In this episode of The Evidence-Based Chiropractor, Dr. Jeff Langmaid reviews a newly published animal study that investigates how spinal manipulative therapy (SMT) influences the healing of lumbar disc herniations. The study, published in the American Journal of Translational Research (2026), used a rat model where disc material was implanted near the L5 nerve root to simulate herniation. Rats were divided into four groups: control, herniation only, steroid injection, and SMT administered every other day for four weeks. The podcast details the study’s methodology, including pain sensitivity testing, disc tissue analysis, inflammatory marker measurement, and the use of genetically modified mice lacking the JNK signaling pathway. Key findings include: (1) both steroids and SMT reduce pain, but steroids provide rapid, short‑term relief while SMT yields slower but sustained pain reduction; (2) SMT promotes near‑normal disc tissue architecture and greater nucleus pulposus resorption compared with steroids, which suppress inflammatory mediators essential for healing; (3) SMT creates a balanced inflammatory microenvironment, modulating cytokines such as TNF‑α, IL‑1β, VEGF, and MMP‑3; (4) the therapeutic effects of SMT are dependent on JNK signaling—knocking out JNK abolishes pain relief, cytokine balance, and disc resorption. Dr. Langmaid interprets these results as evidence that chiropractic adjustments may facilitate natural disc healing through neurophysiological mechanisms rather than merely providing mechanical pain relief. He emphasizes the importance of educating patients about the beneficial role of acute inflammation, the drawbacks of steroid injections, and the need for appropriate treatment duration and follow‑up care. The episode concludes with practice‑growth recommendations and sponsor acknowledgments.
Welcome to The Evidence-Based Chiropractor, where each week we deliver the latest chiropractic research and marketing strategies, all in the time it takes to get to your office. Now here's your host, Dr. Jeff Langmaid.
Hello and welcome to The Evidence-Based Chiropractor. I am your host, Dr. Jeff Langmaid. This week we are back with more research and this is an awesome study. It's one of the most interesting, creative out there and yet hopefully really applicable studies that I've seen in a long time. And why do I say that? I say that because this study is about how spinal adjustments may actually help herniated discs heal. I'm talking directly from like a neurophysiological perspective. We're going to dive into the study, break out highlights, talking points, and where research like this might go in the future. All that and more on today's episode. Before we get started, big shout out to two of our partners, Shockwave Centers of America, $500 off and a free cart. If you're looking to bring shockwave into your practice, Their units are awesome. They have a really wide selection of just about anything you want, and they're gonna hook you up with $500 off and a free cart by being a listener of this podcast. I'll drop that link down in the show notes. And Leander Tables, $1,000 off their Series 950 using the code EBC2026 or visiting the page in the show notes, having a conversation, letting them know you're a listener. $1,500 in savings right there by being a listener of this podcast. Thank you so much for tuning in, whether this is your first time or whether you've been tuning in for over 530 episodes. Thank you so much. On today's episode, we're talking research. As I said at the top, this is a brand new piece of research that looks at something I think all of us as chiropractors have been hoping, saying, looking at, seeing clinically for decades, and that's that the adjustments that we deliver don't just reduce pain on their own, but it actually may help the body resolve a disc herniation. Now, there's the mechanical aspects of that that I think are really well-proven when we look at traction, spinal decompression, and some adjustments as well. However, we're going to look at it from what I'll call a neurophysiological perspective on today's episode, which is really unique, really compelling. And what makes this study really interesting is it doesn't say just that adjustments help, It tries to answer the questions of how, and specifically how spinal adjustments may help herniated discs reabsorb, how it affects inflammation, and how it compares to one of the most common medical treatments for disc pain, which are, drum roll, steroid injections, my least favorite modality out there. So the title of this study, again, I'm going to drop the link to the study down in the show notes, but the title is spinal manipulative therapy promotes nucleus pulposus reabsorption and alleviates pain in a rat model of lumbar disc herniation via JNK-dependent regulation of inflammation and tissue remodeling. Man, that is a mouthful. Now, you probably heard a couple keywords there. One, spinal adjustment, spinal manipulative therapy. Two, reabsorption of nucleus pulposus. And pain reduction and rat model. So this is not a human model yet, which is why this is emerging research, but it is really, really, really promising. So what's even more interesting is that the researchers identified a specific molecular signaling pathway. That's that JNK pathway that appears to play a really central role in this entire process. So today, again, we're going to talk about this study, talk about what it means clinically, and I'm gonna say most importantly, how you can communicate these findings to your patients in a true and ethical manner. So when patients show up and understand why chiropractic works, they can become a lot more confident in your plan of care. So communication is everything to the success of really any business, any relationship, and certainly to the success that your patients have with the care that you deliver. They can receive some results with poor communication, but man, can they receive best results when there's fantastic communication. So this study was published in the American Journal of Translational Research, 2026, hot off the press. And let's zoom out for a second before we dive into the details and talk about what I'll say is the big idea behind this study. So one of the most fascinating things about disc herniations is that many of them, most