The sacroiliac joint (or SI joint) is a very important area of the body (located in the lower back) that is susceptible to pain and injury. It is estimated that up to 25% of cases of lower back pain may be caused from a problematic SI joint.

In this blog, you’ll learn everything you need to know about the sacroiliac joints and SI joint pain (also referred to as SI joint dysfunction), its common symptoms, and what you can start doing today to reduce pain.

• What are the sacroiliac joints? What do they do?
• What are some symptoms of sacroiliac joint pain?
• What are some causes of sacroiliac joint pain?
• Three muscles that affect sacroiliac joint pain
• Three ways to improve your sacroiliac joint pain

What are the sacroiliac joints? What do they do?

If you were to place your hands at the base of your lower back, you’d likely feel two “bumps” on the back side of your pelvis. Sometimes also referred to as “dimples” in your lower back, this is where your sacrum connects to the ilium bones and forms the sacroiliac joints. There are many soft tissues (muscles, ligaments, cartilage) that hold the SI joints in alignment and support the small, yet very important, movement that occurs in this joint with every single step that you take.

The SI joints provide stability in the body, helping to support your body weight and distribute external forces (e.g. lifting, picking up your kids) evenly across the pelvis to reduce pressure placed on the lumbar spine. They also absorb shock and impact (e.g. playing sports, stepping off of the sidewalk, landing each step during a run), helping to efficiently transfer energy between the lower and upper halves of the body.

What are some symptoms of sacroiliac joint pain?

The symptoms of sacroiliac joint pain may vary slightly from person to person.

The pain is often felt in the lower back and upper buttocks region, the immediate area around the SI joint. Some people describe the pain in this location as being dull and achy, while others may experience more of a stabbing, sharp pain in the lower back.

Other symptoms of sacroiliac joint pain include radiating pain down into the hips, groin, and back of the upper thigh. Additional feelings of tightness, stiffness, burning, tingling, numbness, or weakness may be present and describe some of the sensations felt on the painful side.

Certain activities or body movements typically performed on a daily basis may become more challenging and also increase the symptoms. Examples include: twisting or leaning back towards one side; lying down or sleeping on the affected side; going up and down stairs; stepping off of the sidewalk; and sitting, driving, standing, or walking for too long.

What are some causes of sacroiliac joint pain?

Common causes of sacroiliac joint pain include (but are not limited to) misalignment of the pelvis, traumatic events or past injuries, pregnancy, hypermobility, sports, and more. We’ll share our view on each of these potential causes in more detail below.

Misalignment of the pelvis (pelvic torsion and anterior pelvic tilt) can cause SI joint pain

Pelvic torsion is where one side of the pelvis rotates forward into an anterior position relative to the other side, creating a twist in the pelvis. This rotation changes the orientation of the sacrum and ilium bones, affecting the way that they move relative to each other. As these structures begin to rub each other the wrong way, the soft tissues of the SI joint wear away and become irritated over time.

Why is my pelvis twisted?

This misalignment happens as the result of muscle imbalances that develop and hold the pelvis in this off-balanced position, such as a tighter iliopsoas on one side. The iliopsoas is your body’s main hip flexor, consisting of both the psoas muscle and the often overlooked iliacus muscle -- which you will learn more about as you keep reading.

A rotated pelvis is also a common contributor to other conditions, such as scoliosis, leg length discrepancy, and many single-sided pains in the body. Don’t blame these other “diagnoses” as the root cause of your sacroiliac joint pain. It all stems from the rotated pelvis caused by muscle imbalances around your hips.

Anterior pelvic tilt is a misalignment of the pelvis where both sides of the pelvis rotate forward into an anterior position, creating an excessive arch in the lower back. Some strain is placed on the SI joints in this position, with a lot more force being placed on the joints of the lumbar spine.

SI joint pain caused by traumatic events or past injuries

Traumatic events, such as a car accident or falling on your tailbone, can force the pelvis out of alignment and cause pain in the SI joints. Similarly, past injuries (or surgeries) to the foot, ankle, knee, or hip can lead to compensations in the way you move your body. Over time, this creates muscle imbalances (which we talked about above) that work their way up towards the pelvis, impacting its alignment and also the way movement occurs in the sacroiliac joints.

SI joint pain after pregnancy

A recent survey of 1,000 women found that a significant majority of them were unaware that sacroiliac joint pain is one of the leading causes of lower back pain in women 35 years and older who have been pregnant in the past.

When a woman is pregnant, a hormone called relaxin is released into the body. As you may have guessed by the name, this hormone helps the muscles and ligaments in the woman’s pelvis to relax. This supports a growing fetus and also allows for more laxity and expansion in the joints of the pelvis for the child to pass through the birth canal during delivery.

