Sacroiliac Joint Block and Neuroablation

Published on 10/03/2015 by admin

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Last modified 10/03/2015

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Chapter 11 Sacroiliac Joint Block and Neuroablation

The sacroiliac joint (SIJ) is the largest axial joint in the body with an average surface area of 17.5 cm2 [1]. It is a large, auricular-shaped, diarthrodial synovial joint. However, only the anterior third of the interface between the sacrum and ilium is a true synovial joint; the rest of the junction is comprised of an intricate set of ligamentous connections. If the joints become painful, they may cause pain in the low back, buttocks, abdomen, groin or legs (Figs. 11-1 and 11-2).

The primary function of the sacroiliac joint is to lend stability, which it accomplishes through the following mechanisms:

The biomechanics of the SIJ withstand a medially directed force six times greater than the lumbar spine, but only half of the torsion and 1/20 of the axial compression load.

Sacroiliac joint dysfunction

Typically, SIJ dysfunction is initially symptomatic after a minor traumatic event, such as a fall onto the buttocks or a slip while pushing a heavy object. It is then aggravated by transitional activities, such as climbing stairs, getting up from a chair, and getting out of a car. Pain in the SIJ can also be provoked by activities requiring asymmetrical loading through the lower extremities or pelvis, such as skating, gymnastics, golfing, and step aerobics.

Dreyfuss and colleagues [2] have shown that the pain referral pattern in asymptomatic volunteers consists of the following areas:

The diagnostic criteria for sacroiliac joint syndrome, as defined by the International Association for the Study of Pain (IASP), are as follows:

One of the most consistent physical findings in patients with SIJ dysfunction is point-specific tenderness over the sacral sulcus as well as the posterior sacroiliac spine.

The prevalence of SIJ pain in carefully screened patients with low back pain (LBP) is in the range of 15% to 25%. 39% of patients with SIJ dysfunction were also diagnosed [3] with an associated spinal disorder. Of these spinal disorders complicated by SIJ dysfunction, the most common are as follows:

SIJ dysfunction can stem from both intra-articular and extra-articular sources, although extra-articular sources such as enthesopathy and fractures are more common. Nociception in the SIJ can also be caused by pathologic changes affecting many different SIJ structures, such as the following:

The following factors predispose an individual to SIJ dysfunction:

The average mechanical threshold of the SIJ nociceptive unit is shown in Table 11.1.

Table 11.1 Average Mechanical Threshold of Sacroiliac Joint and Other Nociceptive Units

Nociceptive Unit Average Mechanical Threshold (g)
Sacroiliac joint 70
Lumbar facet joint 6
Anterior lumbar disc 241

SIJ treatment options are injections, nerve blocks, and denervation. A sacroiliac joint injection serves the following two purposes:

The evidence for the effectiveness of SIJ block and denervation as diagnostic and therapeutic methods for SIJ dysfunction is shown in Table 11.2.

Table 11.2 Level of Evidence for Intra-articular Injection and Neurotomy

Intra-articular injection:  
Diagnostic method Moderate evidence for diagnosis of pain from the sacroiliac joint (SIJ)
Therapeutic method Moderate evidence for short-term relief (<3 months)
Limited evidence for long-term relief
Radiofrequency neurotomy Indeterminate evidence for managing SIJ pain