SI Joint Pain (Sacroiliac Joint Dysfunction)

The sacroiliac joints connect the base of the spine (the sacrum) to the pelvis on each side. They are built for stability, not motion: strong ligaments hold them together and they move only a few degrees. Their job is to transfer load between the trunk and the legs every time you stand, step, or lift.

That last point matters, because a lot of what gets said about the SI joint is not accurate. The pelvis does not routinely "go out" or "rotate" and need to be put back. Research measuring actual SI joint movement finds it small, and studies of clinicians trying to feel pelvic position find they largely cannot agree with each other. If someone diagnosed your SI joint by feeling for an asymmetry, that is not a reliable basis for the diagnosis or the treatment.

What is real is that the joint and the ligaments around it can become irritated and painful, and that this accounts for a meaningful share of chronic low back pain, commonly estimated somewhere between one in six and one in three cases. Diagnosing it properly is the first step.

Imaging does not diagnose SI joint pain; X-rays and MRI of the joint look similar in people with and without symptoms. The most reliable clinical approach is a cluster of provocation tests, where the joint is stressed in several directions and the test is positive if it reproduces your pain. When three or more of these tests are positive, the joint is likely the source; when they are all negative, it almost certainly is not.

Just as important is ruling out the neighbors. The lumbar spine and the hip both refer pain to the same low, one-sided spot. A proper exam screens both before landing on the SI joint, because treating the wrong structure is how people end up with months of adjustments and no change.

Runners and lifters who load one side more than the other. People in the months around pregnancy, when hormonal changes make the ligaments more lax and the load on the pelvis shifts week to week. Anyone who has had a fall onto the buttock or a hard step off a curb. And people with stiff hips or a stiff lumbar spine, where the pelvis ends up absorbing motion the joints on either side of it should be handling.

The story first: where exactly it hurts, what brings it on, whether there was an injury or a pregnancy, what has been tried. Then the exam: lumbar spine and hip screening, the SI provocation cluster, hip and trunk strength, and how you move through standing on one leg, stepping up, and a hinge. I want to see where load goes when the pelvis has to hold steady.

You leave knowing whether the SI joint is likely the source, what to change immediately to reduce flares, and the first strength exercises. For pregnancy-related pain, we also talk through supports, positioning for sleep, and how to handle lifting and carrying.

The evidence for SI joint pain favors exercise and education over passive treatment. Hands-on work can reduce guarding and make movement more comfortable in the short term, and I use it, but it is the on-ramp, not the plan.

The plan is strength and control. The glutes, hip rotators, and deep trunk muscles are what stabilize the pelvis under load; when they are weak or slow, the ligaments take the strain. So we build them: bridges and hip thrusts, side-lying and standing hip work, anti-rotation trunk work, and then single-leg control, because most SI pain flares in single-leg positions. Load and difficulty progress as you tolerate them.

Then we address the asymmetry. If you run, we look at stride and cadence. If you lift, we look at how you set up and whether one side is doing more. If you carry a child on one hip all day, we talk about switching sides and building the strength to do it comfortably.

A sacroiliac belt can be genuinely helpful for pregnancy-related pelvic girdle pain and in the early, irritable phase for others; it gives the joint some external compression while strength builds. It is a bridge, not a destination.

For pain that does not settle with a proper course of rehab, a diagnostic injection into the joint can confirm the source and provide relief, and radiofrequency procedures exist for stubborn cases. Those are conversations for after rehab, not instead of it. What I would skip: repeated manipulations to "realign" the pelvis. They may feel good for a day, but the evidence does not support them as a treatment, and the joint was not out of place to begin with.