Sacroiliac Joint Dysfunction: Why SI Joint Pain Is Often Missed

Written by Ifije Ohiorhenuan, MD, PhD — Board-Certified Spine Surgeon. Last updated 2026-06-20.

Sacroiliac joint dysfunction means pain is coming from one or both SI joints—the joints that connect the spine to the pelvis—but it is often missed because standard lumbar MRIs may not clearly show whether the SI joint is the pain generator.

A lumbar MRI is a scan of the lower back. It is very good at showing discs, nerves, bones, and the spinal canal. But it may not fully explain pain from the sacroiliac joint, also called the SI joint.

In my practice, SI joint pain is one of the conditions I think about when a patient has real buttock or low back pain but the lumbar MRI does not show clear nerve compression.

The key question is not, “Is the MRI normal?”
The better question is, “Do the symptoms, exam, and imaging all point to the same pain source?”

What Is Sacroiliac Joint Dysfunction?

The sacroiliac joints connect the sacrum, the triangle-shaped bone at the base of your spine, to the pelvis, the ring of bones that supports your hips and legs.

You have a right SI joint and a left SI joint.

The SI joint is small compared with the hip or knee, but it sits in a mechanically important place: where the spine transfers weight into the pelvis and legs.

These joints normally move only a small amount. But they can still become painful.

“Dysfunction” is a broad term. It may mean:

Joint irritation.
Inflammation, which means swelling or irritation in tissue.
Abnormal motion.
Degeneration, which means wear-and-tear change over time.
Pain from the joint surface.
Pain from nearby ligaments, which are strong bands of tissue that connect bones.

SI joint dysfunction is a pain diagnosis. It is not just an MRI finding.

That means doctors usually do not diagnose it from a scan alone. They look at your pain location, exam, imaging context, and sometimes response to an injection.

Where SI Joint Pain Is Usually Felt

SI joint pain can be confusing because it overlaps with several other problems.

Common pain patterns

SI joint pain is often felt in one or more of these areas:

One side of the low back.
The “dimple” area of the lower back, just off the midline.
The buttock.
The outer hip area.
The groin.
The upper thigh.

Some people feel pain that seems like sciatica. Sciatica means pain that travels down the leg from irritation or compression of a spinal nerve.

SI joint pain can feel sciatica-like, but it often does not follow a classic nerve pattern.

You can read more about true nerve-related leg pain here: Sciatica: Causes, Diagnosis, and the Treatment Path.

Symptoms that can overlap with other problems

Buttock, hip, and upper leg pain can come from many places.

SI joint pain can overlap with:

Lumbar disc herniation, which means disc material pushes out and may irritate a nerve.
Lumbar spinal stenosis, which means narrowing around the spinal nerves in the lower back.
Hip arthritis or hip labral problems. The labrum is a ring of cartilage around the hip socket.
Piriformis or deep gluteal pain. The piriformis is a small muscle deep in the buttock.
Facet joint pain. Facet joints are small joints in the back of the spine.
Muscle strain.

This is why symptoms alone are not enough to prove the SI joint is the cause.

Why Sacroiliac Joint Dysfunction Is Often Missed

One reason SI joint pain is missed is that patients and doctors often focus heavily on the lumbar MRI report. But the MRI report may describe several age-related spine findings while saying very little about the SI joints themselves.

A standard lumbar MRI is mainly focused on:

Discs.
Nerves.
Vertebrae, which are the bones of the spine.
The spinal canal, which is the space that holds the nerves.
Areas where nerves exit the spine.

It is not always designed to fully evaluate the SI joints.

Also, SI joint pain often does not create a dramatic MRI finding. You can have significant pain without a scan showing a clear “smoking gun.”

At the same time, lumbar MRI reports often show mild disc bulges or degenerative changes. These findings can be real, but they may not be the main pain source.

Disc bulges and degenerative changes are common as people age. They can even appear in people who do not have back pain.

That does not mean MRI findings should be ignored. It means they must be matched to the story.

In my practice, what I look for on MRI is not just whether there are disc bulges, but whether the imaging findings actually match the patient’s pain pattern.

