Sacroiliac (SI) joint pain

The sacroiliac joints connect the sacrum to the pelvis. When they are irritated, people often feel buttock pain that can be mistaken for sciatica or hip trouble.

What it feels like

Pain is usually centered in one buttock or the dimple region of the low back and pelvis, sometimes referring into the posterior thigh.

Transitions (sit to stand, getting out of a car, climbing stairs) and prolonged sitting can flare symptoms.

True neurologic foot drop or a crisp dermatomal handoff into the foot is less typical than with nerve-root sciatica.

What is going on

The SI joint can become painful after pregnancy-related change, trauma, gait imbalance, lumbar fusion adjacent stress, or inflammatory conditions.

It is a real joint with a capsule and innervation, which is why diagnostic injections are sometimes used when the exam is suggestive.

Imaging alone rarely proves SI pain. Provocative exam clusters and response to targeted care matter more.

How we evaluate

We use a cluster of SI provocation tests, neurologic screening, and hip exam to narrow the differential.

Lumbar radiculopathy and facet patterns are considered in parallel so we do not chase the wrong generator.

When needed, a diagnostic SI joint injection under image guidance can support the diagnosis.

What we may offer

Pelvic mechanics, strength balance, and physical therapy are common foundations.

Image-guided SI joint injections may be used diagnostically and for selected therapeutic windows.

If lumbar nerve-root pain is actually dominant, we pivot to disc or stenosis pathways and may discuss epidural steroid injections.

How do you tell SI pain from sciatica?

SI pain is more buttock-centered with less distal nerve-root travel. Sciatica more often follows a clear leg dermatome with nerve findings.

Can SI joint pain refer into the leg?

Yes, often into the buttock and thigh. Past the knee is less classic and makes us look harder for a lumbar root source.

Do I need a fusion for SI pain?

Most people do not. We start with diagnosis, rehab, and injections when appropriate before any surgical conversation.

Is this related to my low back MRI?

Sometimes lumbar findings coexist. We still have to decide which structure is generating the pain you feel day to day.