of them shrink or resolve naturally over time. You know this, you've seen it in your practice. And imaging studies have shown that the body can actually break down and absorb the herniated disc material. So that process is nucleus pulposus resorption. And here's the key point. That resorption process is actually driven by inflammation, not bad inflammation, but controlled biological inflammation that allows the body to do a few really important things. One, recruit immune cells. Two, break down disc material. Three, grow new blood vessels to bring in those nutrients. And then four, remodel tissue. So you've heard me talk about this many times on this podcast, but acute inflammation is the start of the healing process. It's really good. It's when acute becomes chronic that all of the challenges that we know start. So The acute inflammation process is literally the beginning of the healing process. So really, really important to understand that and know that. And 99%, I'm probably being very conservative, 99.9% of people have no clue that that's the case. They think inflammation, they think bad, they think hurt. That means this is a problem. Well, clearly, if something's hurting, there probably was an injury that caused that. But the inflammatory process, that pain, that true inflammation, redness, all of pallor, all of those items, that's the beginning of the healing process. So it's really, you don't want to diminish that. Often in our, say, our culture, what we try to do as soon as there's inflammation, many people are like, "Oh, I need to get anti-inflammatories immediately." Well, that may or may not be the best thing. That's not where we're going to go today, specifically relative to this study. But it's important to note and just acknowledge with yourself for a moment, most people, most of the time have no clue that inflammation is a part of the healing process. That is a massive gap of knowledge that has to be bridged in order to best communicate with your patients. So where things start to get interesting is that many conventional treatments for disc herniation try to suppress inflammation, right? Steroid injections being one of them. And steroid injections, you know, often can reduce pain quickly, but they also have been shown to directly and indirectly interfere with the exact process that helps the body clear the disc herniation. Why do you think the steroid injections are the road to surgery? Well, I'll sort of, again, I'll leave that conversation for another day, but there's a direct line between receiving steroid injections, especially people who are receiving many of them, in going towards a surgical intervention or an advanced intervention later on. I don't think that's on accident. I'm not saying it's a conspiracy, but what I am saying is people don't know any better. So unless you're getting out there and telling your story, telling the truth, telling the real story of how their body works, how it heals, why you need to give it time, why acute inflammation is good, people end up on a fast track to surgical intervention. We know this because there's like a million elective spine, elective by the way, a million plus elective spine surgeries done each and every year. And I'm convinced an overwhelming majority of those do not need to happen and actually cause then consequences later on that are far beyond even the initial injury. So injections, again, reduce pain quickly. Sometimes that's the case. But it also can proliferate the issue and accelerate the issue towards advanced intervention and further injury. So the researchers really in this case wanted to explore a slightly different question, which was, well, could a spinal adjustment help reduce pain while still allowing the body's natural healing process to occur? And if so, what are the biological mechanisms that are involved? So to investigate this, the researchers created, they actually created a lumbar disc herniation model in rats. And here's how it worked. They implanted disc material near the L5, L5 nerve root to mimic a disc herniation and radiculopathy. Then they divided these animals into 4 separate groups. Number 1, control group, no herniation. 2, model group, herniation only. 3, steroid group, obviously received steroids with the herniation. And then 4, the adjustment group. So herniation plus spinal manipulative therapy. So the manipulation was delivered every other day for 4 weeks using a device designed to mimic a chiropractic thrust. Every other day for 4 weeks. Really critical. Again, don't throw, you know, the pendulum doesn't need to swing all the way one to the other. So this doesn't mean that every patient that has disc herniation needs to be treated every other day for 4 weeks. But what it also means is don't, and I just, I can't emphasize this enough, there are many chiropractors that are in the evidence-based world that get patients out of their practice too quickly. Why? Because They're taking— pain can be reduced very quickly with what we do, but it doesn't mean the healing process is complete. It doesn't mean that any habits have changed. It doesn't mean that they've gone beyond and into the area where they're actually reducing risk for reinjury. So while pain reduction can happen very quickly, it's really important to ensure that your patients are fully taken care of before they are discharged, whether that is one week in, whether that is 4 weeks in or whether they're moving to maintenance care over time and they're coming in systematically over time, whatever is right for that patient based upon their health goals and your findings is really where you wanna live. So over those 28 days, the researchers measured a few things, pain sensitivity, disc tissue changes, inflammatory markers, and molecular signaling pathways. They also conducted experiments using genetically modified mice lacking that key signaling pathway to see whether that pathway was required for the effects of the adjustment. So it wasn't just clinical observations, it was really a mechanistic investigation. So what they found was a few really, really important things. Number 1, the herniation model worked exactly as expected. So animals with disc herniation developed significant nerve-related pain with pain thresholds dropping by about 50% after intervention. So important