Is Your Low Back Pain Really Coming From Your SI Joint?
Understanding the link between the sacroiliac joint and low back pain, and how physical therapy can help
If you’ve been told you have “low back pain” but the ache sits low and to one side, near the dimples above your buttocks, your sacroiliac (SI) joint may be part of the story. It’s one of the most commonly overlooked sources of low back pain.
What is the SI joint?
You have two sacroiliac joints, where the base of your spine (the sacrum) meets your pelvis. Together they transfer load between your upper body and your legs. The SI joint is the largest axial joint in the body, and it’s held stable by ligaments and the muscles around it, including the gluteals and piriformis.
When the joint moves too much, too little, or becomes irritated, it can cause pain in the low back or buttock. That pain can also spread to the groin, hip, or leg. Some people notice tingling or numbness, or feel the pain shift from dull to sharp.
What the research says about SI pain and low back pain
Low back pain is extremely common. Roughly 65 to 80% of adults will experience it at some point, and it is a leading cause of disability worldwide. How much of it comes from the SI joint is less settled:
- Prevalence estimates vary. Reviews place the SI joint as the primary pain source in about 10 to 30% of people with low back pain, depending on the study and how it was diagnosed.
- It may be under-recognized. A 2021 chart review in the Spartan Medical Research Journal looked at 84 adults treated with osteopathic manipulation for low back pain at one primary care clinic. SI dysfunction was identified in about 61% of them, and women were more likely to be affected. That is well above earlier estimates. The authors were careful to note that the study was small and retrospective, and that documentation wasn’t standardized. But they suggest the SI joint may be missed when providers focus only on the lumbar spine.
- Diagnosis is hands-on. X-rays and lab tests can’t confirm SI dysfunction. Physical therapists use a cluster of provocation tests, such as the distraction, thigh thrust, and Gaenslen tests, along with movement and alignment assessment. In one published case report, a patient with two years of “non-specific” low back pain tested positive on three of five SI tests. That finding redirected her treatment plan.
Because SI pain overlaps with lumbar spine and hip problems, a thorough evaluation matters. A good exam can also save you from unnecessary imaging and years of treatment aimed at the wrong target.
How physical therapy helps
A 2025 systematic review and meta-analysis in the Journal of Bodywork and Movement Therapies pooled 24 randomized trials of physical therapy for SI joint dysfunction. It concluded that physical therapy reduces pain and improves function, and that a combined approach may work best. Here is what a well-rounded plan usually includes.
Manual therapy and mobilization. Hands-on techniques, including joint mobilization and muscle energy techniques (MET), aim to restore comfortable movement at the joint and calm surrounding muscle guarding. In the meta-analysis, both MET and mobilization significantly reduced pain. A small case series of two patients also reported less pain and better function after ultrasound plus Kaltenborn ventral glide and lumbopelvic rotation mobilization. That is very early evidence, but it fits the broader picture. Manual therapy is often a good way to get moving again, but it works best as one part of the plan.
Motor control and stabilization. Current approaches start with waking up the deep stabilizers of the lumbopelvic region (the transversus abdominis, multifidus, and pelvic floor). From there, we progress to endurance and task-specific loading, such as lifting, walking, and getting in and out of a car. This is where lasting results tend to come from. In the meta-analysis, exercise was the only intervention that significantly improved disability scores, and it also reduced pain.
Supportive modalities. Kinesio taping, pelvic belts, ultrasound, and TENS can ease short-term pain and make it easier to move. The evidence for them is more mixed. In the meta-analysis, taping didn’t show a significant benefit, and in one case report a pelvic belt gave only brief relief. We use these tools selectively, as a bridge to active care rather than as the whole treatment.
Pain science education. Understanding why your back hurts, and why hurting doesn’t always mean harming, lowers fear and helps you keep moving. Reviews suggest that pairing education and attention to stress, sleep, and confidence with exercise leads to better medium-term outcomes than exercise alone. It also matters for the long run. Most acute low back pain settles within four to six weeks, but a small share becomes chronic, and early, active care lowers that risk.
3 gentle exercises for acute SI and low back pain
These are meant to calm things down, not to push through pain. Move slowly, stay in a comfortable range, and stop any exercise that sharply increases your pain or sends symptoms down your leg.
When to skip home care and call us or your doctor: new numbness or weakness in the legs, changes in bladder or bowel control, numbness in the groin or saddle area, fever, pain after a significant fall or accident, or pain that isn’t easing after a couple of weeks.
Ready for a clear answer?
If your low back or pelvic pain keeps coming back, or hasn’t improved on its own, a hands-on evaluation can sort out whether your SI joint, lumbar spine, hip, or pelvic floor is driving it. Our physical therapists build an individualized plan combining manual therapy, targeted stabilization, and education so you can get back to what you love.
References
- Wieczorek A, et al. “A Closer Look into the Association between the Sacroiliac Joint and Low Back Pain.” Spartan Medical Research Journal, 2021.
- Erawan T, et al. “Integrative Physiotherapy Approaches for Sacroiliac Joint Dysfunction: Efficacy of Ultrasound, Ventral Glide Mobilization, and Lumbopelvic Rotation Mobilization.” J Pharm Bioallied Sci, 2025 (two-patient case study).
- Jangra P, et al. “A systematic review and meta-analysis of randomized controlled trials on the effect of various therapeutic interventions on sacroiliac joint dysfunction.” J Bodyw Mov Ther, 2025.
- Remer S. “Chronic Low Back Pain with Possible SI Involvement and Weak Abdominals: A Case Study.” University of North Dakota, 2021.
