What is SI Joint Pain?
Written by Neil Badlani, M.D., Chief Medical Officer, North American Spine

Dysfunction in the sacroiliac (SI) joint, more commonly referred to as the SI joint, can cause pain in the leg and/or the lower back. SI joint pain can be quite difficult to diagnose accurately since the radiating leg pain is much like that caused by a disc herniation, making them easy to confuse. 

In fact, doctors believed for many decades that the sacroiliac joint pain occurred because of back and leg pain, and difficulty in diagnosing the source even today leaves several in the industry skeptical. Modern estimates suggest the SI joint affects up to 30 percent of lower back pain sources.

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More About SI Joint Pain

lumbar foraminotomy

The SI joint is by the hip bones, connecting them with the triangular bone resting between the coccyx and the lumbar region of the spine. The SI joint serves to absorb the impact of every day movements to the pelvis, legs, and the upper body. 

Since it mostly acts as a cushion, the SI joint doesn’t really move around much–just small motions that help with bending and taking impact. It is supported by several strong ligaments that extend to other parts of the body. This soft tissue network supports the joint and helps take on some of the pressure. 

The piriformis muscle and the gluteus maximus also help support function in the sacroiliac joint.

The main parts to dysfunction in the SI joint are:

  • Too little movement may cause pain and muscle tension, both of which can restrict mobility. You may also feel pain down one buttock and in the lower back, much like sciatica pain. 
  • Too much movement may lead to pain and instability in the pelvis. You’ll typically feel this kind of pain in the hip or lower back, and sometimes in the groin. 
  • Sacroilitis, or inflammation of the scaroiliac joint, can lead to stiffness and pain in the pelvis. Dysfunction in the SI joint can cause this inflammation, or it could originally occur from a rheumatoid condition.

Young and middle-aged women are more susceptible to sacroiliac joint dysfunction, and pregnant women are at an even higher risk.

What are the symptoms?

The symptoms of SI joint dysfunction typically include:

  • Dull and aching lower back pain that may be mild or could feel severe. Typically, you feel this pain on just one side, but it can extend to both sides. 
  • Sciatic-like pain in the back of the thighs and/or the buttocks. This pain will feel like hot, sharp, stabbing pain that may or may not be accompanied by tingling and numbness. This pain rarely goes past the knees when the cause is sacroiliac joint dysfunction. 
  • Pain extending to the groin, buttocks, and/or hip. Similarly, it usually occurs on just one side but can manifest on both sides. The most common areas are the side of the thigh or the upper back. 
  • Increased pain when pressure is placed on the SI joint, such as when running, jogging, or climbing stairs, or when putting weight or lying on just one side. 
  • Stiffness or an otherwise restricted range of motion in the groin, pelvis, hips, and lower back, all of which can create a problem with bending at the waist, walking upstairs, or similar types of movement. 
  • Lack of stability in the lower back or pelvis, which can cause the latter to feel like it will suddenly give way when sitting down, standing up, or walking. 
  • Aggravating the SI joint can also lead to sacriliitis, which is inflammation of the SI joint. This can cause stiffness, pain, and a host of other symptoms.

How is SI Joint Pain Diagnosed?

There isn’t just one test that can pinpoint sacroiliac joint dysfunction, so it is important to combine various diagnostic test results to paint a complete picture for a diagnosis. 

Similarly, it’s hard to properly diagnose SI joint dysfunction because the symptoms it causes are quite similar to other conditions that are common, like back pain from facet joint arthritis or leg pain from a lumbar slipped disc. 

Diagnosis always begins with an interview regarding symptoms, followed by a physical examination and possibly an injection to relieve pain in the medium-term. 

Medical History

The doctor will collect your medical history, which includes any past or recent injuries, exercise habits, sleep hygiene, diet, and current symptoms you are experiencing. You will also discuss whether you have tried any treatment methods in the past for your SI joint pain, and whether any of them had an effect or not. 

Several provocation tests are available to try and rule out other causes of the pain or help pinpoint the SI joint as the problem. These tests include:

  • Sacral thrust test: The doctor applies pressure to the back of your hips as you rest in a prone position on the table. If this action causes pain, the test results will be “positive.” 
  • Distraction test: Here, you lay belly up and pressure is applied to the anterior part of the hips. Likewise, if this produces pain, the test is “positive.” 
  • FABER test: This is a test where you remain on your back, keep one leg straight, and make the other foot touch the inner straight knee. Then, the doctor gently pushes the bent knee to apply pressure to the SI joint. In some cases, the doctor may move the knee from side to side or up towards the chest, but downward is the most common. If there is pain or too much restriction of mobility, then this is considered a positive test result that can indicate SI joint pain. 
  • Palpation tests: The doctor simply applies pressure right on the sacroiliac joint itself. If there is tenderness on the joint when applying pressure, then the test is positive and should be evaluated along with the other positive tests. If there are clusters of symptoms in the right area, then sacroiliac joint dysfunction can likely be diagnosed.

What are the causes of SI Joint Pain?

low back pain

There are certain factors that can cause and increase your risk for developing sacroiliac joint dysfunction and the pain associated with it, including but not limited to:

  • Pregnancy or childbirth commonly result in SI joint pain due to hormonal changes weakening the SI joint’s ligaments, natural weight gain, and changes to the pelvis due to childbirth. Some women may have loose ligaments after they give birth, allowing instability and dysfunction to continue. 
  • Gait issues, including scoliosis or leg length discrepancy, can result in undue pressure to just one side of the pelvis, resulting in an unbalanced wear and tear and a higher likelihood of developing SI joint pain. 
  • Previous lower back surgery can create pressure on the SI joint that was not there before. One study noticed that this type of pain is relatively common after undergoing a fusion surgery. This study also noticed that undergoing a multi-level surgery puts patients at a higher risk of developing SI joint pain compared to those who undergo a single-level procedure. For example, SI joint pain can occur after a bone graft or hip joint replacement surgery. 
  • Activities that pressure the SI joint, such as a labor-intensive job or contact sports, can contribute to SI joint pain. This is especially true if the lower back muscles or the pelvic muscles are not conditioned for the recurring activity.