As amazing as pregnancy and childbirth can be, these events can later lead to developing sacroiliac joint pain. While the relaxin helps make childbirth possible, it also has the effect of increasing the instability of the woman’s pelvis (which is a naturally stable area of the body). Because relaxation of the pelvic joint ligaments (which include both the SI joints and the pubic symphysis) creates additional stretch and movement, the surrounding muscles and ligaments hold tension in an effort to create stability in those joints to protect the body.

There may even be pre-existing muscle imbalances or asymmetries in sacroiliac joint laxity on either side of the pelvis before the pregnancy, which later contributes to developing pain in the SI joint during and/or after pregnancy as the surrounding muscles and ligaments experience stress and hold tension.

SI joint pain caused by hypermobility

People who are hypermobile, or those who participate in sports and activities such as gymnastics or yoga, tend to have “looser” joints. Think about someone who can perform the splits. While they can move into a larger range of motion than the average person, the joints in their body are typically less stable. To protect the body, the brain sends signals to the surrounding muscles to hold tension to help stabilize the joints in these extended positions. This tension can compress the SI joint and contribute to muscle imbalances where one side of the body has more range of motion than the other.

SI joint pain from golf, baseball, or football

Collision sports (such as football or hockey) and rotational sports (like golf or baseball) can play a role in the development of sacroiliac joint pain in athletes.

Taking a hard hit in football or receiving a hip check in hockey when you are least expecting it can have an impact on the body. A collision such as this can have enough force to knock the structures of the pelvis and the body out of alignment, leading to the athlete experiencing pain in the SI joints.

The demands placed on the body during that of a golf swing or a baseball swing can be significant. There is a certain amount of rotation required to be coming from the hip joints and the thoracic spine during a “perfect” swing in order to protect the joints in the lower back and pelvis. When range of motion in these areas is lacking, movement must be created elsewhere (like in the lumbar spine and SI joints). These areas are meant to be stable, and this increased movement can place a constant shearing force on these joints, leading to pain developing over time after hundreds and thousands of swings irritating those areas.

These are just a few examples; other sports and activities can certainly contribute to developing pain in the sacroiliac joints. Think about what we’ve already talked about above and consider how it applies to the things you do in your life.

Three muscles that affect sacroiliac joint pain

While there are over 40 different muscles in the lower back, hips, and glutes that surround the sacroiliac joints in your body, we believe that the iliacus, piriformis, and quadratus lumborum muscles are among the most important ones for you to focus on first to improve your pain.

How does the iliacus cause SI joint pain?

The iliacus muscle lines the inside surface of the pelvic bone (or ilium) and connects to the iliac crest and iliac fossa on the ilium, the top edge of the tailbone (the ala of the sacrum), and the lesser trochanter (the inside of the femur near the groin).

The primary function of the iliacus is to stabilize the hip joint and the sacroiliac joint (or SI joint), keeping those two joints aligned and strong regardless if the body is stationary (such as when sitting or standing) or if the body is moving (such as when walking or running). Other secondary functions of the iliacus include assisting in hip flexion and hip external rotation.

Since the iliacus is active when sitting, standing, walking and running, it is being used constantly throughout the day, increasing the likelihood of this muscle becoming chronically tight. Tightness in the iliacus muscle pulls the pelvic bone forward into an anterior rotation, where the lower back is chronically arched.

This creates strain where the sacrum and ilium meet – the SI joint! The longer these structures are misaligned, the more unhappy they become, and the more likely you’ll develop pain or discomfort in this area.

How does the piriformis cause SI joint pain?

The piriformis muscle connects to the sacrum, the ilium, and the greater trochanter on the femur. Its primary functions include assisting with external rotation and abduction of the hip, as well as stabilizing the hip inside of the hip socket.

When the piriformis becomes tight, it pulls on the sacrum and ilium and can lead to compression or misalignment about the SI joint. As you continue to move your body with these supporting muscles not functioning optimally, the sacrum and ilium rub each other the wrong way and cause the soft tissues inside the joint to become irritated.

A tight piriformis muscle often goes hand-in-hand with tight hip flexors, like your iliacus and psoas muscles. This is because your body is searching for balance on each side of the hip. If the hip flexors on the front of the hip are tight and pulling the pelvis into an anterior position, the muscles on the back side of the hip (like the piriformis) will tighten up and play a game of tug-of-war. This combination of a tight iliacus and tight piriformis is very common among people who are experiencing SI joint pain.

How does the quadratus lumborum cause SI joint pain?

