You have lower back pain. Your doctor orders an MRI. It comes back mostly normal. And yet the pain keeps coming back. If that sounds familiar, there is a good chance no one has checked your sacroiliac joint.
The sacroiliac (SI) joint sits where your lower back meets your pelvis. Research published in EClinicalMedicine found the SI joint may account for up to 30% of persistent lower back pain cases [1] — but it often goes undetected because imaging rarely shows the problem. It is one of the most overlooked and undertreated sources of back pain.
What Is the SI Joint and Where Does It Hurt?
The SI joint connects the sacrum — the triangular bone at the base of your spine — to the ilium, the large bone on each side of your pelvis. Its job is to absorb shock between your upper body and your legs when you walk, run, or climb stairs.
Most people feel SI joint pain just below the beltline, usually on one side. It can spread into the buttock, the back of the thigh, or the groin. The pain often gets worse when you stand up from sitting, roll over in bed, or shift your weight to one leg. People usually describe a deep ache that sharpens with certain movements.
Why Does SI Joint Pain Get Missed So Often?
SI joint pain overlaps with sciatica, herniated discs, and hip problems — which is why it often gets bypassed. Many people spend months being treated for other conditions without improvement, simply because the SI joint was never examined.
Standard MRI is not a reliable tool here. A 2023 systematic review in EClinicalMedicine found that a combination of physical examination tests, not imaging, is the most reliable method for identifying SI joint pain [1]. A trained examiner uses targeted pressure maneuvers to determine whether the joint is the source. If you’ve been told your imaging looks fine but something still feels off, this distinction matters. Herniated disc vs. bulging disc: What’s the difference?
What Causes SI Joint Problems?
Pregnancy is a major trigger — hormones that loosen pelvic ligaments can allow too much motion in the joint. A fall, a car accident, or a leg length difference can load one side asymmetrically over time. Repetitive activities like distance running and cycling add cumulative stress.
Weakness in the core and hip muscles is a common contributing factor. When those muscles aren’t stabilizing the pelvis properly, the SI joint absorbs more force than it was built for. This is one reason SI joint problems frequently show up in people who sit for long hours. See also: Why sitting all day is hurting your back.
How Is SI Joint Pain Treated?
Conservative care works for most people. A 2024 clinical trial in Frontiers in Physiology found that combining manual joint mobilization with core stability exercises reduced pain and disability significantly better than exercises alone, with improved lumbopelvic stability and range of motion throughout [3].
A 2024 meta-analysis in the Journal of Manual and Manipulative Therapy reviewed 16 randomized controlled trials involving 421 adults and found that manual therapy — including chiropractic manipulation and mobilization — had a statistically significant moderate effect on reducing disability in people with SI joint pain [2].
A 2025 review in the European Journal of Orthopaedic Surgery and Traumatology, covering 38 studies and 2,666 patients, confirmed that conservative care and physical therapy are the standard first-line treatment before considering injections or more invasive procedures [4].
For people with unexplained lower back pain that has never been fully resolved, an SI joint evaluation is often the missing step. Chiropractors, physical therapists, and orthopedic specialists trained in SI joint assessment can help identify whether this is the source. Learn more about back and neck pain conditions we treat.
The Bottom Line
The SI joint accounts for a meaningful share of lower back pain cases, and it is frequently mistaken for other conditions. If you have had nagging pain in the lower back or buttock without a clear explanation, an SI joint evaluation is worth pursuing.
Conservative treatment works well once the problem is correctly identified. Targeted exercise, manual therapy, and movement corrections can make a real difference — often without needing medication or surgery.
Sources & Further Reading
- Han CS, Hancock MJ, Sharma S, et al. Low back pain of disc, sacroiliac joint, or facet joint origin: a diagnostic accuracy systematic review. EClinicalMedicine. 2023;59:101960. doi:10.1016/j.eclinm.2023.101960
- Trager RJ, Baumann AN, Rogers H, et al. Efficacy of manual therapy for sacroiliac joint pain syndrome: a systematic review and meta-analysis. J Man Manip Ther. 2024;32(6):561–572. doi:10.1080/10669817.2024.2316420
- Tantawy SA, et al. The effects of Core Stability Exercises and Mulligan’s mobilization with movement techniques on sacroiliac joint dysfunction. Front Physiol. 2024. doi:10.3389/fphys.2024.1337754
- Migliorini F, Lucenti L, Bardazzi T, et al. Management of sacroiliac joint pain: current concepts. Eur J Orthop Surg Traumatol. 2025;35:208. doi:10.1007/s00590-025-04308-2
