Can Scoliosis Cause SI Joint Pain?

Scoliosis can contribute to sacroiliac (SI) joint pain, primarily by shifting loads unevenly across the pelvis. Research on degenerative lumbar scoliosis shows that the SI joint on the outer (convex) side of the curve degenerates more than the one on the inner side, and the degree of that asymmetry tracks with the severity of the spinal curve itself. The relationship is more nuanced than a simple cause-and-effect chain, though, because body weight, muscle imbalances, pelvic alignment, and prior surgery all play into whether a person with scoliosis actually develops SI joint symptoms.

How a Curved Spine Loads the SI Joint Unevenly

The SI joints sit where the base of the spine meets the pelvis, and they rely on balanced forces from above and below to stay healthy. When the lumbar spine curves to one side, the weight it transmits downward no longer distributes evenly between the left and right SI joints. A 2026 study in the European Spine Journal examined patients with degenerative lumbar scoliosis and found that SI joint degeneration was significantly worse on the convex side of the curve. The degree of asymmetry between the two joints correlated with the size of the spinal curve (measured by Cobb angle) and with the angle at which the lowest lumbar vertebra tilts relative to the sacrum.

That same study found SI joint degeneration was linked to higher back pain scores and lower quality-of-life measures before surgery, suggesting the joint wear is not just a finding on imaging but something patients feel in daily life.¹ The mechanism is straightforward in concept: a tilted base (the sacrum) forces one SI joint to bear more compressive load and shear stress than the other, accelerating cartilage breakdown on that side over time.

Leg Length Discrepancy Adds Another Layer

Scoliosis and leg length differences often coexist. Sometimes the curve develops partly because one leg is shorter; other times the curve itself creates a functional difference by tilting the pelvis. Either way, the SI joints pay a price. A finite element modeling study found that as leg length discrepancy increased from one to three centimeters, peak stresses and contact loads across the SI joint rose progressively. The authors noted that correcting the discrepancy, whether through shoe lifts or surgical means, should in theory reduce those loads and decrease SI joint pain.²

If you have scoliosis and one leg that measures even slightly shorter, the combination may stress your SI joints more than either condition would alone. This is worth bringing up with a clinician, because a simple heel lift can sometimes take enough pressure off the joint to ease symptoms without any invasive treatment.

How Common Is SI Joint Pain in People With Spinal Deformity?

Estimates vary depending on how strictly SI joint pain is defined. Many patients with spinal deformity report pain around the back of the pelvis, but not all of that pain actually originates from the SI joint. A large study of over 700 adult spinal deformity patients found that while 411 reported pain near the posterior superior iliac spine (the bony bump you can feel at the back of your pelvis), only about 7 percent tested positive for SI joint pain when clinicians used specific hands-on provocation maneuvers. The strongest predictor of confirmed SI joint pain was higher body mass index, not the severity of the spinal deformity itself.³

That gap between self-reported pelvic pain and clinically confirmed SI joint pain matters. It means a sizable share of people who think their SI joint is the problem may actually have pain coming from somewhere else: a degenerated disc, a compressed nerve root, tight hip muscles, or the spinal deformity’s broader effect on posture. On the other hand, 7 percent is not trivial in a surgical population, and those patients had measurably worse disability and pain-medication use than the rest.

Adolescent Scoliosis Is a Different Story

Most of the evidence linking scoliosis to SI joint degeneration comes from adults, especially those with degenerative curves that develop later in life. Younger patients with adolescent idiopathic scoliosis generally have healthy, mobile SI joints. A study looking at patients suspected of having early inflammatory spine disease found no difference in rates of radiographic or MRI-detected sacroiliitis between those who had scoliosis and those who did not.⁴

That does not mean a teenager with scoliosis will never develop SI joint pain. It means the joint itself has not yet accumulated the wear and tear that makes it vulnerable. The risk rises with age, particularly if the curve progresses, if the person gains significant weight, or if surgical fusion eventually stiffens the segments above the SI joint. If you are a younger adult with a curve that has been stable since adolescence and your main complaint is pelvic or buttock pain, it is worth investigating other causes before assuming the SI joint is at fault.

