You’ve had a deep ache on one side of your low back or buttock for months, and it flares when you climb stairs or stand up from the couch. Your X-ray and MRI came back normal, and sciatica treatment barely helped.
The sacroiliac (SI) joint may be the source if your doctor hasn’t checked it. Learn how doctors diagnose SI joint pain, which treatments come first and when to see a spine specialist.
What Sacroiliac Joint Pain Is
Your two sacroiliac joints connect the sacrum, the triangular bone at the base of your spine, to the large bone on each side of your pelvis. They carry the load between your upper body and your legs every time you stand, walk or climb.
When one becomes irritated, inflamed or starts moving abnormally, you feel a deep ache in the low back or buttock.
Sacroiliitis is inflammation of the SI joint, often from arthritis or an inflammatory condition. SI joint dysfunction is abnormal movement at the joint, either too much or too little. It can hurt without any inflammation.
You can have SI joint pain without sacroiliitis, so the diagnosis guides what your doctor checks next. Up to 15 to 30 percent of chronic low back pain may come from the SI joint. It’s easy to miss because standard imaging doesn’t show it well.
What Causes Sacroiliac Joint Pain
Many things can trigger SI joint pain, from a single injury to slow wear over time to changes elsewhere in your spine or pelvis.
Age also shifts the likely cause. Younger adults more often have a specific trigger, while older adults more often have wear-and-tear arthritis.
The specific cause shapes how your doctor evaluates you and which treatment comes first, so it’s worth knowing where yours fits.
The common causes include:
- Sports injuries, such as a hard tackle, a fall during skiing or repetitive impact from running that stresses the joint.
- Arthritis in the joint, including wear-and-tear changes.
- Trauma, such as a fall onto the buttocks.
- Pregnancy and childbirth, which loosen the pelvic ligaments.
- Inflammatory conditions such as ankylosing spondylitis.
- Scoliosis.
- A leg length difference that loads one side more than the other
- Prior lumbar fusion, where surgery locks two or more lower-spine vertebrae together. SI joint pain after lumbar fusion runs from about 5.8 percent with one level fused to 22.5 percent with four or more.
Any one of these can set off SI joint pain on its own, and some patients have more than one working together.
At Premier Orthopaedics & Sports Medicine, our pain management specialists work with you to pin down the cause and build a treatment plan that fits your situation.
Knowing which category fits your situation helps your doctor pick the right exam, imaging and first treatment.
Symptoms of SI Joint Pain and How It Differs from Sciatica
SI joint pain has a recognizable pattern. It tends to sit on one side, flare with specific movements and often spread into nearby areas, which is why patients and doctors often confuse it with sciatica or hip pain.
The common symptoms include:
- A deep ache on one side of your low back and buttock that stays put rather than running down the full length of your leg.
- Pain that spreads into the inner thigh or groin on the same side.
- Flare-ups with prolonged sitting or standing, climbing stairs and standing up from a chair.
- Stiffness after a long stretch in one position, such as a long drive or a desk shift.
- A pattern that stays on one side instead of following sciatica’s path down the back of your leg.
Sciatica is another condition, involving nerve pain that travels down the back of the leg. Because both conditions can cause one-sided back and buttock pain that spreads into the leg, SI joint pain is often mistaken for sciatica.
Telling them apart early changes which exam, imaging and first treatment your doctor reaches for. The table below lines up the differences your doctor considers.
| Feature | SI joint pain | Sciatica |
|---|---|---|
| Where pain sits | One side of the low back and buttock, and sometimes the thigh or groin | Through the buttock and down the back of one leg, and sometimes without any back pain |
| Groin pain | Common | Uncommon with disc herniation or stenosis |
| Numbness or weakness | Not typical. If present, your doctor looks for another cause | More often present, since a nerve is involved |
Groin pain is one of the sharper dividing lines. It showed up in 46.5 percent of people with SI joint dysfunction compared with 8.1 percent of those with a lumbar disc herniation and 6.8 percent of those with spinal canal stenosis.
Buttock pain can raise questions about sciatica versus piriformis syndrome, but your doctor may consider groin pain a sign pointing to the joint.
Has Surgery Been Raised for SI Joint Pain?
Most SI joint pain is treated with physical therapy, medication and injections first, and fusion is considered only if those have not worked. If surgery has been raised, a second opinion is a normal step before deciding. Premier’s spine team reviews your prior imaging and records before the visit.
How Doctors Diagnose SI Joint Pain
Your doctor starts with a history and physical exam to narrow the source, since no single test or imaging study confirms SI joint pain. Imaging rules out other causes, and a diagnostic injection then confirms whether the joint is causing the pain.
Why Your X-Ray and MRI Can Look Normal
A normal MRI doesn’t mean the pain isn’t real. Imaging alone isn’t enough to diagnose SI joint pain.
Your doctor will usually start with an X-ray of the pelvis, then order CT or MRI to rule out arthritis, inflammation or a lumbar cause such as a herniated disc or stenosis.
History and Physical Exam
Your doctor will ask when the pain started and whether it followed a fall, a pregnancy or prior spine surgery.
The exam includes provocation tests, which stress the joint in specific positions to see whether your familiar ache shows up.