For more on age-related MRI findings, see Degenerative Disc Disease: What “Normal Aging” Looks Like on Your MRI.

What Causes SI Joint Dysfunction?

SI joint pain can have more than one cause. It is not always a simple “misalignment” problem.

Common contributors

Possible contributors include:

Prior trauma or a fall.
Pregnancy or postpartum changes. Postpartum means after childbirth.
Ligament looseness or pelvic load changes during or after pregnancy.
Prior lumbar fusion. Fusion means surgery that joins two or more spine bones together.
Degenerative joint changes.
Inflammatory arthritis, such as ankylosing spondylitis, a disease that can inflame the spine and SI joints.
Other spondyloarthropathies, which are arthritis conditions that can affect the spine and pelvis.
Leg length difference.
Altered gait. Gait means the way you walk.
Repetitive mechanical stress.
Sometimes no single clear cause.

After lumbar fusion, some patients develop or continue to have pain that may come from the SI joint. This can happen because more stress may be transferred to the pelvis.

But not all pain after spine surgery is SI-related. Other causes still need to be considered.

How Doctors Diagnose SI Joint Pain

SI joint dysfunction is usually diagnosed by putting several pieces together.

No single symptom, test, or scan proves it by itself.

History and pain location

The history means the story of your symptoms.

Doctors look at:

Where the pain is felt.
Whether it is mostly on one side.
What movements make it worse.
Whether it travels below the knee.
Whether numbness, tingling, or weakness is present.
Whether the pattern sounds more like nerve compression, hip disease, or SI joint pain.

Common SI-region triggers can include stairs, standing on one leg, getting in and out of a car, rolling in bed, prolonged standing, or moving from sitting to standing.

These triggers can raise suspicion. They do not diagnose the condition by themselves.

Physical exam maneuvers

Doctors may use hands-on tests that place stress across the SI joint. These are called provocative tests because they try to reproduce your familiar pain.

Common SI joint provocative tests include:

FABER/Patrick test: the hip is placed in a figure-four position to stress the hip and SI area.
Thigh thrust: pressure is applied through the thigh to load the SI joint.
Compression test: the pelvis is gently compressed from the side.
Distraction test: the front of the pelvis is gently stressed apart.
Gaenslen test: the hips are positioned to stress one side of the pelvis.
Sacral thrust: pressure is applied over the sacrum.

No single physical exam test is perfect.

A cluster of positive tests is more useful than one isolated test. The finding matters most when the pain location, exam maneuvers, and response to diagnostic injection all point in the same direction.

Imaging

Imaging means tests that create pictures of the inside of the body.

A lumbar MRI may help show or rule out competing causes, such as:

Disc herniation.
Spinal stenosis.
Nerve compression.
Fracture.
Tumor or infection in certain settings.

Sometimes doctors may order other imaging, such as:

Pelvic X-rays.
Dedicated SI joint X-rays.
CT scan, which is a detailed bone scan.
Dedicated SI joint MRI.
Pelvic MRI.

SI joint imaging may show:

Arthritis.
Inflammation.
Sclerosis, which means hardening or thickening of bone near a joint.
Erosions, which are small areas of bone loss from inflammation.
Partial or complete fusion of the joint.

But imaging alone does not always prove the SI joint is the pain source.

Diagnostic injection

A diagnostic injection is an injection used to help identify where pain is coming from.

For suspected SI joint pain, doctors may use an image-guided SI joint injection. Image-guided means X-ray or CT is used to help place the needle accurately.

The injection often includes a local anesthetic, which is numbing medicine.

If numbing the SI joint temporarily relieves your typical pain, that can support the SI joint as the pain generator. But it is not a perfect test.

Doctors look at:

How much relief occurred.
How quickly relief started.
How long relief lasted.
Whether the relief matched the expected action of the numbing medicine.
Whether the treated pain was the same pain you usually feel.

The result should be interpreted in the full clinical context.

SI Joint Dysfunction vs Disc Herniation, Sciatica, Hip Pain, and Spinal Stenosis

In my practice, I am cautious about blaming the SI joint too quickly, because hip disease, lumbar stenosis, and disc herniations can all create overlapping symptoms.

