SI Joint Pain: Is the Pain Really Coming From Your SI Joint?

Pain near the dimples at the bottom of your back is often labeled “SI joint pain.”

Sometimes that diagnosis is correct. But the location of pain alone does not tell us which structure is causing it.

The sacroiliac joints, usually shortened to SI joints, connect the sacrum at the base of your spine to the two sides of your pelvis. They help transfer force between your upper body and legs and move only a very small amount. Although these joints can become painful, SI joint problems are also commonly overdiagnosed.

Why? Because pain from the lower back, discs, hips, muscles, nerves, and other nearby structures can all be felt in the same general area.

What Does SI Joint Pain Usually Feel Like?

True SI joint pain is most often felt on one side, close to the bony “dimple” just below the beltline. When asked to point to the pain with one finger, a person with SI joint pain will often point directly to this area. This is sometimes called the Fortin finger sign.

Pain can also spread into:

• The buttock

• The side or back of the thigh

• The groin

• The lower back

• More rarely, the lower leg

The exact distribution varies. Irritation near the upper part of the joint tends to cause pain near the back of the pelvis, while irritation lower in the joint may be felt lower in the buttock. Groin pain is also more common than many people realize.

Symptoms may increase with:

• Standing or walking for a long time

• Putting most of your weight on the painful side

• Getting up from a chair

• Rolling over in bed

• Climbing stairs

• Getting into or out of a vehicle

• Taking a long car ride

• Bending forward while standing

These clues can raise suspicion for SI joint pain, but none of them proves the diagnosis. Many lower-back and hip conditions behave in similar ways.

Why Is SI Joint Pain Overdiagnosed?

A sore spot near the SI joint is not automatically an SI joint problem. The joint sits in a busy neighborhood, and pain is not always felt directly over the structure producing it.

Pain from the lumbar spine, especially disc-related pain, can refer into the same area. In fact, a large percentage of pain felt around the SI joint may actually be referred from the lower back. Disc-related pain can also make SI joint provocation tests appear positive, even when the disc is the main source of the problem.

This is one reason statements such as “your pelvis is out,” “one hip is rotated,” or “your SI joint is stuck” should not be accepted as a complete diagnosis based on one quick test.

Small differences in posture, leg length, or pelvic position are common. Motion testing and palpation may provide information, but they are not dependable enough to diagnose a painful SI joint by themselves.

Imaging does not automatically settle the question either. Arthritis and degeneration of the SI joints can be seen in people who have no pain at all. An X-ray, CT, or MRI finding must match the history and physical examination. A picture showing wear and tear does not prove that the finding is responsible for the patient’s symptoms.

How Should SI Joint Pain Be Evaluated?

There is no single movement, tender point, orthopedic test, or imaging finding that can diagnose SI joint pain with confidence.

A better evaluation starts by comparing several possible sources. That should include the lumbar spine, hips, nerves, muscles, and SI joint.

t may also include repeated movement testing to see whether symptoms move, centralize, or improve with specific lower-back movements. If pain near the SI joint changes or moves toward the center of the back during lumbar testing, the lower back is more likely to be the source.

For the SI joint itself, a cluster of pain-provocation tests is more useful than one test in isolation. Common tests include distraction, thigh thrust, compression, and sacral thrust. The tests are considered meaningful when they reproduce the patient’s familiar pain, not simply because pressure feels uncomfortable.

The full picture matters:

• Is the pain mainly on one side and close to the SI joint?

• Do multiple SI joint provocation tests reproduce the same familiar pain?

• Has the lumbar spine been evaluated as a possible source?

• Is the hip contributing?

• Is the neurologic examination normal?

• Did the problem begin after a fall, pregnancy, a change in gait, or another clear stressor?

• Are there signs suggesting inflammation, fracture, infection, or another condition needing further investigation?

When the diagnosis remains uncertain and symptoms are severe or persistent, an image-guided anesthetic injection may be used by a specialist to help confirm whether the SI joint is truly the pain generator.

When Might the SI Joint Actually Be the Problem?

Mechanical SI joint pain may follow a fall onto the buttocks, repetitive loading, pregnancy, altered walking mechanics, or pain in another lower-extremity joint. It can also become more likely after lumbar fusion because additional force may be transferred to the SI joint.

Not all SI joint pain is mechanical. Inflammatory conditions such as ankylosing spondylitis, psoriatic arthritis, reactive arthritis, and arthritis associated with inflammatory bowel disease can cause sacroiliitis.

and stiffness lasting longer than 30 minutes in the morning and improving with movement deserve a closer look, especially when accompanied by other inflammatory symptoms.

Stress fractures of the sacrum can also mimic SI joint or lower-back pain, including in young athletes. Older adults with osteoporosis may develop insufficiency fractures.

Significant trauma, unexplained night pain, fever, progressive weakness, bowel or bladder changes, unexplained weight loss, or pain that is rapidly worsening should prompt further evaluation and, when appropriate, imaging or referral.

What Does Treatment Look Like?

When the SI joint is the likely source, most cases should begin with conservative care. Treatment may include:

• Manual therapy or manipulation when a meaningful movement restriction is present

• Exercises that improve trunk, hip, and pelvic control

• Gradual loading and a return to normal activity

• Addressing relevant gait, hip, foot, or lower-extremity problems

• Short-term use of an SI belt in selected cases, particularly when instability is suspected

• Education about positions and activities that temporarily aggravate symptoms

• In some cases focused shockwave, laser, and/or dry needling can be beneficial

  
  

An adjustment may reduce pain, but repeatedly “putting the joint back in place” is not a complete long-term strategy. The goal should be to improve function, build tolerance, and give the patient tools to manage the problem independently.

Persistent cases may require additional investigation or referral for an image-guided injection, radiofrequency treatment, or, much less commonly, surgery. Those options make the most sense only after the diagnosis has been established carefully and reasonable conservative care has failed.

The Bottom Line

SI joint pain exists, but it should not become the default label for every ache on one side of the lower back or buttock.

The location of pain is a clue, not a diagnosis. A thorough evaluation should try to reproduce the familiar symptoms, test the lower back and hips, screen the nervous system, and look for less common but important causes.

The right diagnosis matters because an SI joint, lumbar disc, hip, stress fracture, and inflammatory condition should not all be treated the same way.

At Marathon Spine & Wellness, our goal is not simply to name the sore spot. We work to identify what is driving the pain, explain what we find, and build a treatment plan aimed at getting you back to normal activity without unnecessary imaging, injections, or endless appointments.

This article is for general education and is not a substitute for an individual medical evaluation.

Selected References

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

2. DePhillipo NN, et al. Sacroiliac pain: structural causes of pain referring to the SI joint region. Clinical Spine Surgery. 2019;32(6):E282–E288.

3. Eno JJ, et al. The prevalence of sacroiliac joint degeneration in asymptomatic adults. Journal of Bone and Joint Surgery. 2015;97(11):932–936.

4. Kurosawa D, Murakami E, Aizawa T. Referred pain location depends on the affected section of the sacroiliac joint. European Spine Journal. 2015;24(3):521–527.

5. Vanaclocha V, et al. Diagnostic accuracy of clinical examination to distinguish sacroiliac joint pain as a cause of chronic low back pain. British Journal of Neurosurgery. Published online December 9, 2024.

6. Nejati P, Safarcherati A, Karimi F. Effectiveness of exercise therapy and manipulation on sacroiliac joint dysfunction: a randomized controlled trial. Pain Physician. 2019;22(1):53–61.