The five standard provocation tests are:
- FABER (flexion, abduction and external rotation): Your doctor bends and rotates your hip into a figure-four position to load the SI joint and see if it reproduces your pain
- Thigh thrust: With your hip bent, your doctor presses down through your thigh to shear the joint and check for your familiar ache
- Compression: You lie on your side while your doctor presses down on the top of your pelvis to squeeze the SI joints together
- Distraction: You lie on your back while your doctor presses outward on the front of your pelvis to pull the SI joints apart
- Gaenslen: You hang one leg off the exam table while pulling the other knee to your chest, which stresses the SI joint on the dangling side
When three or more of these tests reproduce your pain, the SI joint moves to the top of the list and a diagnostic injection becomes the next step.
The Diagnostic Injection
A diagnostic injection is the clearest way to confirm the SI joint as the pain source when the exam and imaging point toward it but don’t fully settle the question.
Your doctor places local anesthetic directly into the joint under X-ray guidance (called fluoroscopy), and then asks you to rate your pain while the medicine is active.
If most of your pain fades while the anesthetic lasts, that strongly points to the SI joint. If nothing changes, the joint is unlikely to be the cause.
One injection isn’t always reliable, so your doctor may repeat it before settling on a longer-term plan.
Treatment Options for SI Joint Pain
Surgery can be avoided to treat SI joint pain. Treatment starts with physical therapy and medication, moves to steroid injections and radiofrequency ablation if those aren’t enough and considers fusion only as a last step.
Conservative Care First
Exercise and over-the-counter medication are usually where treatment begins:
- Physical therapy focused on pelvic stabilization and stretching, the first-line treatment for most SI joint pain
- Over-the-counter nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen or naproxen to calm inflammation
- Activity changes, such as breaking up long stretches of sitting and avoiding standing on one leg
- Footwear adjustments when a leg length difference is loading one side more than the other
Weight reduction and regular exercise also take load off the joint. If pain hasn’t improved after six to eight weeks of this combination, your doctor usually adds an injection.
Injections and Radiofrequency Ablation
When physical therapy doesn’t bring enough relief, your doctor can add a steroid to the numbing medicine for a therapeutic injection that reduces swelling inside the joint. Relief lasts weeks to months, though pain sometimes returns.
Radiofrequency ablation (RFA) is the next option once diagnostic blocks confirm the joint as the source. Your doctor sends radio waves through a precisely placed needle to heat the small nerves that carry pain signals from the joint, which stops those signals from reaching your brain.
Premier’s pain management treatments include image-guided spine injections and radiofrequency ablation.
SI Joint Fusion When Conservative Care Hasn’t Worked
Your doctor would consider fusion only after physical therapy, medication and injections have failed for more than six months and the diagnostic injection has confirmed the joint as the source.
In carefully selected patients, minimally invasive fusion can improve pain and function compared with continued conservative care, with more adverse events in the first six months and a revision rate of 3.8 percent or less at two years.
What Recovery from SI Joint Pain Looks Like
Recovery usually takes several weeks, and the timeline depends on your treatment.
With focused physical therapy and conservative care, patients have a 72 percent success rate of pain relief. If pain persists and your doctor adds a steroid injection, significant pain reduction has been reported in 62 percent of patients.
Minimally invasive SI joint fusion reached an 81 percent success rate at six months, versus 26 percent for continued nonsurgical care.
You’ll know you’re improving when you can sit through a meal or a car ride without shifting, stairs feel ordinary again and standing up from a chair no longer sends a jolt through your buttock.
If you’re not making progress, our article on back pain treatment NJ options explains the next stage of care.
When SI Joint Pain Calls for a Spine Specialist
See a spine specialist if several weeks of physical therapy and medication haven’t improved your pain. A prior lumbar fusion or a change in the severity or type of your pain also warrants a specialist visit.
If two providers have given you conflicting diagnoses, you can seek a specialist’s evaluation without waiting.
Get Your SI Joint Pain Evaluated at Premier
If months of one-sided back or buttock pain still have no clear explanation, a Premier visit can help you find out whether the SI joint is the source. Call 201-833-9500 or request an appointment at our Englewood office in Northern New Jersey.
Frequently Asked Questions About Sacroiliac Joint Pain in Bergen County
Should I see a rheumatologist for SI joint pain?
Your doctor may refer you to a rheumatologist if inflammation appears to be the main driver. Ankylosing spondylitis and related conditions often start in the SI joints, and your doctor may refer you to a rheumatologist if they suspect inflammation.
Does a sacroiliac belt help?
A belt wraps around the pelvis to limit SI joint movement, and it’s most helpful alongside physical therapy. It can help in pregnancy-related SI joint dysfunction, where the ligaments are already loose. A belt worn directly below the hip bones reduces joint laxity more than one worn lower on the pelvis.
Will my insurance require physical therapy before an SI joint injection?
Some plans ask for documented conservative treatment, usually a course of physical therapy and medication, before they’ll authorize an injection. Requirements vary by plan, and notes from therapy you’ve already completed may count toward them.
Can pregnancy cause SI joint pain that lasts after delivery?
Yes. Pregnancy loosens the pelvic ligaments to prepare for childbirth, and that looseness can persist after delivery. Pelvic stabilization exercises and a belt can help while the ligaments recover. Pain that persists for months after delivery, or that makes it hard to lift your baby or climb stairs, is worth having evaluated.
This article is for general information only and isn’t a substitute for professional medical advice. Talk to your doctor about your specific situation before making treatment decisions.
