Sacroiliac Joint Dysfunction

What is the sacroiliac (SI) joint?

The sacroiliac (SI) joint is the largest axial joint in the body, connecting the sacrum (base of the spine) to the ilium (part of the pelvis). You have two SI joints—one on each side, deep in the lower back. The joint surfaces are irregular and tightly bound by some of the strongest ligaments in the body, which makes them extremely stable. Cartilage lines the joint surfaces—hyaline cartilage on the sacrum and fibrocartilage on the ilium—helping the joint withstand heavy forces.

Function & Biomechanical Role:
The SI joint serves as a bridge between the spine and legs, transferring the weight of the upper body into the pelvis and lower extremities. While it only allows for a few millimeters of movement, that small motion plays an important role in absorbing shock and reducing stress on the spine and hips. During walking, running, and bending, the SI joints help stabilize the body, and in pregnancy they adapt by becoming slightly more flexible to allow for childbirth.

Clinical Importance:
Because the SI joints bear so much load and stress, they are a common source of low back and pelvic pain. Problems can arise from inflammation (sacroiliitis), arthritis, trauma, or ligament strain. Symptoms often mimic hip or lumbar spine problems, sometimes making diagnosis tricky. Recognizing SI joint dysfunction is important because effective treatments—from physical therapy and injections to minimally invasive procedures—can significantly improve pain and mobility.

What is sacroiliac joint dysfunction?

Sacroiliac joint dysfunction (SIJD) refers to pain and impaired function originating from one or both sacroiliac joints and their supporting ligaments when they become inflamed, arthritic, or hyper-/hypo-mobile. This often occurs after repetitive stress, trauma such as a motor vehicle accident or fall, or changes in mechanics after spine or hip surgery. The result is pain that may be felt in the lower back, buttocks, hips, or groin. Seeking expert evaluation is crucial to accurately identify sacroiliac joint dysfunction as it commonly mimics other low back conditions such as sciatica, disc disorders, or hip arthritis which often leads to misdiagnosis and delayed treatment.

Common symptoms & patterns

• Deep, aching pain in the lower back, buttock, or posterior hip (often one-sided; sometimes both).
• Pain that worsens with transitional movements such as getting in/out of a car, getting in/out of bed, rolling over in bed, prolonged standing/walking, prolonged sitting.
• Referral into the groin, buttock, hip, or back of the thigh (usually not below the knee).
• Sensation of pelvic “stiffness” or instability of the affected leg; difficulty with transitional movements.
• Tenderness over the upper buttock (able to point directly to spot = “Fortin sign”

Seek urgent care for red-flags such as new leg weakness, numbness in the groin/saddle area, loss of bowel or bladder control, fever with severe back pain, or pain after significant trauma.

Causes & risk factors

Common causes

• Inflammation of the joint (sacroiliitis) or surrounding ligaments
• Osteoarthritis or degenerative joint changes
• Trauma (falls, sports injuries, auto accidents)
• Repetitive stress, heavy lifting, or prolonged asymmetrical postures
• Pregnancy/postpartum changes (increased ligament laxity)
• Prior lumbar fusion or hip pathology altering load through the pelvis

Risk factors

• Occupations or sports with repetitive twisting/lifting
• Leg length difference or gait abnormalities
• Inflammatory arthropathies (e.g., spondyloarthropathy)
• Age-related cartilage wear
• History of hip or spine surgery, particularly lumbar fusion

How we diagnose SI joint pain

At Pain & Vascular Institute, we combine a careful history with targeted physical examination and imaging when appropriate. Provocative maneuvers (such as distraction, compression, thigh thrust, Gaenslen, and FABER) help reproduce your typical pain and point toward the SI joint. When needed, image-guided diagnostic injections—placing a small amount of numbing medicine into the SI joint—can confirm the SI joint as the pain generator.

Treatment options

Most patients improve with a stepwise, minimally invasive plan tailored to their goals and lifestyle:

• Activity modification & home care: short-term rest from provoking activities, heat/ice, ergonomic adjustments.
• Physical therapy: stabilization of the core and pelvic girdle, manual therapy, and gait/posture training.
• Medications: short courses of anti-inflammatories or other pain-modulating options when appropriate.
• Supportive bracing: pelvic or SI belts in select cases to enhance stability during healing.
• Image-guided SI joint injections: corticosteroid and local anesthetic to reduce inflammation and provide relief.
• Radiofrequency ablation (RFA): targeted treatment of sensory nerves to offer longer-lasting pain control when injections are short-lived.
• Minimally invasive SI joint fusion: considered for persistent, well-documented SI joint–mediated pain that does not respond to conservative care.

