Multifidus Muscle Pain: Causes, Symptoms, and Relief

Pain linked to the multifidus muscle is one of the most under-recognized contributors to chronic low back pain. The multifidus is a deep spinal muscle that accounts for more than two-thirds of the stiffness that keeps your lumbar spine stable, and when it stops working properly, the result is often a self-reinforcing cycle of weakness, fat infiltration, and recurring pain that doesn’t resolve on its own. Understanding how this muscle fails and what actually helps is more nuanced than a simple “stretch it out” approach, and the research in this area has advanced considerably in recent years.

What the Multifidus Actually Does

The lumbar multifidus sits close to the spine, spanning one to three vertebral segments at a time. Unlike the larger, more superficial back muscles you can feel when you twist or bend, the multifidus works more like a series of tiny guy-wires: it provides segmental stability, resists shear forces between individual vertebrae, and handles compressive loads. A scoping review in Pain Medicine describes it as the strongest spine stabilizer, noting that it also contains a dense concentration of muscle spindles that feed proprioceptive information back to the nervous system. In practical terms, this means the multifidus doesn’t just hold your spine in place; it constantly senses where your spine is in space and fine-tunes its position during every movement you make.¹

That dual role, both structural support and sensory feedback, is what makes multifidus problems so disruptive. When a large surface muscle like the quadriceps weakens, you notice it as reduced strength. When the multifidus weakens, you lose both strength and the fine motor control that keeps each vertebral segment from shifting under load. The spine becomes less stable at a level you can’t consciously compensate for.

How the Muscle Breaks Down

Multifidus dysfunction typically begins with what researchers call reflex inhibition. After an initial injury or painful episode, the nervous system reflexively dials down the muscle’s activation, almost like a circuit breaker tripping.² The problem is that this inhibition doesn’t switch off when the pain settles. Research has shown that multifidus wasting persists even after an acute episode resolves, and this lack of localized muscle support is thought to be a key reason why low back pain recurs so frequently after a first episode.³

Once the muscle starts to atrophy, fat begins to replace functional tissue. A systematic review and meta-analysis in The Spine Journal pooled data from multiple studies and found that people with low back pain had smaller multifidus cross-sectional area than pain-free individuals, and a medium-sized increase in fat infiltration within the muscle.⁴ This fatty replacement isn’t just cosmetic on an MRI; it represents actual loss of contractile tissue. And it tends to get worse with age, as both muscle size and functional tissue decrease over time while fat content climbs.⁵

Microscopic examination of multifidus tissue from people undergoing surgery for disc herniation paints an even more detailed picture. Researchers have found significant numbers of pathological muscle fibers, including moth-eaten fibers and grouped atrophy, especially on the side of the herniation. These changes were statistically worse in the affected segment compared to the unaffected side, suggesting that localized nerve or disc problems drive very targeted muscle damage.⁶ In separate tissue analyses of multifidus samples from disc herniation patients, fat infiltration and fibrosis each accounted for roughly 14 to 15 percent of the muscle, and the muscle contained high concentrations of stem cell populations whose gene expression profiles differed from healthy muscle, which may partly explain why the multifidus is so prone to degenerative changes.⁷

Recognizing Multifidus-Related Pain

There is no single symptom that screams “multifidus problem.” Instead, the pattern tends to look like this: deep, aching low back pain that worsens with sustained positions or repetitive loading, a sense that the spine feels unstable or “gives way” during certain movements, and difficulty controlling the lower back during tasks like bending, lifting, or transitioning from sitting to standing. The pain often localizes to one side and may be most noticeable at the L4-L5 or L5-S1 levels, which is where the multifidus is thickest and does the most work.

