Sacroiliac Joint Injection

Updated: Feb 10, 2017
  • Author: Stephen Kishner, MD, MHA; Chief Editor: Erik D Schraga, MD  more...
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Overview

Background

The sacroiliac (SI) joint can be a source of low back pain. In assessing the etiology of the low back pain, a complete history, physical examination, psychosocial evaluation, and appropriate imaging may be helpful. Various clinical tests specific to the SI joint during the physical examination have been documented in aiding the diagnosis of SI pain.

By using SI anesthetic blocks for diagnosis, the SI joint has been shown to be a source of pain in 10-27% of suspected cases of chronic low back pain. [1]  Patients with medical conditions such as goutrheumatoid arthritis, Marie-Strumpell or ankylosing spondylitispsoriasis, fracture, malignancy, congenital deformity, or infection can also develop pain in the SI joint.

Pregnant women are at risk for SI joint pain because pregnant women produce a hormone called relaxin, which causes excess motion at the SI joint. [2]  Patients with a leg length discrepancy can also develop SI joint pain. [3]  In addition, any condition that limits weightbearing (eg, history of surgery on a limb or pain in the lower extremity) may cause SI joint pain because of the uneven distribution of weightbearing during the gait cycle. [3]  Patients who have undergone prior spinal surgery may also have increased SI joint pain. [4, 1]

 Injection of the SI joint (see Technique) can be either diagnostic or therapeutic.

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Indications

Indications for SI joint injection are as follows:

  • Diagnostic - To investigate the SI joint as the etiology of lower back pain
  • Therapeutic - To treat SI joint pain (when combined with steroids)
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Contraindications

Absolute contraindications for SI joint injection include the following:

  • Patient refusal to proceed with the injection procedure
  • History of significant allergic reactions to injected solutions - Note that reported allergy to local anesthetic is typically from the preservative in multiple-use containers; anesthetics in single-use containers can generally be used without allergy
  • Local malignancy

Relative contraindications include the following:

  • Uncontrolled diabetes mellitus
  • Pregnancy
  • Systemic or local infection at the site of a planned injection
  • Bleeding disorder or fully anticoagulated blood (eg, patient taking blood thinner, multiple anti-inflammatory medications)

Patients taking anticoagulation medications have an increased bleeding time; therefore, such medications should be held for 7 days prior to the injection and for 24 hours after the injection. Patients taking anticoagulants for reasons such as stroke and heart disease should speak to the prescribing physician before holding the anticoagulation medication for the procedure.

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Technical Considerations

Anatomy

The SI articulation is an amphiarthrodial joint, formed between the auricular surfaces of the sacrum and the ilium. The articular surface of each bone is covered with a thin plate of cartilage. They are separated by a space containing a synoviumlike fluid; hence, the joint presents the characteristics of a diarthrosis. The ligaments surrounding the joint are the interosseous ligament and the anterior and posterior SI ligaments.

Motion at the joint is limited; in one analysis, rotation was a mean of 2.5° (0.8-3.9°), and joint translational movement was a mean of 0.7 mm (0.1-1.6 mm). [5]  No difference was reported in the motion between symptomatic and asymptomatic joints.

The morphologic and physiologic base for pain signals originating from the normal anterior capsular and interosseous ligaments is provided by the calcitonin gene-related peptide (CGRP) and substance P immunoreactive fibers present in these ligaments. [6]  Therefore, both extra-articular and intra-articular approaches should be considered for diagnostic infiltration for SI joint pain.

An anatomic study on adult cadavers demonstrated that the SI joint is predominantly, if not entirely, innervated by sacral dorsal rami. [7]

In 2001, Murata et al performed a study to delineate the sensory innervation in the ventral and dorsal sides of the SI joint. [8]  They reported that the dorsal innervation derives from the dorsal root ganglions of the lower lumbar and sacral levels (from L4 to S2), and the ventral innervation originates from the dorsal root ganglions of the upper lumbar, lower lumbar, and sacral levels (from L1 to S2).

The presence of nerve fibers and mechanoreceptors in the SI ligament has been demonstrated. [9]  Referral patterns based on SI joint provocation and analgesia have been published [10, 11, 12] ; however, the only pain pattern found to be associated with patients who responded to SI joint injections was groin pain. [13]

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Outcomes

As many as two thirds of patients may have significant improvement of approximately 9 months' duration with steroid injection. The pain may recur, and the injection can be repeated. [14, 15] However, systematic reviews have found the short- and long-term effectiveness of intra-articular SI injections to be poor. [16]

A double-blind study was done in 10 patients with painful sacroiliitis. [17] A total of 13 joints were injected with either steroid (n=6) or placebo (n=7). At 1 month, patients described greater than 70% pain relief in five of the six SI joints injected with corticosteroids. No pain relief was reported in the placebo-injected joints.

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