Sacroiliac Joint Block


A sacroiliac (SI) joint injection — also called a sacroiliac joint block — is primarily used either to diagnose or treat low back pain and/or sciatica symptoms associated with sacroiliac joint dysfunction.


The sacroiliac joints lie next to the spine and connect the sacrum (large triangular bone at the base of the spine) with the hip on both sides. There are two sacroiliac joints, one on the right and one on the left. Joint inflammation and/or dysfunction in this area can cause pain.

Why Have A Sacroiliac Joint Injection?

A sacroiliac joint injection may be given to diagnose the source of a patient’s pain, and to provide therapeutic pain relief. At times, these are separated and a patient will undergo a purely diagnostic or therapeutic injection, however two injections are always done at the one time.


A diagnostic SI joint injection is used to confirm a suspected diagnosis of sacroiliac joint dysfunction. This is done by numbing the sacroiliac joint with local anesthetic. The injection is performed under fluoroscopy (X-ray guidance) for accuracy. Once the needle has entered the sacroiliac joint, contrast is injected into the joint to ensure proper needle placement and proper spread of medication. The numbing medication is then injected into the joint.


After the numbing medication is injected, the patient is asked to try and reproduce the pain by performing normally painful activities. If the patient experiences 75-80% pain relief for the normal duration of the anesthetic, a tentative diagnosis of SI joint dysfunction is made. A second diagnostic sacroiliac injection will be performed using a different numbing medication (time release cortisone) in order to confirm the diagnosis.


If this second diagnostic injection also provides 75-80% pain relief for the duration of the anesthetic, there is a reasonable degree of medical certainty the sacroiliac joint is the source of the patient’s pain.

Pain Relief

A therapeutic SI joint injection is done to provide relief of the pain associated with sacroiliac joint dysfunction. The injection is performed using the same technique as a diagnostic SI joint injection, except that anti-inflammatory medication (corticosteroid) is included in the injection to provide pain relief by reducing inflammation within the joint.


If the patient experiences prolonged pain relief after a therapeutic sacroiliac joint injection, he or she can begin a physical therapy and rehabilitation program to further reduce pain and return the patient to normal activity levels.


If the therapeutic sacroiliac joint injection is successful in reducing or eliminating the patient’s pain for a longer duration, it may be repeated up to three times per year, in conjunction with physical therapy and rehabilitation program, to help the patient maintain normal function.

The Sacroiliac Joint Injection Procedure

The Sacroiliac Joint injection procedure is usually performed in an operating room or a dedicated procedure room. The entire procedure usually takes only minutes, and the you go home the same day.

Sacroiliac Joint Injection Side Effects and Risks

Following the injection, you will usually stay for 30 minutes to ensure there are no immediate complications or adverse reactions, such as allergic reaction or leg weakness/numbness. The doctor or other team member will determine when it is safe for you to go home.


Following a diagnostic or combination diagnostic/therapeutic sacroiliac joint injection, your pain level is assessed by you performing activities that would usually provoke pain. The percentage of pain relief is documented in a pain chart for a period of two weeks, and a physical examination is performed. A positive response is defined as at least 75 percent improvement of your painful activity related symptoms. If a second diagnostic injection is positive, then the sacroiliac joint is considered the likely source of your painful symptoms.


Although individual recommendations may differ, depending on your situation and the physician’s preference, the following are typical:


  • Drink plenty of water to help flush the dye used for fluoroscopy out of the body.
  • Do not perform excessive activities on the day of the procedure, especially if sedation was administered.
  • A list of signs or symptoms that warrant immediate medical attention will often be provided to you as a part of the discharge procedure.

Possible Risks Of Sacroiliac Joint Injection

Risks related to this procedure tend to be relatively minor and occur infrequently. Typical risks include:


  • Risks related to the medications used in the injection, such as a possible allergic reaction to a medication.
  • Bruising and/or soreness at the injection site.
  • Infection at the injection site, deeper tissues, or in the joint.


  1. Patel, AR. (2017). Sacroiliac Joint Injection. [online] Spine-health. Available at: treatment/injections/sacroiliac-jointinjection [Accessed 15 Jun. 2017]

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Please note the contents contained in this Patient Fact Sheet are not intended as a substitute for your own independent health professional’s advice, diagnosis or treatment. At Metro Pain Group, we assess every patient’s condition individually. As leaders in pain intervention, we aim to provide advanced, innovative, and evidence-based treatments tailored to suit each patient. As such, recommended treatments and their outcomes will vary from patient to patient. If you would like to find out whether our treatments are suitable for your specific condition, please speak to one of our doctors at the time of your consultation.

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