SI joint pain vs lumbar disc herniation

A lumbar disc herniation means the soft inner part of a spinal disc pushes outward through the tougher outer layer.

A disc herniation often causes nerve-root symptoms. A nerve root is a nerve branch that exits the spine.

This can cause pain, numbness, tingling, or weakness down the leg in a more specific pattern.

SI joint pain more often stays in the low back, buttock, hip, groin, or upper thigh. But overlap can happen.

Learn more here: Lumbar Disc Herniation: A Surgeon’s Patient Guide.

SI joint pain vs sciatica

True sciatica usually involves irritation or compression of a lumbar nerve root.

SI joint pain can feel like radiating leg pain. It may spread into the buttock or upper leg. But it may not involve nerve compression.

More detail is available here: Sciatica: Causes, Diagnosis, and the Treatment Path.

SI joint pain vs lumbar spinal stenosis

Lumbar spinal stenosis means narrowing around the spinal nerves in the lower back.

Stenosis often causes leg symptoms with standing or walking. Many people feel better when sitting or bending forward.

SI joint pain is often more localized. It may worsen with transitions, stairs, or loading one side of the pelvis.

SI joint pain vs hip disease

Hip joint pain often shows up in the groin. It may worsen when the hip is rotated.

SI joint pain is often more posterior. Posterior means toward the back of the body. It is often felt near the buttock or low back dimple area.

But the overlap can be substantial. Some people need both the hip and spine/SI region evaluated.

Treatment Options for Sacroiliac Joint Dysfunction

Treatment depends on how strong the diagnosis is, how severe the symptoms are, and what else is going on.

Before discussing procedures like ablation or fusion, I want to see a consistent story: the symptoms, exam, imaging review, and diagnostic response should all support the SI joint as the main pain generator.

Conservative care

Conservative care means non-surgical treatment.

Many people start with:

Activity changes.
Physical therapy.
Anti-inflammatory medicines when appropriate and safe.
Heat or ice.
Short-term symptom control.
Work on walking mechanics.

Physical therapy may focus on:

Pelvic stability.
Hip strength.
Core control. The core means the muscles around the abdomen, back, and pelvis.
Gait mechanics.
Safe movement during stairs, transfers, and lifting.

Physical therapy should be individualized. A movement that helps one person may flare another person.

SI joint injections

An SI joint injection may be used for diagnosis, treatment, or both.

A steroid injection uses anti-inflammatory medicine to calm irritated tissue. It may reduce pain for some people.

Relief varies. Some people get short-term relief. Some get longer relief. Some get little relief.

A future SpineClarity guide will compare SI joint injection vs radiofrequency ablation.

Radiofrequency ablation

Radiofrequency ablation, often called RFA, is a procedure that uses heat energy to target small sensory nerve branches around the SI joint.

Sensory nerves are nerves that carry pain signals.

RFA does not repair, rebuild, or realign the SI joint. It is meant to reduce pain signaling.

It may be considered in selected patients when diagnostic blocks suggest SI-mediated pain.

SI joint fusion

SI joint fusion is surgery that joins the SI joint so it moves less.

Fusion is generally reserved for carefully selected patients who have:

Persistent, function-limiting SI joint pain.
Symptoms that have not improved with non-surgical care.
Exam findings that fit SI joint pain.
Imaging review that does not show a better explanation.
Diagnostic evidence supporting the SI joint as the pain source.

Fusion is not common for every person with SI pain. It is not the first step for most people.

A future SpineClarity guide will explain when SI joint fusion is considered.

When SI Joint Pain Is Not the Whole Story

A person can have SI joint pain and lumbar spine changes at the same time.

MRI findings such as disc bulges, facet arthritis, stenosis, or degenerative disc disease may or may not be the main pain generator.

The goal is not to name every MRI abnormality. The goal is to match the findings with the symptoms and exam.

Other spine conditions can also overlap with SI-region pain, including:

Spondylolisthesis, which means one spine bone has slipped compared with the one below it.
Adult degenerative scoliosis, which means an adult spine curve related to wear-and-tear changes.
Vertebrogenic pain, which means pain coming from irritated bone and nerve endings near the spinal endplates. Endplates are the top and bottom surfaces of a spinal bone next to the disc.

