Sacroiliac Joint Pain and Why It Feels Like Back Pain

You reach for something on a low shelf, feel a jab low on one side of your back, and assume it is your usual back trouble again. But the spot is a little lower than normal, closer to your beltline, and it seems to travel into your buttock or the back of your thigh. This pattern is a classic sign of sacroiliac joint pain, a common source of low back trouble that gets mistaken for a disc or muscle problem more often than you would think.

What the sacroiliac joint actually does#

You have two sacroiliac joints, often shortened to SI joints, one on each side of your lower spine. They sit where your sacrum, the triangular bone at the base of your spine, meets your ilium, the wide upper part of your pelvis. Picture your spine as a tower and your pelvis as its foundation. The SI joints are the connection points where the tower meets the base.

These joints are not built for big, sweeping motion the way your hip or shoulder is. They shift only a few millimeters and rotate just a degree or two under normal conditions. Their job is stability, not range of motion. Thick ligaments wrap around them and hold everything snug, letting the joint absorb shock and transfer force between your upper body and your legs every time you walk, climb stairs, or stand up from a chair.

Because the movement is so small, the SI joint rarely gets much attention until something throws it off. When it does act up, according to OrthoInfo from the American Academy of Orthopaedic Surgeons, it is a genuinely common cause of low back and buttock pain, though it often goes unrecognized because its symptoms overlap so heavily with other back problems.

Why it feels like ordinary back pain#

The SI joints sit close to your lower spine, hip joints, and the nerves that run down your legs. That crowded neighborhood is exactly why SI pain gets mistaken for something else.

Pain from this joint typically shows up:

• Low on one side of your back, near a small dimple above the buttock
• Across the buttock itself
• Down the back of the thigh, sometimes as far as the knee
• Occasionally in the groin or front of the hip

That spreading pattern looks a lot like sciatica, which comes from irritation of the sciatic nerve rather than the joint itself. If you want to understand that overlap better, our guide to sciatica explained breaks down how nerve pain differs from joint pain, even though both can send an ache down your leg. The Cleveland Clinic notes that SI joint pain is frequently confused with a herniated disc or hip arthritis for exactly this reason. The location is close enough, and the referred pain travels far enough, that the joint quietly hides behind other diagnoses.

Certain movements tend to give it away. People with SI joint trouble often notice more pain when standing up from sitting, climbing stairs, rolling over in bed, or standing on one leg to put on pants. Sitting for a long stretch on one side, or driving with one leg angled awkwardly, can also flare it.

What sets off SI joint pain#

The SI joint can become painful for a few different reasons, and they generally fall into three buckets: too much motion, too little motion, or inflammation in the joint itself.

Pregnancy. This is one of the most common triggers. During pregnancy, your body releases a hormone called relaxin that loosens ligaments to help prepare the pelvis for childbirth. That same loosening can make the SI joints move more than usual, which leads to instability and pain, especially in the later months as the added weight and shifted center of gravity load the pelvis differently. If you are pregnant and dealing with this kind of pain, our article on chiropractic care during pregnancy covers safe, gentle options worth discussing with your provider.

Uneven movement and repeated stress. A leg length difference, a strong preference for standing on one leg, running with an uneven gait, or a job that involves a lot of twisting and lifting can all load one SI joint more than the other over time. Sports that involve pivoting or sudden stops, like soccer or tennis, can trigger it too.

A fall or sudden impact. Landing hard on one side, a car accident, or a misstep off a curb can jolt the joint and irritate the ligaments around it.

Arthritis. Like any joint, the SI joint can develop wear and tear arthritis over the years, and inflammatory forms of arthritis, such as ankylosing spondylitis, can target this joint specifically.

Post surgical changes. People who have had spinal fusion surgery sometimes develop SI joint pain afterward, since the joints below a fusion take on extra motion to compensate.

How it gets identified#

Because imaging alone often cannot confirm SI joint pain, and because the pattern mimics other back problems, a careful physical exam matters a great deal here. A clinician typically asks about where the pain sits, what movements bring it on, and whether it started after an injury, a pregnancy, or gradually with no clear cause.

From there, they usually perform a handful of specific movement and pressure tests, pressing on the joint from different angles or moving your hip and leg in particular ways to see if that reproduces your familiar pain. No single test proves it on its own, but as research reviewed by the National Institutes of Health explains, a cluster of several positive tests together makes SI joint dysfunction a much more likely explanation. Occasionally, an injection of numbing medication directly into the joint under imaging guidance is used to confirm the source, since relief from that injection points squarely at the joint.

Conservative care options#

The encouraging news is that most SI joint pain responds well to conservative, non surgical care, and surgery is considered only after other options have been tried and have not helped.

Rest from aggravating movements, not total rest. Cutting back on the specific activities that flare your pain, like standing on one leg or twisting under load, gives the joint a chance to calm down. Staying completely still for long stretches tends to make things stiffer, not better, so gentle daily movement is usually encouraged.

Ice or heat. Ice can ease acute flares, while heat often helps loosen the surrounding muscles when things feel tight and chronic.

Targeted exercise. Physical therapists and chiropractors often focus on strengthening the muscles that support pelvic stability, particularly the deep core, glutes, and hip muscles. A stronger support system around the joint means less strain lands directly on it.

A support belt. Some people with pregnancy related SI pain or joint instability find relief from a sacroiliac support belt, a simple band worn snug around the pelvis that helps compress and stabilize the joint during daily activity.

Manual therapy and chiropractic care. Many people report meaningful relief from hands on techniques aimed at the SI joint, including gentle adjustments, mobilization, and soft tissue work on the surrounding muscles. If the joint is too mobile, treatment often focuses on stability and strength. If it feels locked or stiff, gentle mobilization may help restore normal motion. The Cleveland Clinic lists physical therapy and manual therapy among standard first line approaches, alongside medication and, for stubborn cases, injections.

Anti inflammatory medication. Over the counter options can take the edge off pain and inflammation while you work on the underlying movement patterns, though this is a question for your own doctor or pharmacist given your health history.

For persistent cases, a doctor may suggest a corticosteroid injection directly into the joint, which can calm inflammation for weeks or months and create a window where exercise and therapy are easier to tolerate. Surgery, usually a fusion of the joint, is reserved for cases where thorough conservative care over a meaningful stretch of time has not brought relief.

When to see someone#

A little soreness after an awkward twist or a long day on your feet is common and usually settles with rest. But it is worth getting checked if your pain lasts more than a couple of weeks, keeps coming back, limits your ability to walk or climb stairs, or spreads down your leg in a way that concerns you. Fever along with back pain, or numbness and weakness that is getting worse, needs prompt medical attention, since those can signal something beyond a simple joint issue.

If your low back pain has never fully made sense, and it seems to sit lower and further to one side than typical back pain, mentioning the sacroiliac joint by name to your clinician can help point the exam in the right direction. It is a small, easily overlooked joint, but recognizing it as the source is often the first real step toward relief.

Common questions#

How do I know if my pain is coming from my SI joint and not my back? It is hard to tell on your own since the pain often sits low on one side near a dimple in the pelvis and can spread to the hip, groin, or thigh. A clinician can often confirm it using specific movement and pressure tests during an exam.

Can chiropractic care help sacroiliac joint pain? Many people report relief from gentle adjustments, mobilization, and targeted exercise for SI joint pain. Research on manual therapy for this joint is still limited compared to low back pain in general, so results vary from person to person.

Does sacroiliac joint pain go away on its own? Mild irritation often eases with rest, movement changes, and time. Pain that lingers for more than a few weeks, or that keeps returning, is worth having evaluated so you can get a plan suited to the cause.