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SI Joint Dysfunction

SI joint dysfunction causes pain low in the back and buttock that is often mistaken for sciatica — diagnosed with image-guided joint injection at Remix Medical in Houston.

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By Raju Mantena, DO · Pain Medicine PhysicianReviewed Jul 31, 20262 min read

Ask a patient with sacroiliac joint pain to point at it and they will usually place one finger just below the belt line, off to one side. Ask them what they have been treated for and they will usually say sciatica. At Remix Medical in Houston, our pain management physicians use image-guided diagnostic injection to establish whether the SI joint is the actual source before committing to a treatment plan.

What is SI Joint Dysfunction?

The sacroiliac joints connect the sacrum, at the base of the spine, to the iliac bones of the pelvis. They move very little — a few millimeters — but they transfer the entire load of the upper body into the legs.

When a sacroiliac joint becomes inflamed, or when it moves too much or too little, it generates pain in the low back, buttock, groin, and sometimes down the back of the thigh. Because that pattern overlaps heavily with lumbar disc pain, the joint is frequently overlooked.

SI joint dysfunction accounts for a meaningful share of chronic low back pain, and a larger share among patients who have already had lumbar fusion.

Common Causes of SI Joint Dysfunction

1. Prior Lumbar Fusion

Fusing segments of the lumbar spine transfers load to the joints immediately below. The SI joint absorbs it.

2. Pregnancy and Childbirth

Hormonal ligament laxity, weight gain, and altered gait all stress the joint. Symptoms can persist well after delivery.

3. Trauma

A fall onto the buttock, a motor vehicle collision, or a hard landing can injure the joint and its supporting ligaments.

4. Leg Length Discrepancy and Gait Asymmetry

Asymmetric loading over years wears one joint disproportionately.

5. Inflammatory Arthritis

Ankylosing spondylitis and related conditions inflame the SI joints directly, often in younger patients with morning stiffness.

How Remix Medical Can Help

Physical examination maneuvers help, but no single test is definitive. The reference standard is a diagnostic injection: local anesthetic placed into the joint under fluoroscopic guidance. If your familiar pain substantially resolves, the joint is confirmed as the pain generator.

Because single blocks carry false positives, dual comparative blocks improve diagnostic accuracy before committing to anything longer-lasting.

ApproachWhat it involves
Physical therapy + bracingHip and core stabilization, with a supportive SI belt
Medication managementAnti-inflammatories for symptom control
Fluoroscopically guided SI joint injectionBoth diagnostic and therapeutic — confirms the joint as the source and calms it
Radiofrequency ablationLateral branch ablation for durable relief when injections help but fade
Chiropractic and soft-tissue therapyThrough our in-house team when a mechanical component is present

Signs & symptoms

Signs and symptoms to watch for

  • Pain below the belt line, usually on one side
  • Buttock pain, and sometimes groin pain
  • Referred pain down the back of the thigh, typically stopping above the knee
  • Worse when standing from a seated position, climbing stairs, or rolling over in bed
  • Difficulty sitting for long periods or sitting evenly on both sides
  • A sense of instability or catching in the pelvis

When to see a specialist

Should you see a specialist?

See a pain specialist if pain sits low and to one side of the back — often pointed to with a single finger just below the belt line — and worsens with standing from a chair, climbing stairs, or rolling in bed. SI joint pain is commonly treated as sciatica for months before the joint is ever examined. Seek immediate care for new leg weakness, numbness in the groin or inner thighs, or loss of bladder or bowel control; pain with fever or after significant trauma needs prompt evaluation.

Treatment options

Possible treatments

Frequently asked

SI Joint Dysfunction questions, answered

What does SI joint pain feel like?

Usually a deep ache low in the back or buttock, sometimes spreading into the hip or upper thigh. It often flares with standing up, climbing stairs, or rolling over in bed.

How is SI joint dysfunction diagnosed?

It's diagnosed by exam maneuvers that stress the joint, and confirmed when a numbing injection into the joint relieves the pain. Imaging helps rule out other causes.

Can SI joint pain be treated without surgery?

Yes, most cases respond to physical therapy, a support belt, and anti-inflammatory measures. If injections help but wear off, radiofrequency ablation can give longer relief.

What is SI joint dysfunction?

It's pain from the sacroiliac joint, where the spine meets the pelvis. When that joint moves too much or too little, it causes low-back and buttock pain, often on one side.

When should SI joint pain be checked urgently?

New leg weakness, numbness in the groin or inner thighs, or loss of bladder or bowel control is an emergency and needs immediate care, since it points to something beyond the SI joint.

Why is SI joint pain so often mistaken for sciatica?

Because the pain pattern overlaps heavily with lumbar disc pain — low back, buttock, groin, and sometimes down the back of the thigh. Patients are frequently treated for sciatica for months before the SI joint is ever examined. A telling clue is that people often point to it with a single finger just below the belt line, off to one side.

What raises the risk of SI joint dysfunction?

Prior lumbar fusion (which transfers load to the joint), pregnancy and childbirth, trauma such as a fall onto the buttock, leg-length discrepancy and gait asymmetry, and inflammatory arthritis like ankylosing spondylitis.

How long does SI joint ablation last?

Studies show substantial proportions of well-selected patients achieve meaningful relief at 6 and 12 months after lateral branch ablation, particularly when anatomically validated techniques are used.

Sources

References

  1. Chen AS, Solberg J, Smith C, et al. Radiofrequency Ablation for Chronic Posterior Sacroiliac Joint Complex Pain: A Comprehensive Review (Spine Intervention Society). Pain Med 2021;22(Suppl 1):S9–S13 — https://academic.oup.com/painmedicine/article/22/Supplement_1/S9/6328212
  2. Raj MA, Ampat G, Varacallo M. Sacroiliac Joint Pain. StatPearls. NCBI Bookshelf — https://www.ncbi.nlm.nih.gov/books/NBK470299/
  3. Cohen SP, Chen Y, Neufeld NJ. Sacroiliac joint pain: a comprehensive review of epidemiology, diagnosis and treatment. Expert Rev Neurother 2013;13(1):99–116 — https://doi.org/10.1586/ern.12.148
  4. Chuang CW, Hung SK, Pan PT, Kao MC. Diagnosis and interventional pain management options for sacroiliac joint pain. Ci Ji Yi Xue Za Zhi 2019;31(4):207–210 — https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6905244/
  5. National Institute of Arthritis and Musculoskeletal and Skin Diseases: Back Pain — https://www.niams.nih.gov/health-topics/back-pain
  6. National Institute of Neurological Disorders and Stroke: Low Back Pain — https://www.ninds.nih.gov/health-information/disorders/back-pain

Your care team

Clinicians who treat this.

Every clinician at Remix Medical is board-certified and owns the practice — so the physician in your exam room is the one making decisions about your care.

  • Raju Mantena, DO

    Raju Mantena, DO

    Pain Medicine Physician

    4.8 · 118 Google reviews

    Accepting New Patients

  • Alham Samani, DC

    Alham Samani, DC

    Doctor of Chiropractic

    4.9 · 122 Google reviews

    Accepting New Patients

Care pathwayChiropractic · Interventional PainICD-10 codeM53.3Associated anatomySacroiliac joint, sacrum, ilium, posterior superior iliac spine, sacroiliac ligaments

Also called Sacroiliac Joint Dysfunction, Sacroiliitis, SI Joint Pain, Sacroiliac Joint Syndrome

This page is for general education and is not a substitute for medical advice from your physician. Contact a Remix Medical clinician about your specific situation.

Updated July 31, 2026. Medically reviewed by Raju Mantena, DO.

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