This is why a careful review matters. Pain generators can overlap.

After Diagnosis: What to Do If Your MRI Does Not Explain Your Pain

If you have been told your lumbar MRI is “mild” or “normal,” but your pain pattern still sounds like it could be SI joint-related, the next step is often to put the MRI report, symptoms, and prior treatments into one clear clinical picture.

It can be frustrating when your pain is severe but your report says:

“Mild degenerative changes.”
“No significant stenosis.”
“Small disc bulge.”
“No clear nerve compression.”

That does not mean your pain is not real.

It means the MRI may not be showing the whole story. The pain source could still be in the spine, hip, SI joint, muscles, tendons, or a combination of areas.

SpineClarity offers a written MRI/case review from a board-certified spine surgeon. You can upload your symptoms, MRI report, and relevant records and receive a plain-language written interpretation with a suggested next-step category.

This is not emergency care and does not replace an in-person physician relationship, but it can help you understand whether your imaging findings seem to match your symptoms—or whether another pain source, such as the SI joint, may need to be considered.

Red Flags: When to Seek Urgent Medical Care

SI joint dysfunction is usually not an emergency by itself.

But certain symptoms are not typical SI joint pain and need urgent evaluation.

Seek urgent medical care or emergency evaluation if you have:

New or worsening leg weakness.
Loss of bowel or bladder control.
Numbness in the groin, inner thighs, or saddle area.
Fever, chills, or concern for infection.
History of cancer with new severe spine or pelvic pain.
Major trauma or a fall.
Unexplained weight loss with worsening pain.
Severe, rapidly worsening pain.
Inability to walk or stand safely.

Loss of bowel or bladder control, saddle numbness, or severe new neurologic symptoms can be signs of a spine emergency called cauda equina syndrome. Cauda equina syndrome means the bundle of nerves at the bottom of the spinal canal is being compressed.

Learn more here: Cauda Equina Syndrome: The Spine Emergency Patients Need to Recognize.

Frequently Asked Questions

Can sacroiliac joint dysfunction show up on MRI?

Sometimes.

Dedicated SI joint imaging may show inflammation, arthritis, sclerosis, erosions, or joint fusion. But many cases of SI-mediated pain are not obvious on a standard lumbar MRI.

A lumbar MRI is mainly built to look at the lower spine, discs, nerves, and spinal canal. It may not confirm or exclude SI joint pain.

Can SI joint pain feel like sciatica?

Yes, it can.

SI joint pain can cause buttock or upper leg pain that feels sciatica-like. But true sciatica usually means a lumbar nerve root is irritated or compressed.

That difference matters because the treatment path may be different.

How do doctors confirm SI joint pain?

Doctors usually combine several pieces:

Symptom history.
Pain location.
Physical exam.
SI joint provocative tests.
Imaging context.
Sometimes an image-guided diagnostic SI joint injection.

The diagnosis is stronger when several pieces point to the same source.

Is sacroiliac joint dysfunction serious?

SI joint dysfunction is usually not dangerous. But it can be very painful and can limit walking, sitting, sleep, work, and daily life.

It is not usually an emergency unless red flags are present, such as new weakness, loss of bowel or bladder control, saddle numbness, fever, cancer history with new severe pain, major trauma, or inability to walk.

What makes SI joint pain worse?

Some people notice worse pain with:

Stairs.
Standing on one leg.
Getting in or out of a car.
Rolling in bed.
Prolonged standing.
Moving from sitting to standing.

These patterns can raise suspicion for SI-region pain, but they are not diagnostic by themselves.

Can physical therapy help SI joint dysfunction?

Yes, physical therapy can help many people.

It is often most useful when it is tailored to your pain pattern and focuses on hip strength, core control, pelvic stability, and movement mechanics.

A generic exercise list may not fit every person.

When is SI joint fusion considered?

SI joint fusion is generally considered only for carefully selected patients.

Usually, that means persistent function-limiting pain, unsuccessful conservative care, exam findings that fit SI pain, and diagnostic evidence that the SI joint is the main pain source.

Fusion is not the first step for most people with SI-region pain.

