SI Joint Pain: Causes, Symptoms, and Effective Treatment

The Joint Nobody Talks About

You have low back pain. Maybe it radiates into your buttock or thigh. You've seen doctors, tried stretches, maybe even had imaging. But nothing quite explains it.

Here's a possibility often overlooked: your sacroiliac joint—the SI joint.

SI joint dysfunction accounts for 15-30% of chronic low back pain cases. Yet it's frequently misdiagnosed as disc problems, sciatica, or generic "low back pain." Understanding the SI joint can be the key to finally finding relief.

What Is the SI Joint?

The sacroiliac joints are where your spine meets your pelvis. You have two of them—one on each side of your sacrum (the triangular bone at the base of your spine).

These joints don't move much—only a few degrees. But they transfer enormous forces between your upper body and legs. Every step you take, every time you sit or stand, your SI joints are working.

Key point: The SI joint is designed for stability, not mobility. Problems arise when it becomes either too stiff or too loose.

SI Joint Pain Symptoms

Location:

Pattern:

Classic sign: Point to your pain with one finger. If you point to the area just below your waist, off to one side (over the SI joint), that's suggestive.

SI Joint vs Other Causes

SI Joint Pain:

Disc/Sciatica:

Facet Joint Pain:

Hip Pain:

In reality, these conditions often coexist. Getting the right diagnosis matters for effective treatment.

Causes of SI Joint Dysfunction

1. Hypermobility (Too Loose)

The joint moves more than it should, causing instability.

Risk factors:

2. Hypomobility (Too Stiff)

The joint doesn't move enough, creating abnormal stress.

Risk factors:

3. Inflammation

Inflammatory conditions can affect the SI joint.

Examples:

4. Trauma

Fall onto buttock, car accident, or sports impact.

5. Muscle Imbalances

Weak glutes, tight hip flexors, and core dysfunction alter forces through the SI joint.

Self-Assessment

Single-Leg Stance Test

Stand on one leg for 30 seconds. Pain in the SI joint area on the standing side = possible dysfunction.

FABER Test

Lie on back. Place ankle of affected side on opposite knee (figure 4 position). Let knee fall toward floor. Pain in SI joint area = positive.

Posterior Pelvic Pain Provocation Test

Lie on back, hip flexed to 90 degrees. Partner pushes down through knee toward table. Pain in SI joint = positive.

Note: No single test is definitive. Multiple positive tests increase likelihood.

The Treatment Approach

For Hypermobility/Instability

1. Stabilization Exercises

The goal is to strengthen muscles that support the SI joint.

Dead Bugs

Lie on back, arms up, knees bent 90°. Lower opposite arm and leg while keeping lower back pressed into floor.

Bird Dogs

Hands and knees. Extend opposite arm and leg without rotating spine. Hold 5 seconds.

Pallof Press

Band attached to side, hold at chest. Press arms forward, resisting rotation.

Side Plank

Build toward 30-second holds, ensuring hips don't sag or pike.

Glute Bridges

Focus on level hips and controlled movement.

2. SI Belt

A sacroiliac belt worn around the pelvis can provide temporary stability. Useful during acute flares or high-demand activities. Not a long-term solution—strengthening is.

3. Avoid Aggravating Positions

For Hypomobility/Stiffness

1. Mobility Exercises

Knee-to-Chest

Lie on back, pull one knee toward chest. Gentle stretch through SI area.

Supine Twist

Lie on back, arms out. Cross one leg over body, let it fall toward floor. Keep shoulders down.

Thread the Needle

Hands and knees. Reach one arm under body, rotating thorax. Open up toward ceiling.

Hip Flexor Stretch

Half-kneeling, squeeze glute, shift forward. Opens up the front of the pelvis.

2. Muscle Energy Techniques

These can help "reset" the joint position:

Prone SI Joint Reset

Lie face down, one knee bent to 90°. Gently press that knee into the table while breathing. Hold 5 seconds, relax. Repeat 5 times per side.

For Both Types

1. Glute Strengthening

Strong glutes stabilize the pelvis and reduce SI joint stress.

Single-Leg Glute Bridge

Side-Lying Hip Abduction

Clamshells

2. Hip Flexibility

Tight hips alter pelvic mechanics.

Address hip flexors, piriformis, and adductors as needed.

3. Core Stability

The core and SI joint work together. See core stability article for full protocol.

Activity Modifications

During Flares:

For Ongoing Management:

Timeline for Improvement

Acute SI flare: 1-2 weeks with proper management

Chronic SI dysfunction: 6-12 weeks for significant improvement

Key insight: SI joint issues often recur. Ongoing maintenance is necessary—this isn't a "fix it once and forget it" situation.

When to See a Professional

Get evaluated if:

Who to see:

Treatment options from professionals:

The Bottom Line

SI joint pain is common, underdiagnosed, and very treatable:

1. Location is key — Pain over the SI joint area, one-sided

2. Know your type — Unstable vs stiff requires different approaches

3. Stabilize the system — Core and glutes are essential

4. Stay consistent — This takes weeks to months, not days

5. Maintain long-term — Recurrence is common without ongoing work

Your SI joint is a workhorse—give it the support it needs.

SI joint pain limiting your movement? The Foundational Rehab app includes pelvic stability programs—targeted exercises for lasting relief.