Sacroiliac Joint Dysfunction: What It Is, Why It's Misdiagnosed, and How PT Fixes It

Sacroiliac joint dysfunction is one of the most commonly misdiagnosed sources of lower back and hip pain — and one of the most treatable. I'm Dr. Ezra Miller, DPT, and I treat patients with SI joint issues throughout Boca Raton, Delray Beach, and Pompano Beach. In this guide, I'll break down exactly what's happening in the SI joint, why it gets misdiagnosed so often, and what effective physical therapy treatment actually looks like.

What Is the Sacroiliac Joint?

The sacroiliac (SI) joint connects the sacrum — the triangular bone at the base of your spine — to the iliac bones of the pelvis. You have two of them, one on each side of your lower back, positioned just below the dimples you can sometimes see on each side of the lumbar region.

These joints are load-bearing structures. They transfer force from the upper body down through the pelvis and into the legs during walking, running, lifting, and pretty much every upright activity you do. They're held together by some of the strongest ligaments in the body, which is why they're designed for stability rather than large ranges of motion.

Under normal conditions, the SI joints move only a few millimeters. That's by design. When something disrupts that controlled, minimal movement — either too much motion (hypermobility) or too little (hypomobility, often with inflammation) — the result is SI joint dysfunction, and the symptoms can be significant.

Why Is SI Joint Pain So Commonly Misdiagnosed?

The challenge with SI joint dysfunction is that it produces symptoms that closely mimic other common diagnoses. It's estimated that SI joint dysfunction accounts for 15–30% of all chronic lower back pain cases, yet it's often attributed to disc herniation, lumbar facet syndrome, hip pathology, or piriformis syndrome instead.

Here's why the confusion happens:

• Pain referral patterns overlap: SI joint pain typically refers into the buttock, hip, groin, and sometimes down the leg — nearly identical to sciatica and hip impingement.
• MRI and X-rays are unreliable: Standard imaging often shows nothing remarkable in the SI joint, or shows findings that correlate poorly with symptoms. Structural changes in the joint don't always cause pain, and pain doesn't always come with visible structural changes.
• Point of care matters: Most patients with back pain see a general practitioner first, who may be less familiar with SI-specific provocation tests. Without those tests, the SI joint often isn't on the differential at all.
• SI joint pain rarely presents in isolation: It typically coexists with lumbar dysfunction, hip tightness, or pelvic floor issues — making it easy to treat only the secondary findings and miss the primary driver.

Who Gets SI Joint Dysfunction?

SI joint dysfunction shows up across a wide range of patients. In my practice in Boca Raton, I see it most commonly in:

• Pregnant and postpartum women: The hormone relaxin loosens ligaments throughout pregnancy, significantly increasing SI joint mobility. Many women develop SI pain during the third trimester or in the weeks following delivery.
• Runners and cyclists: Repetitive unilateral loading (one side at a time) during running, combined with limited hip extension range of motion, overloads the SI joint over time.
• People who sit for extended periods: Prolonged flexed hip posture compresses the posterior SI ligaments and inhibits the glute and hip stabilizers that protect the joint.
• Anyone who has had a lumbar fusion: Spinal fusion changes load distribution — the SI joint often compensates for lost motion above it, leading to accelerated wear and irritation (sometimes called "adjacent segment disease").
• Post-traumatic cases: Falls, motor vehicle accidents, or even a misstep off a curb can jam the SI joint into a position it doesn't recover from on its own.
• Active older adults: Degenerative changes to the joint surfaces are common after age 50, particularly in those who've had years of asymmetric loading from sport or manual work.

What Does SI Joint Pain Feel Like?

The symptom pattern of SI joint dysfunction is fairly distinctive once you know what to look for:

• Pain localized to one side of the low back, centered around the dimple area (posterior superior iliac spine, or PSIS)
• Referred pain into the buttock, hip, groin, or down the back of the thigh
• Pain that worsens with prolonged sitting, standing from a chair, rolling over in bed, or climbing stairs
• A sensation of the pelvis being "locked," "twisted," or "out of place"
• Difficulty standing on one leg (getting dressed, stepping into pants)
• Pain with weight-bearing on the affected side

What distinguishes SI joint pain from lumbar disc pain in most cases: disc pain tends to be more central or bilateral and typically increases significantly with lumbar flexion (bending forward). SI joint pain is usually unilateral, worse with transitional movements, and doesn't follow a dermatomal (nerve-root) pattern down the leg.

What Causes SI Joint Dysfunction?

At the mechanical level, SI joint dysfunction comes down to altered force transfer through the pelvis. The joint relies on two mechanisms to stay stable during load:

• Form closure: The shape of the joint surfaces — rough, interlocked, like two pieces of a puzzle. This is passive stability.
• Force closure: Muscular tension from the surrounding stabilizers (gluteus maximus, piriformis, biceps femoris, multifidus, and the thoracolumbar fascia) that compress the joint and prevent unwanted motion. This is active stability.

When force closure breaks down — because the stabilizers are weak, inhibited, or poorly coordinated — the joint experiences excessive shear force, strain on the ligaments, and ultimately, pain and inflammation.