Why did my MRI show disc degeneration if my doctor thinks the SI joint is the problem?

Disc degeneration is common, especially with age. It can appear even in people without back pain.

That does not mean it is always harmless or always important. It means the MRI finding must be matched to your symptoms and exam.

Sometimes the disc finding explains the pain. Sometimes it does not. Sometimes more than one pain source is present.

References

Brinjikji, W., Luetmer, P. H., Comstock, B., et al. (2015). Systematic literature review of imaging features of spinal degeneration in asymptomatic populations. AJNR American Journal of Neuroradiology, 36(4), 811–816.

Cohen, S. P. (2005). Sacroiliac joint pain: A comprehensive review of anatomy, diagnosis, and treatment. Anesthesia & Analgesia, 101(5), 1440–1453.

Cohen, S. P., Chen, Y., Neufeld, N. J., et al. (2024). Consensus practice guidelines on sacroiliac joint pain from a multispecialty, international working group. Regional Anesthesia & Pain Medicine.

Cohen, S. P., Hurley, R. W., Buckenmaier, C. C. III, Kurihara, C., Morlando, B., & Dragovich, A. (2008). Randomized placebo-controlled study evaluating lateral branch radiofrequency denervation for sacroiliac joint pain. Anesthesiology, 109(2), 279–288.

Hansen, H. C., McKenzie-Brown, A. M., Cohen, S. P., Swicegood, J. R., Colson, J. D., & Manchikanti, L. (2012). A systematic evaluation of the therapeutic effectiveness of sacroiliac joint interventions. Pain Physician, 15(3), E247–E278.

Jensen, M. C., Brant-Zawadzki, M. N., Obuchowski, N., Modic, M. T., Malkasian, D., & Ross, J. S. (1994). Magnetic resonance imaging of the lumbar spine in people without back pain. New England Journal of Medicine, 331(2), 69–73.

Laslett, M. (2008). Evidence-based diagnosis and treatment of the painful sacroiliac joint. Journal of Manual & Manipulative Therapy, 16(3), 142–152.

Lorio, M. P., & Rashbaum, R. (2014). ISASS policy statement—Minimally invasive sacroiliac joint fusion. International Journal of Spine Surgery, 8, 25.

Maigne, J. Y., & Planchon, C. A. (2005). Sacroiliac joint pain after lumbar fusion: A study with anesthetic blocks. European Spine Journal, 14(7), 654–658.

National Institute of Arthritis and Musculoskeletal and Skin Diseases. Ankylosing spondylitis. NIH/NIAMS.

Polly, D. W., Cher, D. J., Wine, K. D., Whang, P. G., Frank, C. J., & Harvey, C. F. (2015). Randomized controlled trial of minimally invasive sacroiliac joint fusion using triangular titanium implants vs nonsurgical management for sacroiliac joint dysfunction: 12-month outcomes. Neurosurgery, 77(5), 674–690.

Qaseem, A., Wilt, T. J., McLean, R. M., Forciea, M. A., & Clinical Guidelines Committee of the American College of Physicians. (2017). Noninvasive treatments for acute, subacute, and chronic low back pain: A clinical practice guideline from the American College of Physicians. Annals of Internal Medicine, 166(7), 514–530.

American College of Radiology. (2021). ACR Appropriateness Criteria®: Low back pain—2021 update. Journal of the American College of Radiology, 18(11S), S361–S379.

Slipman, C. W., Jackson, H. B., Lipetz, J. S., Chan, K. T., Lenrow, D., & Vresilovic, E. J. (2000). Sacroiliac joint pain referral zones. Archives of Physical Medicine and Rehabilitation, 81(3), 334–338.

Szadek, K. M., van der Wurff, P., van Tulder, M. W., Zuurmond, W. W., & Perez, R. S. G. M. (2009). Diagnostic validity of criteria for sacroiliac joint pain: A systematic review. The Journal of Pain, 10(4), 354–368.

Vleeming, A., Albert, H. B., Ostgaard, H. C., Sturesson, B., & Stuge, B. (2008). European guidelines for the diagnosis and treatment of pelvic girdle pain. European Spine Journal, 17(6), 794–819.