New Research Shows Spinal Manipulation May Actively Help Herniated Discs Heal — Not Just Mask the Pain
- Kelson English, DC
- Apr 29
- 4 min read
Back pain from a lumbar disc herniation (LDH) is incredibly common — and notoriously stubborn. Many people hope the herniated disc material will eventually "reabsorb" on its own, and science confirms that spontaneous resorption does happen in many cases through the body's inflammatory response. But what if a common hands-on therapy could actually speed up that natural healing process?
A 2026 study published in the American Journal of Translational Research suggests exactly that. Researchers found that spinal manipulative therapy (SMT) — the type of precise spinal adjustments performed by chiropractors and some physical therapists — not only relieved pain effectively in an animal model of disc herniation but also promoted faster and more complete resorption of the extruded nucleus pulposus (the gel-like material that leaks out in a herniation).
Understanding Lumbar Disc Herniation and Natural Healing
When a disc herniates, the soft inner nucleus pulposus (NP) can push out and irritate nearby nerves, causing significant pain, inflammation, and sometimes numbness or weakness in the legs (sciatica).Interestingly, the body often treats the extruded NP as foreign material. It mounts an inflammatory response involving immune cells (like macrophages), new blood vessel growth (neovascularization), and enzymes that break down the tissue. Over time — weeks to months — this process can lead to partial or complete resorption of the herniated material, relieving pressure on the nerve.The question the researchers asked: Can spinal manipulative therapy influence this resorption process, or does it only provide symptomatic relief?
The Study: A Rat Model of Disc Herniation
Led by Yaqing Min and colleagues, the team used a well-established rat model of lumbar disc herniation. They implanted autologous nucleus pulposus material onto the L5 nerve root to mimic the compression and inflammation seen in human patients.
The rats were divided into groups receiving:
Spinal manipulative therapy (applied every other day using a customized simulation device designed to deliver controlled spinal adjustments)
Epidural betamethasone (a steroid injection, used here as a positive control for pain relief — referred to as SHD in the study)
Sham treatment (control)
The researchers followed the animals for 28 days, measuring mechanical allodynia (heightened pain sensitivity, a proxy for neuropathic pain), tissue changes via histology, inflammatory markers, and molecular signaling pathways.
Key Findings: SMT Outperformed Steroid InjectionsThe results were striking:
Pain relief: SMT significantly reduced mechanical allodynia starting as early as day 3 and continued to provide strong relief throughout the study period. It outperformed the steroid injection group in both speed and sustained effect.
Tissue resorption: By day 28, rats receiving SMT showed near-complete resorption of the implanted nucleus pulposus material, with much better tissue restoration on histological examination compared to the steroid group.
Balanced inflammation: Unlike steroid injections, which broadly suppress inflammation (potentially slowing natural resorption), SMT created a more favorable "Goldilocks" environment. It moderately increased certain pro-resorption factors — such as TNF-α, IL-1β, VEGF (which promotes new blood vessels), and MMP-3 (an enzyme involved in breaking down matrix) — while preventing excessive inflammation and cell death (apoptosis) in the NP tissue.
The therapy appeared to fine-tune the inflammatory response: enough to recruit macrophages and promote remodeling, but not so much that it caused prolonged damage or excessive pain.
The Molecular Mechanism: JNK-Dependent Pathway
One of the most important contributions of this study is the identification of a key signaling pathway. The benefits of SMT were linked to the regulation of mitogen-activated protein kinases (MAPK) and NF-κB pathways, with a central role for JNK (c-Jun N-terminal kinase).
When the researchers repeated the experiment in JNK2-knockout mice, the positive effects of SMT on pain relief, inflammation control, and NP resorption were completely abolished. This strongly suggests that SMT works, at least in part, through a JNK-dependent mechanism that helps balance inflammation and accelerate tissue remodeling.
In simpler terms: The mechanical input from spinal manipulation appears to send signals that tell the body's repair systems to clean up the herniated material more efficiently while protecting nerve tissue and reducing pain.
What This Means for Patients (With Important Caveats)
This preclinical study adds intriguing mechanistic support to what many clinicians observe in practice: spinal manipulation can provide meaningful relief for patients with lumbar disc herniation and radiculopathy.
It suggests SMT may offer advantages over steroid injections alone by actively supporting the body's natural resorption process rather than just suppressing symptoms. Steroids can provide rapid short-term relief but may interfere with long-term healing if they overly dampen the necessary inflammatory cleanup crew.
Important limitations:
This was a rat model, not a human clinical trial. While the model is commonly used and the findings are mechanistically detailed, results need to be confirmed in people.
The SMT was delivered via a customized device calibrated for rats — human chiropractic or osteopathic adjustments differ in technique and force.
Long-term outcomes beyond 28 days were not assessed.
That said, the study aligns with growing clinical evidence supporting manual therapies for radicular pain and provides a plausible biological explanation for why some patients experience not just symptom improvement but actual resolution of the herniation over time.
Bottom Line
Herniated discs don't always require surgery or long-term medication. Many resolve naturally, and this research suggests that spinal manipulative therapy may help tip the scales in favor of faster, more complete healing by modulating inflammation and tissue remodeling through specific molecular pathways like JNK.
If you're dealing with back or leg pain from a suspected disc issue, consult a qualified healthcare provider (chiropractor, physical therapist, or spine specialist) to determine if conservative care, including manual therapy, is appropriate for your situation. Early, appropriate movement and hands-on care may support your body's own remarkable ability to heal.
Reference:
Min Y, et al. Spinal manipulative therapy promotes nucleus pulposus resorption and alleviates pain in a rat model of lumbar disc herniation via JNK-dependent regulation of inflammation and tissue remodeling. Am J Transl Res. 2026 Feb 15;18(2):1249-1263.
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