Sacroiliac Joint (SI joint) Injection

Sacroiliac joint block
Sacroiliac (SI) joint blocks are injections that are primarily used for diagnosing and treating the low back pain associated with sacroiliac joint dysfunction. The SI joint lies next to the spine and connects the sacrum (bottom of the spine) with the pelvis (hip).

In an SI joint block approach, a physician uses fluoroscopic guidance (live x-ray) and inserts a needle into the sacroiliac joint to inject lidocaine (a numbing agent) and a steroid (an anti-inflammatory medication). It takes a highly skilled and experienced physician to be able to insert a needle into the sacroiliac joint.

An SI joint block may be repeated up to three times per year. For the treatment to be successful, the injection should be followed by physical therapy and/or chiropractic manipulations to provide mobilization and range of motion exercises.

Anatomy

The human hip girdle is made up of three large bones joined by three relatively immobile joints. One of the bones is called the sacrum and it lies at the bottom of the lumbar spine, where it connects with the L5 vertebra. The other two bones are commonly called "hip bones" and are technically referred to as the right ilium and the left ilium. The sacrum connects with both hip bones at the sacroiliac (SI) joints.

Above is a cross-section of the human pelvis. The bottom of the this picture is the back of the person's hips (in fact, you can sort of discern the butt-crack) The top of the picture is the person's lower belly, 2-3 inches below the belly-button. The thick white ring defining the margin of the cross-section is fat, the large dark areas are mostly muscles, and the broad, V-shaped structure arcing through the middle is the pelvis. All three pelvic bones are in view: the lower one is the sacrum, attached to its upper right is the right ilium, to the upper left is the left ilium. The muscles labeled G are the gluteus muscles, I = iliopsoas muscles, R = rectus abdominus muscles (the ones that give a washboard stomach), L.I. = large intestine.
 

This procedure will take 15-30 minutes. You will remain awake throughout the test. You will be asked to lie in a prone position (face down) on a table in the fluoroscopy suite or CT scanner. Your back will be cleansed with an antiseptic (usually iodine) solution and the area will be numbed. The radiologist will use fluoroscopy (x-ray) to guide the placement of a thin needle to the SI joint. After correct needle placement is confirmed by x-rays, a small amount of local anesthetic and steroid will be injected.

Due to the effects of certain medications, your driving reflexes may be impaired. You will need someone to drive you home after the procedure. Please make the necessary arrangements.

PLEASE NOTIFY A TECHNOLOGIST IF THERE IS A CHANCE THAT YOU MAY BE PREGNANT !

FREQUENTLY ASKED QUESTIONS

Q. Are there any special preparations / restrictions?
A. Ideally, blood thinners should be stopped 48-72 hours prior to the procedure and any pain medications should be stopped 8 hours prior to the test. You should not have anything to eat or drink 6 hours prior to the procedure unless otherwise instructed by your physician. You will not be able to drive home after your procedure.

Q. How will I feel after the procedure?
A. You may experience numbness and/or relief from your symptoms for up to 6 hours after the injection. Your usual symptoms may then return and may possibly be worse than usual for a day or two.

Q. When will the pain relief medication take effect?
A. It may take 3-7 days before you will be able to feel any effects from the medication. If there is no change in your symptoms after 2 weeks, your doctor may want to investigate other possible sources for your pain.

Q. Are there any side effects?
A. Possible side effects of the steroid medications include headaches, mild fluid retention, increased blood sugar levels, hiccups, flushing, palpitations, difficulty sleeping. These side effects occur in only about 5% of patients and commonly disappear within 1-3 days after the injection.

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