How A PSIF Procedure Can Help Patients With SI Joint Pain

What Is the Sacroiliac Joint? | What Causes SI Joint Pain? | How Can a PSiF Procedure Help? | PSiF Procedure Benefits | Learn More

Lower back pain is a common condition, with up to 80% of the U.S. population suffering from it at some point. Up to 25% of lower back pain originates in just one place: the sacroiliac joint. This critical juncture in the pelvis provides both stability and small movement that helps us ambulate without wobbling or falling over. As we age, the structures in this region of the body, commonly helped along by childbirth or other conditions both acute and chronic, cause this joint to weaken and fail. This leads to debilitating pain and a feeling that your knees might literally buckle underneath you. But there is help for a compromised SI joint. The posterior sacroiliac fusion (PSiF) procedure is a minimally invasive solution to a life-altering pain condition. Here’s what you should know.

What Is The Sacroiliac Joint?

The sacroiliac joint is one of the largest joints in the body. It connects your spine to your pelvis and consists of: 

  • The sacrum: A bony triangle at the base of the spine, just above the tailbone
  • The ilium: The upper point on the pelvis and one of three bones that make up the hip bones 

The bones of this joint are not exactly matched, but they fit together and are supported by muscles and ligaments. The inside of this joint is lined with cartilage, and extra space between bones and other structures is filled with lubricating fluid. Floating in these open spaces are nerve endings, too.

The match of bones and tendons is a complicated puzzle that lends stability to the pelvis but also allows for the movement needed to keep us upright and to give birth.

What Causes SI Joint Pain?

Sacroiliac joint pain is characterized by not only hip pain but also pain that occurs in the lower back, buttocks, and pelvis. This pain can be radiating or feel like burning in the pelvis.

Other symptoms might include:

  • An increase of pain when moving from seated to standing
  • Numbness and weakness in the legs
  • A feeling of instability in the legs
  • Stiffness or limited mobility in the pelvis

Some people find that their sacroiliac joint pain gets worse when:

  • They stand for long periods of time
  • Their weight isn’t balanced over both legs
  • They climb stairs or run
  • They take larger than normal steps

SI joint pain can be caused by both acute and chronic conditions.


In the weeks and months before childbirth, a hormone called relaxin causes the ligaments in the hips to get very loose. This ligament laxity is normal and necessary to allow the pelvis to open for vaginal birth. 

Although this loosening is typical and healthy, the additional weight of pregnancy coupled with a change in a pregnant person’s gait may cause injury or damage to the joint that does not heal after childbirth. People who are pregnant are most at risk for SI joint pain, and their risk of developing arthritis in this joint is higher, too.


Osteoarthritis is a form of wear-and-tear inflammation that occurs as the joint wears down over time and with use. Cartilage that protects the joint thins, and lubrication decreases. This causes painful, bone-on-bone rubbing in the joint that can be debilitating.

Ankylosing spondylitis 

Ankylosing spondylitis (AS) causes the immune system to attack itself. This creates inflammation in the body, primarily in the SI joint. In extreme cases, this autoimmune disorder creates new bone that painfully and improperly fuses joints together.

This condition is chronic and can also affect the internal organs and the eyes.


Tucked as it is inside the strong bones of the pelvis, most injuries to the SI joint occur in full-contact sports or falls.

Uneven gait

How we walk affects everything, and the SI joint is no different. Some people develop an uneven gait to compensate for another injury, while others simply fall into an uneven walking pattern that they don’t even know they have.

Pregnant people experience this when they compensate for a growing belly. In many cases, SI joint pain due to a temporary change in gait during pregnancy resolves itself after birth.

How Can A PSiF Procedure Help?

The PSiF procedure is a SI joint stabilization surgery that has been available since 2014. For many people whose pain has not responded to more conservative treatments, it can relieve pain and restore the proper level of mobility in the joint.

This SI joint stabilization procedure is minimally invasive and can be performed through a small incision in the back. This is typically safer than the traditional lateral approach. From start to finish, the procedure usually takes less than 30 minutes, and patients leave the surgical center the same day.

