This is Part 1 of a series of blogs on the evidence-based examination and treatment of sacroiliac joint dysfunction.
How common is sacroiliac joint pain? Does sacroiliac joint dysfunction really even exist? Well, opinions vary. Some practitioners always look for and frequently treat sacroiliac joint dysfunction in patients with low back pain, others don’t believe in it at all, and the majority fall somewhere in between.
But, what does the research show? Do we have evidence that sacroiliac joint dysfunction even exists? Well, kind of.
According to Sembrano et al  "the SI joint is a pain-sensitive structure richly innervated by a combination of unmyelinated free nerve endings and the posterior primary rami of L2--S3. There is, however, a wide possibility of innervations, which may explain why SI joint pain can produce different and unique referral patterns." [2-10]
So, the sacroiliac joint has the potential to be symptomatic. (To learn more about pain science, you're invited to read my evidence-based blog "How Does Pain Work?")
How common is sacroiliac joint pain?
The prevalence of sacroiliac joint pain is estimated to be between 13-30% in individuals with chronic low back pain. A study by Sembrano et al  comments, “Our finding that the SI joint is a significant pain generator in 14.5% of low back pain patients is very similar to the 18.5% and 13 to 30% findings in the studies of Maigne et al  and Schwarzer et al , respectively. Both studies used diagnostic injections as a reference standard.” (All italics throughout this blog are mine.)
Note: Regarding the use of diagnostic injections as the reference standard, the injection is best performed using fluoroscopy (or CT) and contrast. Rosenberg et al  have shown that only 22% of ‘‘blind’’ injections were actually in the joint space. To further confound the issue, there is no guarantee that the injectate is limited exclusively to the sacroiliac joint and does not bleed out (extra-articular spread) and affect other structures such as the lumbar plexus, resulting in false positives.
Sembrano et al then qualifies the estimate of 13-30%:
“Our study has a number of obvious limitations, foremost of which is the lack of a formal diagnostic algorithm implemented during the period of study. Diagnostic workup was performed on the discretion of the treating spine surgeon appropriate to the clinical diagnosis, which, in turn, was based on a synthesis of all available information from the history, physical examination, and imaging studies at the time."
This requires some pause. No study to date has concluded that imaging is helpful in diagnosing sacroiliac joint dysfunction; so, we're down to the patient history and physical examination. Additionally, who or what determined that this surgeon's diagnoses were accurate? If a different spine surgeon performed the diagnostic workup, would this estimate be different? If a clinician from a different discipline was used (chiropractic, physical therapy, physiatry), would a different estimate result?
The article continues: “Another limitation is the lack of long-term follow-up to verify if patients benefited from the treatment rendered. However, this approach also introduces the confounding effect of other variables affecting treatment outcome, such as the technical skill of the surgeon, patient motivation, implants or spacers used, and surgical complications, among others. Furthermore, treatment methods such as general body conditioning, smoking cessation, weight reduction, and others may bring about perceived benefits not specific to a major pain generator site.
“Ultimately, perhaps the most important limitation of this study pertains to the accuracy of the diagnoses arrived at in each case. Although methods and modalities used were what are presently considered standard armamentarium in the investigation of LBP tempered by physician discretion, none of these could claim 100% accuracy. For example, even as discography has become widely used, its validity to this day remains controversial, in part because postdiscography surgical outcomes have been inconsistent. For epidural injections, sensitivity figures between 65% and 100%, and specificity between 71% and 95% have been quoted. However, obtaining accuracy estimates for spinal injection techniques (e.g.,facet blocks, epidural injections, and selective nerve root blocks) have been problematic primarily because there is no available gold standard that would measure presence or absence of pain to compare them against. Some statements on accuracy may be inferred from reproducibility studies (screening and confirmatory injections) and surgical outcomes. Although the former could measure false positivity and reliability, the limitations of using surgical outcomes as reference standard have already been discussed.”
What does all of that mean? It means that an estimated 13-30% of patients with chronic low back pain are suspected as having sacroiliac joint dysfunction responsible for their symptoms. However, it’s not possible to validate that estimate at this time – we simply don’t know how many truly do because there is no gold standard for diagnosis currently available.
So, in the presence of uncertainty, how can we determine whether or not the sacroiliac joint is a relevant component of a patient’s low back pain? And, what is the latest evidence-based treatment for sacroiliac joint dysfunction once established? Future blogs will discuss the best available research in guiding the examination and treatment of suspected sacroiliac joint dysfunction.
Continue on to Part 2: "Does The Sacroiliac Joint Even Move At All?".
Dr. Damon Bescia is a fellowship-trained Doctor of Physical Therapy, board certified in orthopedics and sports physical therapy, who specializes in Orthopedic Manual Physical Therapy and serves Naperville and its surrounding communities by way of his Concierge Practice, providing private one-to-one orthopedic manual physical therapy for his clients. For more information, please visit https://www.napervillemanualphysicaltherapy.com.
 Solonen KA. The sacroiliac joint in the light of anatomical, roentgenological and clinical studies. Acta Orthop Scand Suppl. 1957; 27:1--127.
 Nakagawa T. Study on the distribution of nerve filaments over the iliosacral joint and its adjacent region in the Japanese. Nippon Seikeigeka Gakkai Zasshi. 1966; 40:419--430.
 Ikeda R. Innervation of the sacroiliac joint: Macroscopical and histological studies. Nippon Ika Daigaku Zasshi. 1991; 58: 587--596.
 Grob KR, Neuhuber WL, Kissling RO. Innervation of the sacroiliac joint of the human. Z Rheumatol. 1995; 54:117--122.
 Fortin JD, Dwyer AP, West S, et al. Sacroiliac joint: pain referral maps upon applying a new injection/arthrography technique. Part I: Asymptomatic volunteers. Spine. 1994; 19:1475--1482.
 Fortin JD, Aprill CN, Ponthieux B, et al. Sacroiliac joint: pain referral maps upon applying a new injection/arthrography technique. Part II: Clinical evaluation. Spine. 1994; 19: 1483--1489.
 Fortin JD, Kissling RO, O’Connor BL, et al. Sacroiliac joint innervation and pain. Am J Orthop. 1999; 28:687--690.
 Vilensky JA, O’Connor BL, Fortin JD, et al. Histologic analysis of neural elements in the human sacroiliac joint. Spine. 2002; 27:1202--1207.
 Cohen SP, Abdi S. Lateral branch blocks as a treatment for sacroiliac joint pain: a pilot study. Reg Anesth Pain Med. 2003; 28:113--119.
 Sembrano JN, Polly Jr DW. How Often Is Low Back Pain Not Coming From the Back?. SPINE. 2008;34(1):E27-32.
 Schwarzer AC, Aprill CN, Bogduk N. The sacroiliac joint in chronic low back pain. Spine 1995;20:31–7
 Maigne JY, Aivaliklis A, Pfefer F. Results of sacroiliac joint double block and value of sacroiliac pain provocation tests in 54 patients with low back pain.Spine 1996;21:1889–92
 Rosenberg JM, Quint TJ, de Rosayro AM. Computerized tomographic localization of clinically-guided sacroiliac joint injections. Clin J Pain. 2000; 16:18--21.