Why choose Pain & Vascular Institute

Our interventional pain specialists offer evidence-based, minimally invasive care with advanced imaging guidance. We serve patients in Fox River Grove, Barrington, Lake Barrington, Cary, and surrounding northwest Chicago suburbs.

Ready to get started? Call our Fox River Grove office or request an appointment online. (Insert practice phone/email/booking link.)

Medical information disclaimer

This page provides general information and is not a substitute for personalized medical advice. If you have severe or worsening symptoms, please seek medical care promptly.

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What Is the Sacroiliac Joint?

The sacroiliac (SI) joint  sit at the base of your spine, connecting the sacrum (the triangular bone beneath the lumbar spine) to the iliac bones of your pelvis. These joints are small but powerful—responsible for transferring weight between your upper body and legs.

Although the SI joints only move a few millimeters, they play a critical role in stability, posture, and walking. Strong ligaments hold them in place, and even small changes in their function can cause significant pain.

natomy & Structure:
The sacroiliac (SI) joint is the largest axial joint in the body, connecting the sacrum (the triangular bone at the base of the spine) to the ilium (part of the pelvis). You have one SI joint on each side, deep in the lower back. The joint surfaces are irregular and tightly bound by some of the strongest ligaments in the body, which makes them extremely stable. Cartilage lines the joint surfaces—hyaline cartilage on the sacrum and fibrocartilage on the ilium—helping the joint withstand heavy forces.

Function & Biomechanical Role:
The SI joint serves as a bridge between the spine and legs, transferring the weight of the upper body into the pelvis and lower extremities. While it only allows for a few millimeters of movement, that small motion plays an important role in absorbing shock and reducing stress on the spine and hips. During walking, running, and bending, the SI joints help stabilize the body, and in pregnancy they adapt by becoming slightly more flexible to allow for childbirth.

Clinical Importance:
Because the SI joints bear so much load and stress, they are a common source of low back and pelvic pain. Problems can arise from inflammation (sacroiliitis), arthritis, trauma, or ligament strain. Symptoms often mimic hip or lumbar spine problems, sometimes making diagnosis tricky. Recognizing SI joint dysfunction is important because effective treatments—from physical therapy and injections to minimally invasive procedures—can significantly improve pain and mobility.

What Is Sacroiliac Joint Dysfunction?

Sacroiliac joint dysfunction occurs when one or both joints become irritated, inflamed, or unstable. The result is pain that may be felt in the lower back, buttocks, hips, or groin—and sometimes down the thigh. Because the symptoms overlap with conditions like sciatica or hip arthritis, SI joint pain is often misdiagnosed or overlooked.

At Pain & Vascular Institute in Fox River Grove, IL, we specialize in identifying the SI joint as a source of pain and providing advanced, minimally invasive treatments.

Causes of SI Joint Pain

SI joint dysfunction may develop from a variety of factors, including:

• Trauma or injury – car accidents, sports injuries, or falls directly impacting the pelvis.
• Pregnancy and childbirth – hormonal changes and widening of the pelvis place stress on the joints.
• Arthritis and age-related wear – gradual cartilage breakdown causes inflammation and stiffness.
• Spine surgery – particularly lumbar fusions, which can transfer stress to the SI joints.
• Repetitive stress – heavy lifting, twisting, or uneven movements over time.
• Inflammatory conditions – autoimmune disorders such as ankylosing spondylitis or psoriatic arthritis.

Symptoms of Sacroiliac Joint Dysfunction

Patients may experience:

• Aching or sharp pain in the lower back, buttocks, or hips
  
• Pain radiating into the groin or thigh
  
• Discomfort when standing, sitting, climbing stairs, or rolling in bed
  
• A sense of instability or “shifting” in the pelvis
• Symptoms that mimic sciatica but do not extend below the knee

Diagnosis at Pain & Vascular Institute

Because SI joint pain often mimics other conditions, careful evaluation is essential. Diagnosis may include:

• History and physical exam to look for pain patterns
• Imaging tests (X-ray, MRI, CT) to rule out other causes
• ‘Diagnostic injections — numbing medicine placed into the SI joint to confirm it as the pain source

Treatment Options

At Pain & Vascular Institute, we offer a full spectrum of treatments tailored to your needs, including:

• Physical therapy and activity modification
• Anti-inflammatory medications
• Image-guided steroid injections to reduce inflammation and pain
• Radiofrequency ablation (RFA) to target nerves carrying pain signals from the SI joint
• Minimally invasive SI joint fusion using small implants to stabilize the joint for long-term relief

Our procedures are performed in our state-of-the-art office-based lab (OBL) in Fox River Grove, serving patients from Barrington, Cary, Crystal Lake, Lake Barrington, and McHenry County.