Sacroiliac arthrodesis: Fusion of the sacroiliac joint

Article reviewed and approved by Dr. Ibtissama Boukas, physician specializing in family medicine

Most sacroiliac joint pain is treated conservatively (medications, physical therapies, infiltration, etc.). On the other hand, the operation may be necessary when non-surgical treatments prove ineffective. Sacroiliac arthrodesis is sometimes used to treat these special cases.

What is sacroiliac arthrodesis, and what are the indications for it? How is the procedure performed, including the risks and potential complications? How is post-surgical rehabilitation going? This popular article explains everything you need to know about this operation.

Definition and anatomy

To better understand sacroiliac arthrodesis, it is necessary to explain the sacroiliac joint from an anatomical and physiological point of view.

The sacroiliac joint connects the bones of the pelvis (called the iliac) to the sacrum, a triangular bone located below the vertebrae lumbar. The main function of the sacroiliac joints is to absorb shocks, and to increase the stability of the trunk.

It is believed that the sacroiliac joint is responsible for 15 to 30% cases of low back pain. Among the main causes of sacroiliac pain are trauma, anatomical deformities (such as scoliosis or a difference in the length of the lower limbs), inflammatory pathologies, infection, etc.

The diagnosis of sacroiliac involvement is not always easy to establish. A clinical examination integrating several specific tests can highlight a dysfunction of this joint. It should be noted that there is no single test indicating that the sacroiliac joint is the source of pain. Rather, it is a combination of tests that can point to damage to this joint.

The use ofmedical imaging can also help clarify the diagnosis. This may be an x-ray, CT scan, magnetic resonance imaging (MRI), etc. This will make it possible in particular to eliminate another lumbar disorder that can reproduce similar symptoms, such as:

Sacroiliac dysfunction causes symptoms such as lower back pain radiating down the leg (hip, buttock, groin, thigh, Calf), stiffness in the hips or pelvis, or instability in some cases.

Typically, first-line treatment includes medication and physical therapy (physiotherapy, osteopathy, exercises, etc.).

When these modalities do not improve the symptoms, we consider thesacroiliac infiltration. This can either be for diagnostic purposes to confirm sacroiliac involvement and establish a definitive diagnosis, or for therapeutic purposes in order to relieve pain. It essentially consists of inject a local anesthetic and/or an anti-inflammatory agent in the sacroiliac joint.

If the symptoms do not subside despite the use of the methods mentioned above, the doctor will sometimes resort to surgery to relieve the patient and improve his quality of life. In this perspective, sacroiliac arthrodesis is a potential intervention.

Sacroiliac arthodesis: Indications

The decision to proceed with arthrodesis of the sacroiliac joint will always be made jointly with the patient. Many factors will have to be taken into account, including the effectiveness of conservative treatments, the chances of success of the operation, potential complications, post-surgical rehabilitation and the impact on quality of life.

When the following symptoms persist for several weeks or months and do not respond to well-conducted non-surgical treatment for at least 3 months, arthrodesis of the sacroiliac joint may be recommended. In general, it persists:

  • Severe pain in the lower back or lower limb that makes it difficult to carry out activities of daily living. This pain is usually unilateral.
  • An instability of the pelvis which can cause pain with prolonged standing, walking or getting up from a chair. The pain may also worsen when climbing stairs up a hill.
  • Stiffness and limited mobility in the lower back, hips, or pelvis.
  • Difficulty sleeping and/or functioning on a daily basis.


The goal of sacroiliac arthrodesis is to fuse the sacrum to the iliac bone to promote bone growth across the joint. This fusion will be performed using surgical instruments and/or bone grafting, and will allow the joint to be welded together during the healing process following surgery.

There are various surgical methods, the most popular being minimally invasive sacroiliac fusion through a small incision in the buttock. Some operations involve open surgery, but the higher risk of complications and less encouraging results mean that this type of surgery is now rarely performed.

Minimally invasive sacroiliac arthrodesis

A typical sacroiliac joint fusion procedure usually includes the following basic steps:

  • The patient lies prone (prone) on the operating table, under general anesthesia.
  • A small incision (2 to 3 centimeters) is made in the side of the buttock (through the gluteal muscles) to access the ilium.
  • The implant instruments are then placed in place using screws, pins or a mallet.
  • If a bone graft is needed, the sacroiliac joint is cleared of cartilage and soft tissue, and a bone graft is placed in the joint space. The bone graft is usually taken from another area of ​​the ilium.
  • The incision site is then irrigated using a saline solution which removes debris from the wound before closing it. Then the incision is closed in several layers using standard sutures.

The operation usually lasts an hour. Fluoroscopic imaging is used throughout to ensure that the sacroiliac joint is reached, and to allow the surgical material and bone graft to be implanted appropriately.

Risks and complications

Sacroiliac arthrodesis have a low risk of complications, especially if performed minimally invasively. It is rather open surgery, rarely practiced these days, which is more risky.

Obviously, this intervention still has possible complications during or after the operation, like any surgical intervention. Potential risks include:

  • infection
  • excessive blood loss
  • complications due to anesthesia
  • etc.

Furthermore, a potential complication that is important to mention is the compensation of adjacent segments. As the fused sacroiliac joint will no longer do its job of shock absorption and mobility of the pelvis, it will transmit the pressure to another vertebral segment which will have to compensate.

This leads to an overload at the level of the L5-S1 segment (lumbar-sacral joint) which could cause pain and lumbar instability. Besides, a survey revealed that new problems in the lumbar spine occurred in approximately 5% of patients within six months of sacroiliac joint fusion.

Rehabilitation following sacroiliac arthrodesis

Rehabilitation and healing time after sacroiliac arthrodesis will depend on several factors. The type of surgery (implants, graft, etc.) will have a lot to do with it, as will the severity of the symptoms present even before the surgery.

Since the bones continue to fuse together during the healing period following the operation, persistent pain and other symptoms are to be expected. Fortunately, these will usually start to subside within a few weeks. In all, the recovery process can take up to 6 months.

To optimize rehabilitation, the following modalities may be implemented:

Pain management 

Most patients who undergo sacroiliac arthrodesis are discharged from the hospital the day after the operation. We can then prescribe the following elements to improve their comfort and reduce their pain:

  • A walker or cane to reduce stress on the sacroiliac joint as it fuses.
  • A lumbar belt to stabilize the joint and limit movements that may exacerbate pain and impede healing.
  • Analgesics to manage postoperative pain (ranging from painkillers, anti-inflammatories to opioids depending on the case).


The goal of post-surgical physiotherapy (physiotherapy) is to regain function and reduce pain. It is most often prescribed by the orthopedic surgeon, and includes the following modalities:

  • heat and ice
  • electrostimulation (TENS)
  • massage and mobilizations
  • aquatic therapy
  • therapeutic exercises and stretching
  • education and home program
  • etc.



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