The procedure is very simple. You’ll change into a surgical gown that opens in the back and position yourself face down on the table. This procedure is done under local anesthesia, but talk to your doctor if you are nervous about feeling pain. They may be able to offer you a mild sedative prior to the surgery. 

Once the surgical site is cleaned and numbed, your doctor uses fluoroscopy to guide a piece of donor bone to the site that requires stabilization. Here’s how.

  • The joint is lined up using a seeker guide pin so that the sacrum and iliac bones are at the proper angle and depth.
  • A small incision is made so that the other surgical tools can be placed.
  • A drill opens up a small hole in the bone.
  • An allograft implant — an implant from a donor — is attached to an inserter device. 
  • The pain specialist places one implant at a time. These are usually less than three centimeters each. The joint may require one or two implants secured with an epoxy to encourage fusion.
  • Once the implants are in place, the small incision is closed with stitches or staples.

The PSiF procedure is best for people who have not found relief with typical treatments for SI joint pain that include:

  • Rest
  • Ice
  • Non-steroidal anti-inflammatory drugs (NSAIDs)
  • Improving gait and posture

Your doctor may recommend a diagnostic injection to confirm that the SI joint is the site of the pain. People who experience a 50% or more reduction in their pain after two injections are considered good candidates for the PSiF procedure.

PSIF procedure benefits

The benefits of the PSiF procedure include: 

  • An increase in mobility
  • A reduction of pain scores
  • A low incidence of reoperation

Recovery time is a fraction of what it was with traditional lateral procedures, and the use of donor bone offers better rates of fusion success. 

The International Society for the Advancement of Spine Surgery (ISASS) released a statement acknowledging the 15 to 25% of lower back pain that originates in the SI joint and touting the efficacy of spinal bone fusion, specifically in a posterior approach, to treat it. They pointed out the low rate of surgical complications, the faster recovery times, and the improved patient outcomes.

PSIF procedure risk factors

The PSiF procedure is remarkably safe, but every procedure comes with risks. Common risks of this SI joint stabilization surgery include:

  • Bleeding or bruising at the incision site
  • Infection
  • Increase in pain
  • Nerve damage

Other risks of this surgery include the potential failure of the allograft bone to fuse with your bone. This procedure may also not relieve the pain you are experiencing, often due to a misdiagnosis of the cause of the pain.

Another potential risk is adjacent joint disease that occurs when the shock absorbing disc and cartilage is removed to place the implant. The pressure that was formerly absorbed in this area is then moved above and below the affected joint, which can cause more pain and degeneration in the lumbar spine and facet joints.

PSIF procedure recovery

Your pain specialist will provide you with specific recovery guidelines, but some general rules apply for surgical procedures.

You will need someone to drive you home on the day of your SI joint stabilization procedure. Take the day off to rest and relax. If you are prescribed pain medication, take it according to directions and do not exceed the amount prescribed.

If you experience pain after your prescription is completed, most people find relief with ibuprofen.

You may have soreness at the incision site. This is normal and should resolve within a few days. If the incision becomes more painful, gets red, or oozes, talk to your doctor, as this may be a sign of infection. Fever and a general feeling of being unwell are also cause for concern.

Avoid strenuous activity for two weeks, only returning gradually after your doctor gives you the greenlight. It’s important to allow yourself time to heal, so be patient if you are still experiencing soreness.

If your SI joint dysfunction is due to an uneven gait, your doctor may recommend physical therapy and gait training. This helps you to retrain your body to walk in a more balanced manner.

Everyone recovers at a different rate. People with strenuous occupations may not be fully cleared to return to work for a month or more, while others might be back at their regular activities in no time. Talk to your doctor about which recovery timeline you might expect.

Learn More At Arizona Pain

At Arizona Pain, we understand that SI joint pain can be debilitating. In addition to a wide variety of diagnostic tests and holistic treatments, we offer the PSiF procedure to relieve pain and help you get your life back. Get in touch to set up an appointment today.