Sacroiliac Joint Injection in Castle Rock
What is a Sacroiliac Joint Injection?
A sacroiliac (SI) joint injection delivers steroid medication and a local anesthetic directly into the sacroiliac joint - the large joint where the lower spine connects to the pelvis. Like facet joint injections, SI joint injections serve both a diagnostic and therapeutic purpose. If the injection significantly reduces your pain, it confirms that the SI joint is the source. The steroid component then provides anti-inflammatory relief that can last weeks to months.
What is the SI Joint and Why Does It Cause Pain?
The sacroiliac joints sit on either side of the lower spine, connecting the sacrum (the triangular bone at the base of the spine) to the ilium (the large pelvic bone). These joints bear a significant amount of the body's weight and absorb force during walking, running, and bending. When the SI joint becomes inflamed or develops arthritis, it can cause pain in the lower back, buttock, hip, and sometimes down the leg - a pattern that is often mistaken for sciatica or lumbar spine problems.
SI joint pain is one of the most commonly overlooked causes of low back pain. Studies suggest that the SI joint is responsible for 15 to 30% of low back pain cases. It is especially common after lumbar spine surgery, in patients with leg-length differences, and in women during or after pregnancy.
What Conditions are Treated with SI Joint Injections?
Sacroiliac joint dysfunction
Sacroiliitis (inflammation of the SI joint)
SI joint arthritis (osteoarthritis or degenerative changes)
Post-surgical SI joint pain (commonly develops after lumbar fusion)
Postpartum SI joint pain
SI joint pain from leg-length discrepancy, scoliosis, or altered gait
How is SI Joint Pain Different from Sciatica?
SI joint pain and sciatica can feel similar because both can cause pain in the lower back, buttock, and leg. However, they come from different sources. Sciatica is caused by compression or irritation of a spinal nerve root, usually from a disc herniation or stenosis. SI joint pain comes from the joint itself.
The clinical exam and your response to a diagnostic SI joint injection help distinguish between the two. If your symptoms are primarily buttock-focused, worse with prolonged sitting or transitioning from sitting to standing, and your MRI does not show a clear nerve compression, the SI joint is a likely suspect.
How Should I Prepare?
Wear loose clothing that allows access to your lower back. Blood thinners generally do not need to be stopped for SI joint injections. No fasting is required. Arrange for a ride home if you are having bilateral injections or if the team advises it.
What Happens During the Procedure?
You will lie face down on a procedure table. The skin is cleaned and numbed with a local anesthetic. Using fluoroscopy (live X-ray), a thin needle is guided into the SI joint. Contrast dye is injected to confirm the needle is inside the joint. The steroid and anesthetic mixture is then injected. The procedure takes about 5 minutes.
How Much Does It Hurt?
The injection itself takes only a few minutes. Most patients feel a brief pinch at the skin from the local anesthetic, followed by mild pressure as the needle enters the joint. Discomfort is generally rated between 2 and 4 out of 10. The SI joint is close to the surface, so the needle does not need to travel very deep.
What Should I Do After the Procedure?
Keep a pain diary for the rest of the day. Note your pain level before the injection, immediately after, and over the following hours. This helps confirm whether the SI joint is the source.
Avoid strenuous activity for 24 hours.
Resume normal activities gradually the next day.
Avoid submerging the injection site in water for two days.
When Will I Feel Better?
The local anesthetic may provide immediate temporary relief lasting a few hours. The steroid begins working within one to two days, with full effects over about a week.
How Long Does the Relief Last?
Duration varies. Many patients experience relief for two to six months. If the injection confirms the SI joint as the source but relief is short-lived, the team may recommend SI joint radiofrequency ablation for longer-lasting results, or PRP as a steroid-free alternative.
What Comes Next If the Injection Helps?
If the SI joint injection confirms the diagnosis, the next step depends on duration of relief:
Good relief lasting months: Repeat injections as needed, or consider PRP for a steroid-free approach.
Short-lived relief (confirms diagnosis but wears off quickly): SI joint radiofrequency ablation, which targets the lateral branch nerves supplying the joint and can provide 6 to 12 months or more of relief.
Minimal relief: The SI joint may not be the primary pain source, and the team will re-evaluate.
Does Insurance Cover SI Joint Injections?
Yes. Most insurance plans cover SI joint injections when documented criteria are met. Prior authorization may be required, and the team handles this in-house.
Schedule a Consultation
If you have low back or buttock pain and are unsure whether the SI joint is the source, a diagnostic injection can provide answers. Dr. Carrera's team can evaluate your symptoms and determine whether an SI joint injection is the right next step.