What Is a Spinal Subluxation and How Is It Treated?

A spinal subluxation means different things depending on who is using the term. In orthopedic medicine, it refers to a partial dislocation of a vertebral joint, visible on imaging and usually caused by trauma or disease. In chiropractic practice, the “chiropractic vertebral subluxation” (CVS) describes a functional misalignment or restricted motion segment believed to affect nerve function and, by extension, broader health. These two definitions share a word but diverge considerably in how they are diagnosed and treated, and that distinction matters for anyone trying to make sense of what a practitioner is actually telling them.

The Orthopedic Definition

When an orthopedic surgeon, emergency physician, or radiologist says “subluxation,” they mean a joint where the bony surfaces have partially lost contact with each other but have not fully dislocated. In the spine, this can happen after a car accident, a fall, or in the context of conditions like rheumatoid arthritis or Down syndrome, where ligament laxity allows vertebrae to shift out of normal alignment. These subluxations show up clearly on X-rays, CT scans, or MRI. They can compress the spinal cord or nerve roots, causing numbness, weakness, or pain, and in severe cases they require surgical stabilization. This is a straightforward structural diagnosis with well-established imaging criteria, and it is not controversial.

The Chiropractic Vertebral Subluxation

The chiropractic concept is more contentious. D.D. Palmer, who founded chiropractic in the 1890s, proposed that vertebrae could shift slightly out of position and press on nerves, leading to too much or too little function in the body. His students expanded on this idea in the early 1900s, developing several variations of the original theory.¹ Over the following decades, the concept evolved from a simple bone-on-nerve model into something more complex, incorporating ideas about stress, biochemistry, and nervous system sensitization. By the 1980s and 1990s, both the International Chiropractic Association and the American Chiropractic Association had produced consensus statements that broadened the definition beyond a purely structural idea.²

Today, many chiropractors use “subluxation” loosely to mean a spinal segment that is not moving properly or is contributing to pain and dysfunction. Some still adhere to the classical idea that these misalignments cause disease throughout the body by interfering with nerve flow. Others treat subluxation as shorthand for a joint restriction that responds to manual therapy, without making broader health claims. The profession itself has not fully settled this debate, and calls for clearer terminology and more research have persisted for decades.

How Subluxations Are Diagnosed

In orthopedic settings, the diagnosis is imaging-based. X-rays or advanced scans reveal the degree of vertebral displacement, and measurements determine whether the shift is clinically significant. In chiropractic settings, the process looks different. Chiropractors typically use a combination of patient history, visual assessment of posture, motion testing, and manual palpation, where the practitioner feels the spine with their hands to detect areas of restricted movement, tenderness, or altered position.

The reliability of manual palpation has been studied extensively, and the results are sobering. A systematic review of the evidence found that the reliability of palpating bony landmarks and joint mobility in the low back is poor, and palpation of soft tissue structures produces inconsistent results across different examiners.³ In other words, two practitioners examining the same patient’s spine often disagree on which segment is problematic. Some research using standardized instruments has shown better agreement between operators for lumbar motion measurements, but that required specific measurement tools rather than hands alone.⁴

Some chiropractors use routine spinal X-rays to identify subluxations. However, a narrative review of the evidence concluded that routine spinal X-rays should not be standard practice in chiropractic care. The evidence supports spinal X-rays for diagnosing trauma and certain inflammatory conditions and for assessing progressive structural deformities like adolescent scoliosis, but for most patients the potential harms of routine imaging outweigh the benefits.⁵ This creates a genuine tension: the foundational concept is hard to pin down reliably with hands, and imaging is not recommended as a routine screening tool.

What Happens During Treatment

Regardless of how they define the problem, most chiropractors treat spinal subluxations with some form of spinal manipulative therapy (SMT). The most common technique is the high-velocity, low-amplitude (HVLA) thrust, a quick, controlled push applied to a specific spinal segment. The forces involved vary considerably between clinicians and between regions of the spine. For the thoracic spine, one study measured a mean force of about 364 newtons at the moment of cavitation.⁶ These thrusts produce movements of vertebral bodies into what researchers call the “para-physiological” zone, meaning slightly beyond the range of voluntary movement, and often trigger reflex responses in muscles distant from the treatment site.⁷

The popping or cracking sound that often accompanies manipulation comes from cavitation within the facet joints. A sudden drop in pressure inside the joint capsule causes dissolved gases, mostly carbon dioxide, to form a bubble in the synovial fluid. This gas bubble makes up roughly 15% of the joint volume, and the entire event happens faster than your stretch reflexes can respond.⁸ Studies on facet joint gapping have found that HVLA thrusts increase the separation between joint surfaces compared to simple side-posture positioning alone.⁹