Muscle Imbalances and Pelvic Tilt

Scoliosis does not just bend the bones. It reshapes the soft tissue around them. Case-based treatment research on adult idiopathic scoliosis found that asymmetry in key muscles, particularly the quadratus lumborum, the iliopsoas, and the latissimus dorsi, played a central role in pelvic tilt. These muscles attach at angles to the spine and pelvis, positioning them to both influence and be influenced by curvature.⁵

When the iliopsoas on one side is chronically shortened and the quadratus lumborum on the other side is overstretched, the pelvis tilts and rotates. That rotation changes how forces pass through the SI joints during standing and walking. Over months or years, the joint on the overloaded side can become irritated, stiff, or degenerative. This muscular pathway helps explain why some people with relatively mild curves still get SI joint symptoms: even a modest curve can produce enough pelvic asymmetry to tip the balance.

Why SI Joint Pain Is Hard to Pin Down in Scoliosis Patients

One of the trickiest aspects of SI joint pain in the setting of scoliosis is that it mimics other problems. Pain from the SI joint typically shows up in the low back, buttock, or back of the thigh, and it can feel a lot like sciatica from a pinched nerve. A study in the European Spine Journal examined patients with sciatica-like symptoms and found that lumbar scoliosis was more commonly present in those who turned out to have actual nerve root compression on imaging, not SI joint dysfunction. The authors emphasized that MRI of the spine is necessary to tell the two apart, because physical exam findings overlap substantially.⁶

For adult degenerative scoliosis specifically, SI joint injections serve a dual purpose. A numbing injection into the joint can confirm whether the SI joint is the pain source (if the pain disappears temporarily, the joint is likely the culprit) and provide short-term relief with a corticosteroid.⁷ If you have scoliosis and buttock or posterior thigh pain, a diagnostic injection may be the clearest way to sort out whether the SI joint is involved, rather than relying on physical exam tests alone.

Sagittal Balance and the SI Joint

Clinicians who treat spinal deformity care a great deal about sagittal balance, which is how well your spine maintains its natural front-to-back curves. When those curves flatten or exaggerate, the pelvis compensates by tilting, and the SI joints absorb the fallout. A study comparing SI joint degeneration in patients with sagittal imbalance (where the trunk leans forward) versus those with simple lumbar spinal stenosis found that the severity of SI joint degeneration correlated with pelvic incidence (a measure of pelvic anatomy) in the deformity group but not in the stenosis group.⁸

This suggests something specific about spinal deformity stresses the SI joint beyond what ordinary age-related narrowing does. A separate study found that patients who already had SI joint degeneration before corrective surgery were more likely to experience a measurable shift in their pelvic incidence after the operation, potentially because a worn SI joint is looser and allows the pelvis to remodel when the spine above it is straightened.⁹ The takeaway is that the SI joint is not a passive bystander in spinal deformity. It is part of the mechanical chain, and its condition both shapes and is shaped by surgical correction.

SI Joint Pain After Scoliosis Surgery

Surgery to correct scoliosis, especially long fusions that extend down to the sacrum, can itself become a source of new SI joint problems. This is one of the most well-documented complications in the spine surgery literature. A systematic review covering over 2,600 patients found that SI joint degenerative changes were far more common in patients who had undergone spinal fusion compared with those who had not, with rates of about 75 percent versus 38 percent on CT imaging.¹⁰

Another systematic review estimated the overall incidence of SI joint pain after lumbosacral fusion at roughly 16 percent. When the fusion extended all the way to the sacrum, that number doubled to about 33 percent.¹¹ The logic is intuitive: when you bolt several vertebrae together so they can no longer move, the joints above and below the fusion have to pick up the slack. The SI joint, sitting right at the bottom of the chain, absorbs extra motion and stress it was never designed to handle alone.

This means some scoliosis patients trade one pain source for another. Their back pain improves after corrective surgery, but a new ache develops in the pelvis months later. Surgeons increasingly factor this risk into their planning, particularly when deciding how far down a fusion should extend.