Regardless of the cause, pain in the SI joint can happen rather slowly and without a single obvious cause to pinpoint to, unless it is the result of trauma or an injury to the joint.

How is SI Joint Pain treated?

Conservative Options

Conservative treatment options include nerve root blocks and steroid injections. These are designed to provide temporary relief (up to one year), and you may elect to have the procedure done multiple times. Other conservative strategies may include the placement of a spinal cord stimulator–or STIM–which is designed not to correct the underlying degeneration, but to lessen the pain the condition causes.


Minimally invasive decompression surgery aims to relieve pressure on the nerves of the spine. This pressure is often caused by stenosis, bulging or herniated discs, and more. Relieving this pressure can be achieved by reducing or removing soft tissue (disc material or scar tissue) or bone (bone spurs, a section of the lamina or foramina) to decompress the affected nerve. When the compression is caused by soft tissue material, a surgical laser may be used to shrink the impinging material.


Fusion surgeries are similar in goal–to remove damaged disc tissue and fuse the bones together–but differ in approach, including the use of specialized hardware to reinforce stability, and the location used to gain access to the spine. A related procedure is an artificial disc replacement, in which a damaged cervical disc is replaced with a synthetic disc, and the vertebrae are not fused.

How Much Does Treatment Cost?

Treatment cost depends on several factors, especially what insurance you have and how much of your deductible has been met. IN the last two years, 90% of our patients have paid less than $2000 out-of-pocket. Some have paid literally nothing, and other have paid much more than that. It depends. The good news is: our Patient Care Managers will handle as much as they can directly with your insurance company, and all your costs will be known up-front.

Important note: spine surgery often pays for itself within a year or two. Many people actually spend more money trying to live with the pain than they do getting the pain fixed. The following calculator is intended to give you a sense of what you spend on managing—rather than eradicating—your pain.

Calculate how much you've spent on back pain this year.


This past year you have spent on your pain treatment:

Get surgery now. Getting surgery now is the smartest financial move. Over the last two years, the average North American Spine patient spent around $2,000 out-of-pocket for treatment. You’ve spent that much or more this year to manage your back pain than you could to fix it.

Get surgery soon. Over the last two years, the average North American Spine patient spent around $2,000 out-of-pocket for treatment. At your current rate, you will spend that much or more within the next two years. The sooner you get treatment, the sooner it will pay for itself.

Keep an eye on your spending. Currently, you are managing your pain efficiently from a financial perspective but over time, your expenses could add up. Surgery should be strongly considered if you start missing more work or spending more on treatment medication.

Great job! You are spending very little on your back pain. Keep it up!

Equipment Used in Diagnosis and Treatment of SI Joint Pain

Once the doctor has collected a complete record of your medical history and has conducted an exam, he or she may need to perform a number of tests to further confirm the diagnosis in case the physical check isn’t clear. Some of these tests include:

  • Sacroiliac joint injection, also known as a sacroiliac joint block, occurs when the doctor numbs the SI joint with bupivacaine or lidocaine to see if the pain continues or not. If it does, then the doctor knows the SI joint is to blame for the pain you are feeling. 
  • Fluoroscopic guidance is a so-called “live” x-ray that examines the joint with a needle and the help of ultrasound guidance.

By getting an x-ray, a CT scan, or an MRI, you will be able to help the doctor rule out any other potential causes for the pelvic pain and back pain, such as a tumor, infection, facet joint arthritis, or a slipped disc.

How Does SI Joint Pain Compare to Other Spine Conditions?

There are many medical conditions that impact the sacroiliac joint that may mistakenly lead doctors to blame it:

  • Adjacent segment disease: When something breaks down after a previous spinal fusion surgery 
  • Ankylosing spongylitis: A rheumatic condition that causes the joints to eventually become fused on their own due to inflammation, leading to a reduced range of motion as well as stiffness in the joints. It can also impact the hips and similar joints in the region. 
  • Degenerative osteoarthritis: This is a natural wear and tear from arthritis 
  • Degenerative sacroilitis: When one of both SI joints are inflammed naturally over time  
  • Leg length discrepancy: Both legs are not the same length
  • Ligamentous laxity: When a ligament becomes lose from hypermobility 
  • Sacroiliac joint disruption: Whether from too much or too little motion, abnormal SI joint motion 
  • Sacroiliac joint infection: Tissue damage can occur from bacterial or viral infections of the SI joint 
  • Sacroiliac joint inflammation: Self-explanatory 
  • Trauma: A high-impact sport or a car accident could damage the SI joint 
  • Tumor

As always, speak with your doctor to ensure you are getting the correct diagnosis and treatment for your problem.

Analogy: A Bicycle

Riding a bike without a seat is no fun. You have limited connection to the body of the bike, you may find you lack stability when riding, and, ultimately, it’ll hurt whether you sit or keep standing! The same is true for SI Joint Pain. Because the SI Joint connects the spine and the hips, damage to it can create both pain and instability. The good news: our docs are so good that for them fixing SI Joint Pain is like riding a bike.

Good Bicycle

Bad Bicycle

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