there. Second finding, both steroid injections and spinal adjustments reduced pain. No surprise there, but the timeline was different. Steroids worked quickly. You put the steroid, you put the drug right there, but it was temporarily. It reduced pain early within the first week or two, but by day 28, the pain had largely returned. Very similar story to what happens in human models. Spinal manipulation showed a different pattern. Pain relief started around day 3 and it continued improving, continued improving throughout the study, ultimately producing better results than steroids by day 28. So steroids worked faster, but spinal adjustments worked longer and better. The third major finding: spinal adjustments also affected disc healing itself. When the researchers examined the disc tissue after 28 days, the untreated group showed, uh, pretty significant degenerative changes and inflammation. Steroid group, partial improvement. Spinal manipulation, spinal adjustment group, near-normal tissue structure and significantly greater resorption of disc herniated material. So the disc material was cleared out, so to speak, more effectively. So there's a lot of different technical reasons and pathways, uh, why this occurred. The researchers measured several molecules including— involved in disc healing, including TNF-alpha, interleukin-1 beta, VEGF, MMP-3. These molecules all played key roles in recruiting macrophages, promoting blood vessel growth, breaking down disc tissue, and remodeling that extracellular matrix, all really necessary for disc resorption. Now, here's what they discovered. The steroids suppressed all of those molecules, which is kind of what's— this isn't like a rag on steroids. That's actually what they're designed to do. I mean, so But that's a problem. And that's the problem. But spinal adjustments produce something really different. Instead of eliminating inflammation, it created moderate levels of cytokines, not too high, not too low, just enough to actually support the healing process. So they describe this, I love this term, balanced inflammatory microenvironment, a balanced inflammatory microenvironment. And that's a really important concept because inflammation is not just good or bad. The body needs the right amount to get the best result. Too much inflammation, pain, tissue damage. Too little, not enough healing. So spinal adjustments appeared to actually kind of regulate this balance. And now we can get to the signaling pathway JNK. Now, JNK is a part of the MAPK family of pathways that regulate inflammation and cellular stress responses. The researchers found that spinal adjustments influence several pathways, including P38, ERK, and JNK. JNK, but JNK appeared to be the master regulator. So when the researchers used genetically modified mice that lacked JNK, the benefits of a spinal adjustment totally disappeared. Pretty wild. No pain reduction, no cytokine balance, no disc resorption, nothing. So it suggests that spinal adjustments actually exert effects through the JNK-dependent signaling. That's a massive insight because it shows that what you do is not just mechanical. It's actually biological, neurophysiological responses, I would say. So what does all this mean for your practice? Well, first it means a couple things. Spinal adjustments may support natural disc resorption. They probably do. It seems like they do. This was in an animal or rat model, but disc herniations don't just sit there forever. The body actively tries to break them down and spinal adjustments might be able to really help facilitate that process. Second big finding, a big key thing, pain relief from adjustments may come from modulating inflammation, not just altering joint mechanics. Important. So that aligns with what we see clinically. Patients improve gradually over time, not just immediately. And third, while steroids can sometimes prevent— excuse me, provide short-term relief, they also suppress the biological processes that are needed for disc healing. So this study showed that steroid-treated animals experienced early pain relief, but worse long-term outcomes compared to adjustments, worse long-term outcomes compared to adjustments. So this is a really fascinating study. I am super, super excited to see where this goes in the future. This was of course an animal study, so more clinical research is needed, but this provides extremely valuable insight into the biological mechanisms behind spinal adjustments, how this works. And really, I'm gonna say, you should be super excited This highlights the power of what you do each and every day in your practice. And I love studies that continue to expand our knowledge base, continue to help us understand the true breadth and depth of what we provide as chiropractors. So this was a great one. I loved it. I can't wait to see where it goes next. And as we wrap up today's episode, big shout out to NovoPulse and their OA Recovery Program. If you have patients with osteoarthritis, and you don't have a specific osteoarthritis recovery program, Novopulse is your answer. They have a turnkey system with everything you need. It's awesome. Check it out down below. They have, I mean, this is founded by gentlemen that have literally hundreds of healthcare and medical patents. So the Novopulse not only has the device, it has the program. So click the link down below, connect with their team, as well as the Diabetes Reversal Group. You have people with type 2 diabetes walking into your practice each and every day. And if you don't have a system and a process for them that's specific, you're just missing opportunity to help more people. And as a byproduct of that, create more revenue in your practice. So click down below, watch the video, and learn about what they do and how they can help impact not only your practice, but most importantly, the people in your community. So if you have not left a rating or review for this podcast, I would deeply appreciate it if you would scroll on down and do so. That helps more and more docs find out about it. And again, whether this is your first episode or 500 plus, Thank you so much for taking time out of your day to tune in. Thank you so much for being a chiropractor. Have a fantastic week in practice, and I will talk to you soon.
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