FAQ’s on Sacroiliac (SI) Joint Injections in Philadelphia

An injection into the sacroiliac (SI) joint is called an SI joint injection, sacroiliac joint block, or a SI joint block. This procedure is used for the diagnosis and treatment of low back pain in those people with suspected for having sacroiliac joint dysfunction.

Where is the SI joint?

The sacroiliac joint is located where the lower portion of the spin and back (sacrum) joints the pelvic bone (ilium). This joint has cartilage, as with all weight-bearing joints, so it is prone to pain and arthritis. The pain is usually related to degeneration. This joint is the cause low back pain in around 15-25% of patients.

Why are SI joint injections performed?

The two main reasons for sacroiliac joint injections is to diagnose the source of a person’s pain and to provide pain relief. Many times, the patient receives the benefits of both factors in one injection. During an arthritis flare up, SI injections will alleviate pain, and are used in conjunction with physical therapy, pain medication, and chiropractic treatment.

What causes inflammation of the SI joint?

Certain medical conditions cause the sacroiliac joint to become inflamed and painful. In addition, stress on the joint results in serious pain. The SI joint can be irritated due to:

  • Sacroiliitis
  • Ankylosing spondylitis
  • Rheumatoid arthritis
  • Degenerative bone disease
  • Pregnancy
  • Osteoarthritis

How do I prepare for the SI joint injection?

Before the procedure, you should discuss your medications with the doctor. Blood-thinning agents will need to be held for several days beforehand. When you arrive at the medical facility, a nurse discusses the benefits and risks of the procedure, and ask you to sign an informed consent form. After you change into a gown, the nurse places an IV catheter in your arm because sedation and fluids may be given.

How is the sacroiliac joint injection performed?

The patient is placed in the prone position (face down), and the skin along the region is sterilized with an antiseptic solution. The doctor uses a local anesthetic to numb the skin and deeper tissues before the needle is positioned into the sacroiliac joint. Fluoroscopy (x-ray guidance) is used to assure correct needle placement, using contrast dye. A corticosteroid and local anesthetic is injected into the joint. The procedure takes around 20 minutes to perform.

What happens after the sacroiliac joint procedure?

After the SI joint injection procedure, a nurse will monitor you for 20-30 minutes. Soreness at the injection site is expected, so use ice packs to relieve this discomfort. We recommend that you rest for the remainder of the day, and return to activities gradually and as tolerated.

Does the sacroiliac joint injection work?

Chronic low back pain causes intense pain and mobility problems. These injections are low-risk and minimally invasive. Studies show that SI joint injections are preferred to conventional measures, offering an 85% efficacy rate. In another study regarding sacroiliac joint injection for patients with sacroiliitis, 77% of patients reported complete pain relief.

What risks and complications are associated with the SI joint injection?

As with all minimally invasive procedures, the SI joint injection is relatively risk-free. However, rare risks include bleeding, infection, nerve injury, allergic reaction to dye or medications, and blood vessel damage.

What other treatments help with sacroiliac joint pain?

The doctor can use radiofrequency ablation to deaden the nerves of the SI joint. This involves use of electric current to destroy nerve endings that supply the joint. Also called medial and lateral blocks, they offer around 75% pain relief that lasts for 3-12 months.


Pekkafali, M.Z, Kiralp, M.Z., Basekin, C.C., Silit, E. et al. (2003). Sacroiliac Joint Injections Performed With Sonographic Guidance. Journal of Ultrasound Medicine, 22, 553-559.

Sahin O, Harman A, Akgun RC & Tuncay IC (2012). An intraarticular sacroiliac steroid injection under the guidance of computed tomography for relieving sacroiliac joint pain: A clinical outcome study with two years of follow-up. Archives of Rheumatology, 27(3): 165-173. DOI: 10.5606/tjr.2012.028