Instrument-Assisted Techniques

Not all spinal manipulation involves the traditional manual thrust. Instrument-assisted methods use handheld devices like the Activator to deliver a controlled, rapid impulse to a vertebral segment. A systematic review found that the Activator produced comparable clinical benefits to HVLA manipulation for acute and chronic spinal pain, TMJ dysfunction, and trapezius muscle trigger points.¹⁰ A randomized trial in people without symptoms showed that instrument-assisted SMT produced an immediate, widespread increase in pain tolerance and a local decrease in resting muscle tension on the treated side.¹¹

Where the instrument contacts the spine turns out to matter. Exploratory research on lumbar instrument-assisted manipulation found that contacting the spinous process produced greater front-to-back vertebral acceleration at adjacent vertebrae, while contacting the facet joint produced greater up-and-down acceleration. The mechanical response dropped off sharply with distance from the contact point.¹² These findings are early-stage, but they suggest that where and how force is applied shapes the mechanical effect on surrounding vertebrae.

Multimodal Care

In practice, manipulation is rarely the only thing that happens during a treatment course. Many chiropractors and physical therapists combine spinal manipulation or mobilization with soft tissue massage, advice, patient education, and exercise.¹³ This makes it harder to isolate the effect of manipulation alone in research, but it also reflects how the treatment is actually delivered.

Why It Might Work, Neurologically Speaking

The original chiropractic explanation was that manipulation moves a bone off a nerve. The current scientific picture is more nuanced. Research suggests that the benefits of spinal manipulation have less to do with correcting a structural misalignment and more to do with how the thrust changes the signals flowing into the nervous system. Manipulation stimulates stretch receptors in muscles and tendons around the spine, and these signals appear to alter how the central nervous system processes pain.¹⁴ One proposed mechanism is that the rapid stretch clears out low-level mechanical or chemical irritants from the tissues around the spine, reducing the background “noise” that can sensitize pain pathways.

More recent work has identified changes in motor neuron excitability, cortical drive, and neural plasticity following manipulation.¹⁵ An EEG study found that chiropractic care was associated with increased resting-state alpha-band connectivity within the brain’s default mode network, with the change persisting at a four-week follow-up.¹⁶ What this means functionally is still being worked out, but it points to the brain rather than the vertebra as the more relevant site of action. Meanwhile, animal studies on nerve root compression have found that mechanical constriction alone may not be sufficient to produce radiculopathy-like pain behavior; chemical factors appear to play a role, too.¹⁷ The takeaway is that the “bone pinching a nerve” model is overly simplistic, and the real story involves the nervous system’s broader response to mechanical input.

Does the Treatment Actually Help

For low back pain, which is by far the most studied condition, the evidence is mixed but generally favorable for modest benefit. A JAMA systematic review of 26 randomized trials covering about 1,700 patients found that spinal manipulation was associated with statistically significant improvements in both pain and function for acute low back pain. No serious adverse events were reported in any of the included trials.¹⁸ For chronic low back pain, a BMJ meta-analysis of 47 trials and over 9,200 participants found that manipulation performed about as well as other recommended treatments for short-term pain relief and produced a small additional improvement in function.¹⁹

One question that comes up frequently is whether a particular style of manipulation matters. A large network meta-analysis of 161 trials and nearly 12,000 participants found that most types of SMT performed comparably to guideline-recommended interventions for spinal pain, and differences between specific manipulation techniques were small and not clinically meaningful. Interestingly, a general, nonspecific approach had the highest probability of achieving the largest effects, rather than a highly targeted technique aimed at a specific segment.²⁰ That finding is worth pausing on, because it complicates the idea that a precise subluxation diagnosis is necessary for effective treatment. If the technique and specific target do not much matter, the value of pinpointing a particular “misaligned” vertebra becomes harder to justify.