Common contributing factors include:

• Weak or inhibited gluteus medius and maximus
• Poor lumbopelvic motor control (the deep stabilizers — multifidus, transverse abdominis — aren't activating before movement)
• Hip flexor tightness pulling the pelvis into anterior tilt
• Leg length discrepancy (true or functional)
• Prior lumbar or hip surgery altering mechanics
• Ligamentous laxity (more common in women, particularly post-pregnancy)

Physical Therapy for SI Joint Dysfunction: What Actually Works

The good news: SI joint dysfunction responds well to targeted physical therapy. The key word is targeted. Generic core exercises, stretching routines, and lumbar stabilization programs that don't specifically address the SI joint and its associated stability system tend to produce limited results.

Here's what an evidence-informed PT approach looks like:

1. Manual Therapy and Joint Mobilization

When the SI joint is hypomobile (restricted, often with accumulated inflammation), manual therapy directed at restoring normal joint mobility can provide rapid and significant pain relief. Techniques include Grade III–IV joint mobilization of the sacroiliac joint, muscle energy techniques (METs) to address pelvic alignment, and soft tissue mobilization of the surrounding hip rotators and posterior ligaments.

In my in-home sessions, I spend significant time here in the early phases of treatment. Patients frequently report immediate reduction in pain following their first manual therapy session — not because I've "fixed" anything permanently, but because I've restored normal arthrokinematics so the joint can move as designed while the stabilization work takes hold.

2. Stabilization Training — The Right Kind

The stabilization work for SI joint dysfunction is more specific than it looks. The goal is to restore force closure — meaning the muscles that compress and protect the SI joint need to be firing in the right sequence, at the right time, with adequate strength. This is not the same as "getting strong abs."

Exercises I use most frequently include:

• Clam shells and side-lying hip abduction (gluteus medius activation)
• Single-leg bridges with cue for posterior pelvic tilt control
• Dead bugs and pallof press variations (lumbopelvic dissociation and anti-rotation)
• Step-ups and lateral step-downs (functional single-leg loading)
• Hip hinge patterns with kettle bell or resistance band loading

The progression matters enormously. Starting with loaded exercises before the stabilizers are properly coordinated is one of the most common reasons people with SI joint pain fail to improve (or worsen) with generic exercise programs.

3. Pelvic Belt / Sacroiliac Orthosis

For patients with significant hypermobility — particularly postpartum women — a properly fitted SI joint belt can be a valuable short-term tool. The belt provides external force closure, reducing joint shear during daily activities while the stabilization program rebuilds internal support. I typically recommend wearing it during high-load activities (walking longer distances, carrying) and weaning off as strength improves.

4. Movement Education

How you move throughout the day matters as much as the formal exercise program. I educate patients on:

• How to stand up from a seated position to reduce SI shear
• Sleeping positions that unload the joint (most patients benefit from a pillow between the knees in side-lying)
• How to modify high-risk movements at work or during sport
• Postural habits that increase SI joint load over time (anterior pelvic tilt, asymmetric standing, crossing legs)

How Long Does It Take to Get Better?

Most patients with SI joint dysfunction who commit to a structured program see significant improvement within 6–10 weeks. That's a meaningful qualifier: significant improvement, not just a good day here and there.

Here's a realistic timeline:

Factors that slow recovery include: incomplete adherence to home exercises, returning to aggravating activities too early, and an underlying cause (such as true leg length discrepancy or ongoing hormonal laxity) that hasn't been addressed.

Why In-Home PT Works Better for SI Joint Issues

SI joint dysfunction has a significant functional component — meaning what happens in a clinic doesn't always translate to real life. In-home physical therapy closes that gap.

When I work with you in your own home, I can:

• Watch how you actually move — getting off your couch, walking your hallway, going up your stairs
• See your sleeping setup and make specific recommendations that reduce overnight load
• Observe your workspace and identify postural contributors to your pain
• Teach you exercises using your own furniture and minimal equipment, so your home program actually gets done
• Monitor how you respond between sessions without a week-long gap between appointments

Most of my SI joint patients see me 2 times per week in the early phases. That frequency — impossible to maintain at a typical clinic with commute times and scheduling friction — makes a measurable difference in how quickly they progress.

SI Joint Pain FAQs

Can the SI joint cause leg pain?

Yes. The SI joint refers pain into the buttock, hip, and back of the thigh in most cases. It can occasionally produce symptoms as far as the knee, though true neurological symptoms (weakness, numbness, tingling in a dermatomal pattern) point more toward lumbar disc involvement. A good clinical evaluation can differentiate these.

Is walking good for SI joint dysfunction?

Generally yes, with caveats. Low-volume walking on flat surfaces is usually well-tolerated and beneficial. Long walks, inclines, and walking on uneven terrain can aggravate an irritated SI joint. I typically give patients a specific walking prescription based on their current tolerance and increase it progressively.

Can SI joint dysfunction come back?

Yes — particularly if the root cause (poor stabilization, ligamentous laxity, hip mobility deficits) isn't fully addressed. That's why the program doesn't end when pain ends. I push patients through a full return-to-function phase and leave them with a maintenance routine they can do independently to prevent recurrence.

Does a chiropractor help SI joint pain?

Many patients with SI joint pain find short-term relief from chiropractic manipulation. The mechanism is similar to manual therapy — restoring joint mobility and reducing pain. The limitation is that manipulation alone doesn't address the force closure deficits that caused the problem. A combined approach — manual therapy for immediate relief, stabilization training for lasting correction — tends to produce the best long-term outcomes.

What should I avoid with SI joint pain?

In the acute phase: prolonged sitting on soft surfaces, asymmetric loading (crossing legs, standing with weight on one leg), high-impact activities, and heavy single-leg loading. Once stable: most activities can be reintroduced progressively with proper technique.