The quadratus lumborum muscle (or the QL muscle for short) attaches to the bottom of the 12th rib and the transverse processes of the L1-L4 vertebrae and connects to the iliac crest (of the ilium) and also the iliolumbar ligament, which helps to stabilize the sacrum and the sacroiliac joints.

The quadratus lumborum muscles function together to help extend the lumbar spine, and they can also function unilaterally to side bend the spine. With its connection to the bottom rib, the QL also functions to stabilize the diaphragm when you inhale with each breath.

A tight quadratus lumborum muscle pulls on the ilium and iliolumbar ligament that it attaches to. This may result in a rotation of the pelvis or a hip hike on one side of the pelvis, changing the alignment between the ilium and sacrum. As we’ve discussed with the other muscles, this ultimately affects the movement of the SI joints and can lead to pain.

Three ways to improve your sacroiliac joint pain

The key takeaway here as it relates to keeping your SI joints happy and healthy revolves around good alignment. Throughout the course of our lives, there are so many things that contribute to the development of muscle imbalances that pull us out of alignment and cause pain.

You absolutely must take care of the muscles that support the movement of the pelvis so that the ilium, sacrum, and other structures can move efficiently and work together as they were designed to do. The pelvis is part of the “core” of your body, and when it is well-supported and in good alignment, the rest of the body works better.

Do these 3 things to improve SI joint pain

1) Release the tight muscles surrounding your pelvis.

We already talked about 3 muscles that may be tight and contributing to your sacroiliac joint pain. Explore each of those muscles with muscle release techniques and stretches to reduce tension and tightness that has built up in them, likely over YEARS.

The piriformis and quadratus lumborum muscles can each be easily accessed by a massage therapy ball or lacrosse ball (or similar), as these muscles are more superficial. However, the iliacus muscle, one of your body’s main hip flexors (along with the psoas muscle), is a little bit different and is not easily accessed by a ball to truly get the right amount of pressure and precision needed for an effective release. For this, you need to see a manual practitioner or have a special tool that can do the job.

My favorite muscle release tool for the iliacus muscle is the Hip Hook. The Hip Hook was invented by Christine Koth, MPT, who was a physical therapist for 20+ years and noticed a common theme among the patients she worked with – tight hip flexors! When the hip flexors get tight, they can cause pelvis alignment issues and create tons of problems throughout the body.

The Hip Hook is designed to get into the hard-to-reach psoas and iliacus muscles (your body’s main hip flexors) to relieve tension, increase range of motion, and decrease pain. Other tools and therapy balls simply don’t address BOTH of these muscles, which may be key to long-term pain relief and improvement.

2) Strengthen the muscles surrounding your pelvis to improve muscle imbalances.

Reducing tension and tightness with muscle release work and stretching alone may not fully address the “root cause” of your sacroiliac joint pain. It is likely that these muscles are compensating and trying to perform the work done by other, larger muscles that have weakened (perhaps from too much sitting, inactivity, past injuries, etc.).

Some of these areas that often become weak on people (and maybe on you too) include the glutes, hamstrings, core, and smaller hip stabilizers around the pelvis. Try waking them up with some of these hip strengthening exercises and see how your body feels.

3) Work on exercises specific to improving your hip mobility.

Adding direct hip mobility exercises into your routine is another way that you can strengthen the muscles that support the movement of your hips and improve the active range of motion through which you can control your hip joints. This is not to be confused with stretching, which simply takes the hip through its passive range of motion.

These can be some really amazing hip mobility exercises that you can try to start improving how well your hips move, helping to keep your pelvis aligned in better position, and reducing the pain that your SI joints may feel.

Looking to learn more about your body?

You’ll get answers to your questions about tight hip flexors and learn how they can affect the functioning of your entire body. Discover the “3 Simple Steps” to realigning your pelvis and improving the way your body feels in the book “Tight Hip, Twisted Core - The Key To Unresolved Pain” by Christine Koth, MPT.

Frequently asked questions about sacroiliac joint pain

What do the sacroiliac joints do?

The SI joints provide stability in the body, helping to support your bodyweight and distribute external forces evenly across the pelvis to reduce pressure placed on the lumbar spine. They also absorb shock and impact, helping to efficiently transfer energy between the lower and upper halves of the body.

What causes sacroiliac joint pain?

Sacroiliac joint pain can be caused by several different factors, including (but not limited to) misalignment of the pelvis, traumatic events or past injuries that resulted in compensations, pregnancy, hypermobility, and sports.

How do I relieve sacroiliac joint pain?

Relieving sacroiliac joint pain centers around being able to improve the way the pelvis is aligned, which in turn helps the sacrum and ilium move better together and reduce pain. This can be achieved through a combination of muscle release and strengthening, stretching, and mobility exercises that address currently existing muscle imbalances around the hips and pelvis.