Sacroiliac Joint Pain: Causes, Symptoms & Treatment (Bangbae)

Deep pain in one buttock may come from the sacroiliac joint rather than the lower back, and most cases improve with nonsurgical treatment that restores pelvic stability.

Your lower back hurts, but is it a back problem or a pelvic problem? Sacroiliac joint pain can feel similar to a herniated disc and is often confused with it, so you need to pin down where the pain is coming from before a treatment plan can take shape. Here we answer frequently asked questions about the sacroiliac joint, which can be a hidden cause of low back and pelvic pain.

Where Is the Sacroiliac Joint?

The sacroiliac joint is where the sacrum, at the very bottom of the spine, meets the ilium on each side. There is one on each side, between the lower back and the upper buttocks. Although it moves only a tiny amount, it is the passageway that transfers the weight of the upper body to the lower body, making it a key joint for absorbing impact and maintaining balance at the body's center.

Why Is It Called a "Semi-Joint"?

Unlike other joints, the sacroiliac joint prioritizes stability. The anterior and posterior sacroiliac ligaments, the sacrospinous ligament, and the sacrotuberous ligament hold the joint firmly in place, and movement is limited to tiny rotations and glides of about 2 to 4 degrees. That is why it is called a semi-joint that barely moves. Transferring body weight from the spine through the pelvis to the legs, absorbing impact, and maintaining stability during walking are all jobs of the sacroiliac joint.

How Is Sacroiliac Joint Pain Confused with a Herniated Disc?

When something goes wrong with the sacroiliac joint, it causes pain that resembles a herniated disc. The most important clue is pain on one side of the buttocks.

What to look for	What's common with sacroiliac joint pain
Location of pain	Deep in one buttock, lower part of the back
When it gets worse	When sitting for a long time, when getting up from a seat
When walking	Discomfort while walking
Why it's confused	Pain spreading to the leg makes it easy to mistake for a disc problem

What Causes It?

Sacroiliac joint pain has more than one cause.

Repetitive stress: Sitting for long periods, habitually shifting weight to one side, poor posture
Trauma: Falls, car accidents, or a hard blow to the buttocks
Pregnancy and childbirth: The hormone relaxin loosens ligaments and makes the pelvis unstable
Exercise and overuse: Asymmetrical movements such as running, hiking, and golf
Muscle imbalance: Weak gluteal muscles and insufficient core strength

How Is It Treated?

Most sacroiliac joint pain improves without surgery. Treatment centers on exercises that restore pelvic stability.

Exercise therapy: Core stabilization exercises such as planks and bridges, and glute-strengthening exercises such as hip abduction and clamshells
Physical therapy: Heat therapy, electrical stimulation, and therapeutic ultrasound to reduce pain and improve blood flow
Manual therapy: A process of correcting pelvic alignment and restoring joint mobility and muscle balance
Injection therapy: Sacroiliac joint injections (steroid) when pain is severe
Lifestyle changes: Not shifting weight to one side, maintaining good posture, not sitting for long periods

In Summary

The sacroiliac joint is small, but it is responsible for the body's balance and load transfer. If you keep having unexplained pain in one buttock, don't assume it's purely a lower back problem; it's worth considering the sacroiliac joint as well. At Ssukssuk Rehabilitation Medicine Clinic in Bangbae, we identify the cause of low back pain, then build treatment around exercise therapy, adding manual therapy and injection therapy as your condition requires.

Last reviewed: 2026-10-07 This article provides general medical information. Individual diagnosis and treatment plans are determined through an in-person consultation.