The Role of the SI Joint in Hip and Low-Back Pain

 By George Russell, February 1, 2024

The hip and the lumbar spine are intimately connected, and I always work on them both when a client has trouble with either hip or low-back pain. But there’s another joint in between the two—the sacroiliac joint (SI)—that can play an important part in both dysfunction and helping a client get relief.

Here, we’ll discuss why considering if a client’s SI joint is involved in their hip or low-back pain is important, as well as strategies massage therapists can use to help their clients improve stability and mobility, as well as relieve pain.

A Broader Perspective: Making the SI Joint Connection

Before the 20th century, anatomists assumed that the sacrum and pelvis operated as a single bone. Now we know that the SI joint does indeed move and its dysfunctions create significant problems, not only pain but also alignment.

When thinking through how I can help a client experiencing pain related to the SI joint—as well how I can address pain in the whole pelvic region—I like to think of the ilia as the “Mousketeer Ears” of the pelvis and, further, a part of a person’s leg. Think of it this way: I picture the sacrum at the end of the spine as a fishtail and the ilia as the start of the client’s leg, all the way up to the iliac crest and anterior superior iliac spine.

You might be wondering: How is that helpful?

Considering the pelvic region more broadly and thinking of the SI joint as the link between the leg and the spine can give us clarity around both what might be causing a client’s issues as well as how we can bring them some relief.

Related: Relieving Sciatica

Massage and the SI Joint: Relieving Hip and Low-Back Pain

To better understand the role SI joint dysfunction plays in pain, as well as how massage therapy can help reduce symptoms, let’s review some basic structures in the pelvic region and how they function, starting with the ilium.

Consider the ilium the scapula of your leg. Like the shoulder blade, the ilium’s main movement is to turn around its own center like a wheel, allowing your leg to rise and fall.

In the shoulder, this motion is called the “upward and downward rotation of the shoulder blade.” When talking about the ilium, we refer to this motion as the “flexion and extension of the SI joint.”

Flexion occurs when one ilium spins toward a tucked pelvis, helping you lift your knee higher.

Extension is when the ilium spins the other way and arches, causing the leg and torso to lock together so a person can balance on one leg.

Now, it’s true that the the SI joint doesn’t move much, but its ability and freedom to move are important. If the hip and SI joint aren’t flexing well, which is common in clients with hip and low-back issues, tucking the whole pelvis to get the knee into the air becomes necessary, which puts strain on the low back and can lead to lumbar spine problems. That’s why keeping the hip—and the SI joint—working well is so critical.

Amazing, right?

So what does that mean for massage therapists? You can help your clients so much by addressing SI joint dysfunction during a massage session.

SI joint motion is often discussed as only passive because, with the exception of the pelvic floor muscles, there are no muscles that pass directly from the pelvis to the sacrum.

But that’s not really true.

The stabilizing pelvic floor and several hip joint muscles, for example the glutes and piriformis, influence the motion of the sacrum. When they are asymmetrical, the pelvis twists and wreaks havoc on a person’s gait and stability, among other things.

But of all the muscles that impact the SI joint, the most influential is the iliacus. Its fibers attach to the inner groin, angle across the fulcrum of the pubic bone, and connect via powerful fibers to the whole inside of the ilium.

When your torso stays still and you stand on one leg, the iliacus flexes and externally rotates your thigh to create an action similar to if you were to step one leg onto the seat of a chair that’s in front and to the side of you.

But when you stand on both legs, a tight iliacus tilts to the same side ilium anteriorly, arching and locking that side of the low back while leaving the opposite side in a tucked position, which often destabilizes it and can lead to both hip and low-back problems.

Releasing the iliacus nearly always helps the SI joint, low back and hips.

But there’s more.

It’s easy to understand that tense muscles lock joints. But the opposite is also true! If a joint locks up, the muscle has no other option but to shorten when the client gets off the table. When you release the muscle and the joint, the client will stay supple, open and strong.

The next time a client complains about low-back pain, think about the SI joint. Your client’s low back and hips will thank you.

Try It For Yourself: Assessing and Releasing the Sacroiliac Joint

Try these following techniques with clients you suspect may have issues with their sacroiliac joint (SI).

You can easily assess and work on the SI joint in a side-lying position.

1. Stand behind the client’s pelvis. Use your hand on the posterior superior iliac spine, knee or greater trochanter to slide one leg back and forth along the other leg like a piston. The top leg rests along the other the whole time. This maneuver mobilizes both sides at once because the other leg and pelvis are pinned to the table. You’re also automatically mobilizing both sides of the lumbar and thoracic spine and ribcage.
2. Facing the client lying on their side with their hips and knees at 90 degrees, tuck your hand or knuckles under the anterior superior iliac spine and you’ll find the iliacus. If the person is overweight or pregnant, they’ll always need iliacus work, and side-lying may be the only way to get to that muscle.
3. With your hand tucked under the ASIS, release the SI joint by reaching around the client’s pelvis as far as you can and drawing the pelvis over your hand toward you. It will be easier for the client to let go if you bring their pelvis toward your hand than if you push your hand into their pelvis/iliacus.

Related: Massage and Anterior Hip Replacement

Spotting Sacroiliac Joint Dysfunction

According to Veritas Health’s Spine-health, these are some of the most common symptoms of sacroiliac joint dysfunction. I’ve added some information specific to the work massage therapists do:

1. Lower back pain in the region of the PSIS or along the edge of the sacrum that feels dull, aching and can range from mild to severe. Typically, lower back pain related to sacroiliac joint dysfunction occurs on one side, but in some cases may be felt on both sides. Remember, the location of the pain isn’t always the location of the problem. For example, if there is fixity in one SI joint, the other side may hurt because it needs to move more to compensate.
2. Pain that spreads to the hips, buttocks and/or groin. One of the most common areas to feel SI joint pain is in the buttocks and upper back or side of the thigh. Again, pain is typically contained to one side, but may be felt on both sides in some cases. Often, SI-based pain will be more acute during walking, whereas lumbar disc pain will be more acute while sitting.
3. Sciatic-like pain in the buttocks and/or backs of the thighs that feels hot, sharp and stabbing. Numbness and tingling may also be present, and the symptoms may mirror sciatica, but rarely extend below the knee.
4. Stiffness and reduced range of motion in the lower back, hips, pelvis and groin that may make movements such as walking up stairs or bending at the waist more difficult.
5. Worsened pain when added pressure is put on the sacroiliac joint, such as when climbing stairs, running or jogging, and lying or putting weight on one side.
6. Instability in the pelvis and/or lower back that can cause the pelvis to feel like it will buckle or give way when standing, walking or moving from standing to sitting.