Because the multifidus also feeds proprioceptive information to the brain, its dysfunction can show up as balance problems. In people with lumbar spinal stenosis, those with poor balance had measurably thinner multifidus muscles and smaller cross-sectional area at the L4-L5 level than those with normal balance. Increased multifidus size at that level was associated with reduced odds of balance impairment, and there was a significant correlation between static balance measures and both muscle thickness and area.⁸ Separately, exercise therapy research has confirmed that changes in multifidus thickness correlate with improved postural stability and decreased pain intensity, and that declining thickness in otherwise healthy people may be an early warning sign of developing chronic low back pain.⁹

How It Gets Diagnosed

Most clinicians will suspect multifidus dysfunction based on history and physical exam. A prone instability test, where you lie face down on a table with your legs off the edge and the clinician presses on the painful spinal segment, is commonly used. If the pain reproduces when your legs are off the ground (muscles relaxed) but eases when you lift your legs (engaging the stabilizers), that suggests segmental instability consistent with multifidus weakness.

For a more objective picture, ultrasound imaging has become a practical clinical tool. Rehabilitative ultrasound imaging can measure how much the multifidus thickens when you try to contract it, and research has shown this measurement is strongly correlated with the muscle’s actual electrical activity during low-level contractions.¹⁰ One study comparing people with and without chronic low back pain found that the pain group had significantly smaller multifidus cross-sectional area and a significantly reduced ability to voluntarily contract the muscle, both measured at the L5 level.¹¹

MRI provides even more detail, especially for measuring fat infiltration, but it’s expensive and not always necessary for guiding treatment. Newer techniques combine ultrasound measures of stiffness and contraction with MRI-based fat assessment to build a more complete picture of both the muscle’s structure and its mechanical function.¹²

Exercise and Rehabilitation

Targeted exercise is the first-line treatment, but the evidence here has a frustrating wrinkle. Motor control exercises, which specifically train the deep stabilizers including the multifidus, can be effective for individual patients. However, the population-level results have been underwhelming, largely because most people with chronic low back pain struggle to voluntarily contract the multifidus in the first place. Some researchers believe this difficulty stems from arthrogenic muscle inhibition, the same reflex shutdown that caused the problem, which persists even when a patient is actively trying to engage the muscle.¹³

That doesn’t mean exercise is useless. It means the type of exercise matters, and expectations should be realistic. Approaches that combine motor control training (learning to isolate and activate the deep stabilizers) with progressive strengthening exercises for the broader extensor muscles appear promising. Clinical trials are comparing these combined protocols against general exercise programs to determine whether targeting the multifidus specifically adds value over just getting stronger overall.¹⁴ In practice, many physiotherapists use ultrasound biofeedback during training sessions so patients can actually see the muscle contracting (or failing to contract), which helps bridge the gap between intention and activation.

Dry Needling for Multifidus Trigger Points

When the multifidus develops painful trigger points, dry needling is a technique that has gained traction. A randomized trial compared two deep dry needling approaches in patients with low back pain: one with needle manipulation (rotating or pistoning the needle within the tissue) and one without. The manipulation group had significantly greater reductions in pressure pain sensitivity both immediately after treatment and at one-week follow-up. However, a single session didn’t measurably improve multifidus muscle function on electromyography, suggesting the technique works more on pain modulation than on restoring the muscle’s contractile ability in the short term.¹⁵

Interestingly, the benefits may be more pronounced in certain patients. A separate study found that people who responded well to dry needling showed larger improvements in both multifidus contraction and pain sensitivity at one week compared to non-responders, though these differences weren’t apparent immediately after the needle was removed.¹⁶ The takeaway is that dry needling can be a useful adjunct for reducing pain enough to participate more effectively in exercise rehabilitation, but it’s not a standalone fix for the underlying muscle dysfunction.

When Surgery Is Part of the Picture

Spine surgery can help the conditions causing multifidus problems (like disc herniation or stenosis), but the surgery itself can damage the muscle if it requires extensive retraction or dissection of the tissue. This is one of the strongest arguments for minimally invasive surgical approaches when they’re appropriate. A study comparing minimally invasive versus conventional open posterior lumbar interbody fusion found striking differences: the conventional open group lost about 37 percent of multifidus cross-sectional area at the operative level, while the minimally invasive group lost about 12 percent. Fat infiltration markers told the same story. These changes in multifidus health correlated with postoperative pain scores and functional disability.¹⁷

Newer surgical techniques are also being developed with multifidus preservation in mind. Cortical bone trajectory screw placement, which takes a different angle through the vertebra than conventional pedicle screws, has been shown to cause less multifidus fat infiltration than traditional approaches while achieving comparable short-term clinical outcomes.¹⁸ Another comparison of conventional versus minimally invasive decompression surgery found that while the conventional group had more multifidus degeneration overall, the difference for the multifidus specifically didn’t reach statistical significance in that particular study, though the effect on the neighboring erector spinae muscle was significant.¹⁹ The trend across the surgical literature, though, is consistent: less tissue disruption during surgery means better multifidus preservation and less postoperative pain.