The Toll on Daily Life

People sometimes dismiss SI joint pain as minor compared with the dramatic imaging findings of scoliosis. That is a mistake. A multi-center study comparing quality-of-life scores across different spinal conditions found that patients awaiting treatment for SI joint dysfunction reported quality of life at least as low as patients preparing for surgery for disc herniation, stenosis, or degenerative spondylolisthesis.¹² SI joint pain tends to flare with transitions: getting out of a chair, rolling over in bed, climbing stairs, or standing on one leg. For someone already dealing with the postural demands of scoliosis, those aggravating activities may happen dozens of times a day.

Exercise-Based Treatment for the Pelvis and Spine Together

Conservative management for SI joint pain in the context of scoliosis needs to address both the joint and the curve. Standard SI joint rehabilitation focuses on stabilizing the pelvis with exercises for the gluteal muscles, the deep core, and the pelvic floor. When scoliosis is also present, adding curve-specific exercises can improve the muscle imbalances that tilt the pelvis in the first place.

A randomized controlled trial of adolescents with mild idiopathic scoliosis tested whether adding pelvic rotation correction to traditional Schroth exercises (a physiotherapy method designed specifically for scoliosis) would improve the balance of muscle activity on the concave versus convex sides of the curve. After 24 weeks, the group doing the combined program showed a significantly greater improvement in their concave-to-convex muscle ratio compared with the group doing Schroth exercises alone.¹³ While this trial focused on adolescents and did not measure SI joint pain directly, the principle applies: correcting pelvic rotation and balancing the muscles that control it should reduce the asymmetric loading that drives SI joint irritation.

For practical purposes, if you have scoliosis and SI joint symptoms, a physical therapist experienced with both conditions will be more useful than one who treats only one or the other. The goal is not just to calm the angry joint down but to change the mechanical environment around it so the irritation does not keep recurring.

When Surgery Targets the SI Joint Itself

If conservative measures and injections do not hold, surgical fixation of the SI joint is an option. This is most commonly considered in patients who have already had a long spinal fusion and developed new SI joint pain afterward. A case series of patients who underwent SI joint fixation following long fusions to the sacrum reported meaningful improvements: leg pain scores dropped from about 6.5 to 2.0, back pain scores fell from roughly 7.8 to 2.7, and disability scores were cut nearly in half.¹⁴

Advances in hardware are also changing the conversation around preventing SI joint problems during scoliosis correction. When surgeons need to anchor a long construct to the pelvis, they increasingly use a technique called S2 alar-iliac (S2AI) screw fixation instead of traditional iliac screws. Biomechanical research shows S2AI screws produce lower stress on both the screw and the surrounding bone while also sitting less prominently under the skin, which reduces hardware-related discomfort.¹⁵ Finite element analysis confirms that the maximum stress on S2AI screws and the bone around them is lower than with conventional iliac screws, making them a more mechanically favorable choice for spinopelvic fixation.¹⁶

When to Suspect the SI Joint and What to Ask Your Doctor

If you have scoliosis and you feel a deep, one-sided ache in the low back or buttock that worsens when you shift weight, stand from sitting, or walk on uneven ground, the SI joint deserves attention. A few questions worth raising with your provider:

• Is my pelvis level? A leg length discrepancy or pelvic obliquity can amplify SI joint stress. Sometimes this is measurable on a standing X-ray you may already have.
• Can we do provocation testing? A cluster of specific hands-on tests (distraction, compression, thigh thrust, sacral thrust, and Gaenslen’s test) is more reliable than any single test for isolating SI joint pain from other sources.
• Would a diagnostic injection help? If physical exam tests are ambiguous, a fluoroscopy-guided injection into the SI joint can clarify whether the joint is the pain generator.
• Is my fusion extending to the sacrum? If you are planning or have already had scoliosis surgery that reaches the sacrum, the risk of developing SI joint problems afterward is roughly double compared with fusions that stop higher up. This should factor into pre-surgical discussions.

Scoliosis and SI joint pain are not always a package deal, but the overlap is real and underappreciated. Addressing the spine alone while ignoring the pelvis, or treating the SI joint without accounting for spinal alignment, tends to produce incomplete results. The most effective strategies tackle the whole chain from the lumbar curve down to the pelvic ring, whether through targeted exercise, injections, or surgery designed with the SI joint in mind from the start.