Sacroiliac Joint Pain: What Is It?

Medically Reviewed by Jabeen Begum, MD on January 28, 2025
7 min read

Injury, pregnancy, or uneven movement in your pelvis  can cause low back, butt, and leg pain that's often worse after you've been sitting for a while. This may be because the ligaments that hold your sacroiliac joint together get too loose or too tight.

Your sacroiliac (pronounced sa-krow-i-lee-ak) joints are some of the biggest joints in your body because they're where your spine connects to your pelvis. Pain in your sacroiliac joint is a common cause of low back pain. 

Sacroiliitis vs. SI joint dysfunction

Sacroiliitis is the medical term for inflammation (pain, swelling, and sometimes heat and redness) in your SI joint. You may get sacroiliitis when something irritates or damages one or both of your SI joints. This leads to inflammation that causes your back pain. You most often get it in one of your SI joints, which your doctor may call "unilateral sacroiliitis." But you can get it in both, and your doctor may call that "bilateral sacroiliitis."  

SI joint dysfunction is pain or discomfort, usually in your lower back and butt, due to irregular movement in your SI joints. Sacroiliitis is one potential cause of SI joint dysfunction.  

Your sacroiliac (SI) joints are where your spine (sacrum) and pelvis (iliac) connect. Your sacrum is the triangle-shaped bone at the bottom of your spine, and your iliac is made up of two fan-shaped bones. They join together at your SI joint to form your pelvic girdle or hips. If you look at someone's lower back, you can see the two sacroiliac joints as dimples on either side of their spine, low across their hips.

The main job of your SI joints is to shift the weight of your upper body to your hips and legs when you stand up and carry it as you walk. They also act like shock absorbers to keep all the structures in your upper body stable as you move around.

 

 

The most common symptom of an SI joint problem is low back pain, which can be a constant, dull ache or a sharp, stabbing pain. It may also:

  • Get worse after you've been sitting or standing in the same position or place for a while
  • Get worse when you turn your upper body or rotate your hips
  • Get worse when you've been standing with more weight on one leg than the other
  • Get worse when you climb stairs
  • Get worse when you run or take big steps while moving forward
  • Spread from your lower back to your hips, butt, thighs, and sometimes your feet
  • Feel numb or tingly in your legs

Your lower back and hips may also feel stiff for longer than an hour after you wake up in the morning.

 

 

SI joint pain is usually caused when the ligaments that hold your SI joint together get too loose or too tight. This can be because of:

  • A fall
  • A car accident
  • Pregnancy and childbirth
  • Surgery on your hips or spine
  • Uneven movement in your pelvis because one leg is shorter or weaker than the other, you have hip or knee problems, or you have other musculoskeletal problems

Causes of Sacroiliitis

Common causes of sacroiliitis include:

Arthritis. This is the main cause of sacroiliitis, and it can be from any type of arthritis, including osteoarthritis, ankylosing spondylitis, psoriatic arthritis, rheumatoid arthritis, and gout. Arthritis is just the medical name for joint pain, stiffness, and inflammation, and there are over 100 different types. For instance, osteoarthritis is the "wear-and-tear" arthritis that most of us get as we get older. Ankylosing spondylitis, psoriatic arthritis, and rheumatoid arthritis are all autoimmune conditions where your immune system mistakenly attacks your joints as if they were invaders, like bacteria and viruses. When your immune system attacks your joints, you get inflammation, pain, and joint dysfunction.

Inflammatory bowel diseases, such as Crohn's disease and ulcerative colitis. Inflammatory bowel disease causes inflammation in your digestive tract, which can spill over to other places close in your body, like your SI joint.

A reaction to a bacterial infection (reactive arthritis). You may get joint pain, stiffness, and swelling in your lower back, hips, knees, ankles, feet, and fingers about 10 days after you're infected with bacteria that cause a urinary tract or gastrointestinal tract infection. You may also get sacroiliitis from an overgrowth of bacteria called Staphylococcus aureus, which most people have on their skin and in their noses. 

Behcet's disease. This causes inflammation in your blood vessels that can lead to skin and joint pain, including in your SI joints.

Pregnancy. Hormones your body releases during pregnancy can make your SI joints stretch and move around. The added weight you carry can also change the way you walk, thus stressing your joints and causing inflammation.

Your doctor will usually do a physical exam on your back, hips, and legs. They may have you move your legs into different positions to check how far you can move before you feel pain. They may press on your SI joints or the area around them. They'll ask you questions about when you first noticed the pain and whether some activities make it worse. 