Neurostimulation and Regenerative Approaches

For people with refractory chronic low back pain where exercise has failed and further surgery isn’t warranted, an implantable device called a restorative neurostimulator has emerged as an option. The device delivers electrical stimulation to the medial branch of the dorsal ramus, which is the nerve that supplies the multifidus. In a randomized sham-controlled trial of 204 participants who had confirmed multifidus dysfunction (based on a positive prone instability test), those receiving therapeutic stimulation twice daily showed improvements over the sham group.²⁰ A meta-analysis of six studies covering 650 patients found pooled mean pain score reductions of about 3.2 points at one year and 4.1 points at four years, with functional disability scores exceeding clinically meaningful improvement thresholds at both time points.²¹ Five-year follow-up data suggests the benefits are durable rather than fading over time.²²

On the regenerative side, platelet-rich plasma (PRP) injections directly into atrophied multifidus tissue have shown early promise. In a study of patients with single-level degenerative disc disease, about 88 percent of those who reported satisfaction showed increased multifidus cross-sectional area and decreased fatty degeneration on MRI at 12 months after PRP injection.²³ The study is small and non-randomized, so the results should be read cautiously, but the concept of directly addressing the muscle’s degenerative changes rather than just managing pain downstream is an appealing direction.

The Fear Factor

One underappreciated driver of ongoing multifidus dysfunction is pain-related fear. People who are afraid that movement will hurt them move differently, and this is measurable. Research has shown that across ten trunk muscles assessed during maximal effort, participants with high pain-related fear generated peak muscle activity that was only about half of what low-fear participants produced.²⁴ If you’re unconsciously bracing against pain and simultaneously inhibiting your trunk muscles to avoid triggering it, you’re effectively reinforcing the very muscle dysfunction that contributes to the problem. This is why effective rehabilitation for multifidus-related back pain often needs to address fear-avoidance beliefs alongside the physical training component.

Multifidus Changes in Adolescent Scoliosis

Multifidus asymmetry isn’t limited to adult back pain. In adolescents with idiopathic scoliosis, imaging studies have found that the multifidus is significantly larger on the convex side of the spinal curve (the outside of the bend) compared to the concave side.²⁵ Earlier MRI work found that the concave-side multifidus at the apex of the curve showed morphologically abnormal signal changes in most patients with severe or rapidly progressive curves, while the convex side remained normal.²⁶ Whether these asymmetries are a cause or consequence of the scoliosis remains debated, but the findings suggest that the multifidus is involved in the condition’s progression and may be relevant to rehabilitation strategies in younger patients.

Why the Muscle Doesn’t Bounce Back on Its Own

Perhaps the most clinically important thing to know about multifidus dysfunction is that it persists after pain resolves. This was demonstrated decades ago: even after a first episode of acute low back pain had fully settled, the multifidus on the affected side did not recover its normal size without specific targeted exercise.³ The dysfunction continues because the pain-driven inhibition that shut the muscle down outlasts the pain itself, likely contributing to the well-known pattern where back pain recurs in the majority of people who have experienced it once.²⁷

This is the detail that changes how you should think about back pain recovery. Feeling better is not the same as being better. If you’ve had a significant episode of low back pain and you stop all rehabilitation once the pain is gone, the multifidus remains atrophied and infiltrated with fat, your segmental stability remains compromised, and you’re set up for the next episode. Targeted reactivation of the multifidus, whether through motor control exercises, biofeedback-guided training, or other methods, is the piece that interrupts the cycle. The research is clear that this step doesn’t happen passively. It requires deliberate, specific effort directed at a muscle most people have never heard of.