fusion patients was also different or skewed because of different techniques utilized. There is also another issue that may have significant bearing on what kind of conclusions we can make from this study. There wasn't a good accounting for the presence of pre-existing adjacent level disc degeneration in either population. So we don't know if these people were already predisposed to having significant adjacent level disease, and so they may have had to need surgery anyway over time. This study, you know, I think they're trying to do something that's helpful, but because it's retrospective and the numbers are so skewed I'm not sure how much we can use this information as saying this is actually in refute of the traditional gold standard of doing decompression and fusion for patients with degenerative spondylolisthesis with spinal stenosis. On the other hand, certainly with these current surgical techniques, these more minimally invasive techniques that are becoming more mainstream, perhaps there is a time when you need to explore whether using minimally invasive techniques truly will be more protective, and less likely to cause a development of spinal fusion needs in the future. In the end, a future prospective study that looks at a population that has degenerative spondylolisthesis and lumbar spinal stenosis needs to be randomized, and a certain percentage should have the fusion, a certain percentage should have the decompression, and then you should be able to compare the long-term outcomes. Even within that, because the patients are not blinded, and the surgeons aren't blinded to the what techniques they're using and what results they may anticipate, and because the recoveries are so different between the decompression only patient population versus the decompression and fusion populations, I'm not sure if we can really draw those answers as easily as we'd like. But at any rate, if we have more of a prospective randomized study, maybe we can then address the issues of do we need to do fusions all the time for people who have degenerative spondylolisthesis with stenosis? Can we save cost by using more minimally invasive techniques, and avoid fusion operations, additional operations in the future? Can this technique provide better satisfaction and outcomes for a patient population? We don't know the answers to this. I applaud the authors who we're trying to answer these questions, but at this point I can't say that we can definitely say that this is an end all to all the discussion and debate about this technique. It certainly needs more exploration. I'm John Shim, I hope you enjoyed watching this video. I know it's a little bit esoteric. I think for the surgeons out there it may be more relevant, but if you find these videos helpful please subscribe to our YouTube channel, or if you'd like you can come to our websites which is or Thank you.

Last modified: January 16, 2020

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