In addition, you doctor may order some tests, including:

  • Blood tests to check for infections or other causes of inflammation
  • X-ray of your pelvis to check for damage to your SI joint
  • CT scan
  • MRI scan

Your doctor may also try injecting a numbing medicine into your painful SI joint. If the medicine stops your pain, then it's likely that the SI joint is causing your pain.

Your treatment will depend on what's causing your pain and how bad it is. Your doctor will likely recommend a combination of the following: 

Physical therapy

This is the most common treatment for SI joint pain relief. Your physical therapist will give you a series of stretches and exercises to increase flexibility and strength in your hips. This will take pressure off your joints and stabilize them. You'll also learn to correct any habits you might have picked up when you were trying to avoid pain, like walking with a limp or leaning to one side. Your therapist may try ultrasound, heat and cold treatments,  and massage, as well as stretching and strengthening.

Medications

Potential medications include:

  • Pain relievers, such as nonsteroidal anti-inflammatory drugs (NSAIDs) you can get over the counter, like ibuprofen and naproxen. Don't take these for more than 10 days in a row. If these don't work, your doctor may prescribe stronger pain relievers.
  • Muscle relaxers, such as cyclobenzaprine, that can reduce the pain signals your muscles send to your brain
  • Biologics, such as adalimumab (Humira), etanercept (Enbrel), golimumab (Simponi), infliximab (Remicade), ixekizumab (Taltz), and secukinumab (Cosentyx), can treat many autoimmune conditions that may cause your SI joint pain
  • Disease-modifying antirheumatic drugs (DMARDs), such as tofacitinib (Xeljanz) or upadacitinib (Rivoq), that can decrease your inflammation and pain

Surgical and other procedures

Injections. Your doctor may inject your SI joint with cortisone to ease the inflammation and pain in your joint. You can only have this a couple of times a year because the steroids can weaken your nearby bone and tendons if repeated too often. If that doesn’t help, your doctor may try to numb the nerves around your SI joint to give you relief. 

Radiofrequency ablation. Your doctor may use a needle to permanently damage the nerve that sends pain signals from your SI joint to your brain. They may also freeze it with an injection, though that technique isn't used much.

Transcutaneous electrical stimulation (TENS). A small stimulator is implanted in your lower back that transmits an electrical current that blocks the pain signals from your nerves.

SI joint fusion. Rarely, your doctor may recommend that you have the two bones of your SI joint fused together surgically if other treatments haven't worked.

Alternative therapies

Prolotherapy. This is a complementary and alternative medical (CAM) therapy for chronic musculoskeletal pain. Your doctor injects a solution of saline and numbing drugs into your joint over several sessions every two to six weeks over several months. It's may help tighten loose ligaments in your SI joint, which can help ease your pain.

Manual medicine therapy.These use gentle joint stretching as well as forceful mobilization to treat chronic pain. This type of therapy is usually done by a chiropractor or a physical therapist.

SI belting. This is a band that you wear low around your hips to prevent your SI joint from rotating. It seems to work best for people with a lot of movement in their SI joint and muscle weakness. 

 

  • OTC pain relievers, such as ibuprofen, acetaminophen, or naproxen
  • Alternating ice and heat
  • Rest
  • Low-impact exercise like yoga and water resistance
  • Massage
  • Sacroiliac belt 
  • Changing sleep positions
  • Focusing on good posture

The ligaments that hold your SI joint together can get too loose or tight for a number of reasons. This looseness or stiffness is a common cause of low back, butt, and leg pain. Your doctor can help ease your pain using a number of treatments, such as physical therapy, medicine, and sometimes procedures like steroid injections.

How do I fix my SI joint?

Physical therapy is one of the most common treatments for SI joint pain relief.  Physical therapy can increase the flexibility and strength in your hips to take pressure off your joints and stabilize them. If this doesn't work, your doctor can also try medicines, steroid injections, or have you visit the chiropractor. Finally, your doctor may suggest you have surgery to fuse the bones in your hips to ease your pain.

What is the most common cause of SI joint pain?

Arthritis is the most common cause of sacroiliitis, which is inflammation in your SI joint. Sacroiliitis is a common cause of SI joint pain. But you could have pain because of an injury, pregnancy, or uneven movement in your pelvis due to biomechanical problems. Your doctor can help you figure out what's causing your SI joint pain.