Headaches

Cervicogenic headaches, headaches originating from the neck, have a separate body of research. A meta-analysis found a small but significant short-term reduction in pain intensity and headache frequency favoring spinal manipulation, along with a small improvement in disability.²¹ At intermediate follow-up, the benefit on pain intensity faded, but the reduction in headache frequency persisted. A small randomized trial comparing manipulation to sham treatment and a control group found that headache frequency improved in both the real and sham groups, with adverse events being few, mild, and transient. The researchers themselves acknowledged the need for larger trials to confirm these results.²²

Non-Musculoskeletal Conditions

Some chiropractors claim that correcting subluxations can help conditions far beyond back and neck pain, including asthma, digestive issues, and ear infections. The evidence here is weak. A critical evaluation of chiropractic found that the totality of evidence from systematic reviews fails to demonstrate that spinal manipulation is effective for conditions other than back pain.²³ A UK evidence report that evaluated manual therapy for a wide range of non-musculoskeletal conditions rated most of the evidence as inconclusive.²⁴ One review did find some evidence supporting chiropractic care for cervicogenic vertigo and infantile colic, with promising but unconfirmed results for childhood ear infections and pneumonia in the elderly.²⁵ But “promising” is doing a lot of work in that sentence. If you are seeing a chiropractor for something other than musculoskeletal pain, the evidence supporting that choice is thin.

Safety and Risks

Minor side effects after spinal manipulation are common. Large case series have reported that increased pain, muscle stiffness, and headache occur roughly half to two-thirds of the time.¹⁸ In older adults, a systematic review found that most adverse events were mild to moderate, consisting of changes in pain quality, muscle or joint soreness, stiffness, numbness, weakness, fatigue, headache, or dizziness.²⁶

The serious-risk question that gets the most attention is whether cervical (neck) manipulation can cause arterial dissection and stroke. A systematic review concluded that conclusive evidence is lacking both for a strong association and for no association, leaving the question genuinely unsettled.²⁷ A more recent case-control study using US population data took a different analytical approach and found that people who experienced a vertebral artery dissection were actually less likely to have had cervical manipulation in the prior week than to have had a standard medical office visit, and multiple analysis methods failed to show a consistent increased risk of cervical artery dissection associated with manipulation.²⁸ One interpretation is that people with early symptoms of a developing dissection may seek care from either a chiropractor or a physician, and the dissection would have happened regardless. The risk, if it exists, appears to be extremely low on a per-visit basis, but it has not been ruled out entirely.

Children and Spinal Manipulation

Chiropractic care for children is a particularly charged topic. Many parents bring their children to chiropractors for conditions like colic, ear infections, and general “wellness,” despite the limited evidence supporting these uses. A rapid review of safety in children under 10 found that most adverse events were mild, such as increased crying or soreness. It also identified one case report of a rib fracture in a 21-day-old and another of indirect harm in a 4-month-old. The incidence of mild adverse events ranged widely, from less than 1% to about 22%, and the review concluded that whether SMT increases the risk of adverse events in children is unknown.²⁹

A broader review of chiropractic care in pediatrics noted that studies have investigated both musculoskeletal and non-musculoskeletal conditions in children with a range of findings and often no definite conclusion. Despite this, many pediatric patients continue to visit chiropractors.³⁰ The gap between how commonly children receive this care and how little solid evidence supports it is one of the more uncomfortable realities in the field.

Cost Considerations

One practical argument in favor of chiropractic management is cost. A systematic review found that patients with spine-related musculoskeletal pain who saw a chiropractor as their first provider used fewer downstream healthcare services and had lower overall healthcare costs compared to those who started with medical management.³¹ A review of conservative treatments for low back pain noted that specialized physical therapy yielded substantially greater improvement than conventional therapy combined with anti-inflammatory medications, and positioned spinal manipulation alongside physical therapy as offering more sustainable benefits than drug-based approaches.³² These economic comparisons come with caveats about patient selection and the difficulty of controlling for differences between the kinds of people who choose chiropractic versus medical care first. But the pattern is consistent enough across studies that it is worth considering, especially for someone weighing their options for managing recurrent spinal pain.

The Specificity Problem

The finding from the large network meta-analysis, that a general approach to manipulation works about as well as or better than a highly targeted one, creates a philosophical problem for the subluxation concept. If the specific vertebra being treated does not much matter, the diagnostic step of identifying a subluxation at a precise segment becomes less important. Finite element modeling of the cervical spine has shown that external loads can generate compression on nerve roots even in a neutral posture,³³ which suggests that everyday mechanical loading, not just discrete “misalignments,” can affect nerve function. The clinical picture that emerges is one where spinal manipulation helps pain through broad neurophysiological effects rather than by correcting a specific structural fault.

This does not mean chiropractic treatment for spinal pain is useless. The clinical trial data show real, if modest, benefits for back pain and some neck-related conditions. It means the theoretical scaffolding of the subluxation may not be the best explanation for why the treatment works. Whether that distinction matters to a patient in pain is a separate question from whether it matters to the scientific understanding of the therapy.