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What’s a Sacroiliac Joint Fusion?

Sacroiliac (SI) Joint Fusion

Sacroiliac joint fusion surgery helps to treat joint pain in the lower back when other conservative treatment fails 1. During this surgery, neurosurgeons use a bone graft to encourage bone growth over the sacroiliac joint. This fusion reduces the pain and instability of sacroiliac joint dysfunction or inflammation of the sacroiliac joint (sacroiliitis).

The sacroiliac joint (SI joint) usually located in the pelvic cavity and connects the iliac bones (pelvis) to either side of the sacrum. This joint primarily acts as a shock-absorber between the lower portion of the body and the torso. At this point, the base of the spine links with the pelvis. The sacroiliac joint usually comprises a synovial joint and the sacroiliac ligaments.

Sacroiliac dysfunction produces significant pain in the lower back, pelvic, groin, feet, and hip. Several factors such as prolonged standing, running, taking large strides, stair climbing, bearing overweight, etc. can aggravate the symptoms of sacroiliitis. This occurs due to too much motion, arthritis or inflammation of the joint, traumatic injury, infection, etc. Research measures the association of about 15-30% chronic low back pain with sacroiliac joint.

What’s the patient conditions for a Sacroiliac Joint Fusion?

Neurosurgeons recommend a patient to undergo sacroiliac joint fusion surgery when the symptoms persist for several weeks or months and do not respond to nonsurgical treatment. Many back pain specialists usually suggest patients trying nonsurgical methods for a minimum of 8 to 12 weeks before going for the surgery. The neurosurgeon will explain the benefit and risk of this operation before performing the surgery.

Patients will discuss with their neurosurgeon about their qualifications for the spinal fusion joint surgical procedure. Neurosurgeons will collect the medical history and performs a physical examination and several clinical tests such as x-ray, CT, or MRI scan for accurate diagnosis. The final step of confirmation usually done by injecting local anesthetics into the joint space through the low back, whether it reduces the pain. A reduction of 50% to 75% pain score confirms the SI joint as the pain source.

What’s the risks associated with a Sacroiliac Joint Fusion?

Complications can occur during any surgical procedure. Potential risks associated with sacroiliac joint fusion surgery include 2:

  • Infection at the surgical site
  • Delay wound healing
  • Excessive loss of blood
  • Adverse reaction with anesthesia
  • Nerve or muscle damage
  • Lung damage
  • Localized brushing or swelling
  • Formation of blood clot or hematoma
  • Allergic reaction to the implants
  • Migration, loosening, breakage or failure of the implant, etc.

How should a Patient prepare for a Sacroiliac Joint Fusion Procedure?

Preparation of sacroiliac joint fusion surgery requires trimming the hair of the patients over the surgical site and cleaning the area with antiseptics. Neurosurgeons advise patients to avoid drinking or eating any foods at least 12 hours before the surgery 3. Patients need to discuss the medication that they took and neurosurgeons suggest to stop taking some medications such as blood thinner prior to the surgery.

How does a Spinal Surgeon perform Sacroiliac Joint Fusion?

A sacroiliac joint fusion surgery usually grafts one or both sides of the sacrum to the ileum to promote bone growth across the joint. Neurosurgeons usually perform the minimally invasive procedure as the common method of sacroiliac joint fusion. The basic steps include 4:

  • The patient will lie on their stomachs on the operating table.
  • Anesthesiologists will administer general anesthesia to the patient to fall asleep so that patient may not feel any sensation.
  • Nurses will prepare the incision site and monitor the vital signs of the patient’s body such as respiration, cardiac rhythm, etc.
  • Neurosurgeons will make a small incision (about 2 to 3 centimeters) in the buttock’s side to access the ileum.
  • A small guide pin will help to access the ilium by creating a small hole. Neurosurgeons will then drill the opening to make a passage for the implants to reach the sacrum.
  • Neurosurgeon will clear the cartilage and soft tissues to place a bone graft into the bone space.
  • Neurosurgeons fix this graft by using screws, pins, or a mallet. This bone graft helps to support these bones and encourage bone growth across the joint.
  • Finally, surgeons will wash the incision site with saline solution and put back the structures such as muscles and tissues to their normal place, and suture the skin together.

How long does a Sacroiliac Joint Fusion procedure typically take?

Minimally invasive fusion surgeries require about an hour to perform. Neurosurgeons use fluoroscopic imaging to guide and implant instruments into the sacroiliac joint throughout the surgery. Complications during the operation can make the condition worse and take more time, eventually.

What does recovery from Sacroiliac Joint Fusion look like?

Recovery following a SI joint fusion surgery depends upon the severity of symptoms, the types of fusing such as instrumentation and bone grafting, etc. Most patients with minimal invasive SI joint surgery can walk the day after surgery and can sit at 1–6 weeks following surgery 5. Recovery of the patient usually involves avoiding certain activities and adopting physical therapy and rehabilitation training.


  1.       Maigne, J. Y. & Planchon, C. A. Sacroiliac joint pain after lumbar fusion. A study with anesthetic blocks. Eur. Spine J. 14, 654–658 (2005).
  2.       Abbasi, H. & Hipp, J. A. The Assessment of Fusion Following Sacroiliac Joint Fusion Surgery. Cureus 9, (2017).
  3.       Martin, C. T., Haase, L., Lender, P. A. & Polly, D. W. Minimally invasive sacroiliac joint fusion: The current evidence. Int. J. Spine Surg. 14, S20–S29 (2020).
  4.       Cummings, J. & Capobianco, R. A. Minimally invasive sacroiliac joint fusion: One-year outcomes in 18 patients. Ann. Surg. Innov. Res. 7, 13–18 (2013).
  5.       Patel, V. et al. Minimally invasive lateral transiliac sacroiliac joint fusion using 3D-printed triangular titanium implants. Med. Devices Evid. Res. 12, 203–214 (2019).

If you’re considering a Sacroiliac Joint Fusion, please consider setting up an appointment with one of the Neurosurgical Specialists at Longhorn Brain and Spine today!