Research Review by Dr. Shawn Thistle©

Date:

Dec. 2006

Study Title:

Sacroiliac joint pain: Anatomy, biomechanics, diagnosis, and treatment

Authors:

Foley BS & Buschbacher RM

Publication Information:

American Journal of Physical Medicine & Rehabilitation 2006; 85: 997-1006.

Summary:

The sacroiliac joint (SIJ) is a known pain generator in the low back/pelvic region, and has traditionally been a major focus for chiropractors and other manual therapists. The literature provides a conservative estimate that 13-30% of chronic low back pain patients have the SIJ as a pain generator.

Overall however, the literature on SIJ pathology and treatment remains controversial and incomplete. Many clinical aspects of this joint need to be scientifically clarified, including clinical assessment, orthopedic testing, treatment and rehabilitation. That being said, uncomplicated SIJ problems are what many consider a “bread and butter” condition that is amenable to chiropractic spinal manipulation and other physical therapy interventions.

This paper reviews the current state of the literature about SIJ anatomy, mechanics, assessment, and treatment.

Anatomy of the Sacroiliac Joint
  • the SIJ is a diarthrodial joint that is 1-2mm wide
  • the joint surfaces are lined with hyaline cartilage (although most agree that the iliac surface is more fibrocartilaginous)
  • the inferior third of the joint has some histological characteristics of a synovial joint
  • no two people have exactly the same joint appearance
  • with age, the joint space narrows, and may become rougher and filled with debris
  • contrary to previous belief, there is no evidence that this joint fuses with age
  • there are ligaments anterior to the joint (anterior SIJ ligament), inside the joint (interosseous SIJ ligament), and on the posterior aspect of the joint (dorsal sacral ligament – which can be subdivided into superior [short] and inferior [long] sections)
  • innervation of the SIJ is still controversial – the anterior portion is likely innervated by the sacral plexus, and the posterior portion is likely innervated primarily by the L4-S1 spinal nerves, with some contribution from the superior gluteal nerve
  • gold chloride studies have confirmed the presence of mechanoreceptors (paciniform and non-paciniform types) in the periarticular tissues of the SIJ – indicating a proprioceptive and pain signaling potential from the joint
Biomechanics of the SIJ
  • no muscles directly cross the SIJ (although we should all be aware of many that can influence the joint)
  • during normal activity, joint motion is small – not exceeding 2-3 degrees in the transverse or longitudinal planes
  • during flexion of the hip, the ipsilateral ilium glides backwards and downwards, and during extension the ilium glides forward and away from the sacrum (please note that the normal amount of motion and clinical relevance has yet to be determined)
  • subjects with SIJ pain have demonstrated delayed EMG onset of multifidus and internal oblique with movements, and early activation of biceps femoris when compared to pain-free control subjects
  • the correlation between static pelvic malposition (or asymmetry) and low back pain has not been determined
Clinical Presentation & Assessment of SIJ Pathology
  • pain from the SIJ can be felt in the low back, pelvis, groin, or gluteal region
  • unilateral pain is more common than bilateral
  • athletes involved in sports requiring unilateral loading of the joint – as in kicking and throwing – are more susceptible to SIJ injury
  • a history of trauma is present in an estimated 44-58% of those with SIJ pain
  • SIJ pain is more common in pregnant women – presumably due to altered mechanics secondary to elevated relaxin concentrations, increased lumbar lordosis, altered posture, or weight gain
  • clinical tests used to assess the SIJ include (but are not limited to): joint line palpation, Gaenslen’s test, FABER test, Yeoman’s test, thigh thrust, side compression, approximation, active SLR, femoral shear tests etc.
  • the best and most valid combination of the above tests is still being investigated
  • plain film x-ray and MRI are the most useful imaging modalities for identifying sacral fractures, neoplasm, sacroiliitis, and ankylosing spondylitis
  • there is no true gold standard for diagnosing pain of SIJ origin – however most consider fluoroscopic intra-articular injection to be the best available technique
Treatment of SIJ Problems
  • joint mobilization and manipulation have not been shown to induce lasting positional changes in the SIJ – but can be effective for reducing pain
  • there is some evidence to support intra-articular corticosteroid injections – with a reasonable limit of 3 in 6 month period or 4 in one year

Conclusions & Practical Application:

This paper provides a concise review of the literature regarding the SIJ, but also highlights the glaring deficiencies in the existing literature. Clear answers with direct clinical applicability remain elusive regarding:
  • which clinical tests are most effective for implicating SIJ involvement versus other regional structures
  • which treatment methods (soft tissue, manipulative etc.) offer the best immediate and long-term relief from SIJ pain
  • if positional evaluation of the SIJ has any clinical relevance, or if it can be changed in a sustainable way with treatment
This paper was an invited review, and as such made no claim of being a comprehensive review of the literature. Both authors are medical doctors, and I got a distinct sense that they didn’t have much knowledge of manual medicine or chiropractic, and thus avoided some of the relevant literature in these areas. This was particularly evident in the section on clinical assessment, where some recent studies have begun to clarify which combinations of orthopedic tests seem most beneficial for SIJ assessment.

I do think this paper is worth reviewing as it provides a concise review of the anatomy and biomechanics of the area, and a good source of references for studies done on injection diagnostics and therapeutics.

As a seemingly common source of low back pain, the SIJ (as with many other aspects of low back and pelvic pain) requires further scientific study to gain a deeper understanding of its role in body mechanics, how pathology of this joint presents clinically, and how it can be approached from a treatment perspective.