Sacroiliac Joint Dysfunction in Patients With Low Back Pain
Although difficult to distinguish from similarly presenting syndromes, a detailed history, appropriate physical maneuvers, imaging, and adequate response to intra-articular anesthetic can help health care providers treat this painful condition.
Guilherme Barros and Lynn McGrath are Resident Physicians and Mikhail Gelfenbeyn is an Attending Physician, all in the Department of Neurological Surgery, University of Washington in Seattle. Mikhail Gelfenbeyn is the Chief of Neurosurgery at VA Puget Sound Health Care System in Seattle. Correspondence: Guilherme Barros (gbarros@uw.edu)
Author disclosures The authors report no actual or potential conflicts of interest with regard to this article.
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Patients experiencing sacroiliac joint (SIJ) dysfunction might show symptoms that overlap with those seen in lumbar spine pathology. This article reviews diagnostic tools that assist practitioners to discern the true pain generator in patients with low back pain (LBP) and therapeutic approaches when the cause is SIJ dysfunction.
Prevalence
Most of the US population will experience LBP at some point in their lives. A 2002 National Health Interview survey found that more than one-quarter (26.4%) of 31 044 respondents had complained of LBP in the previous 3 months.1 About 74 million individuals in the US experienced LBP in the past 3 months.1 A full 10% of the US population is expected to suffer from chronic LBP, and it is estimated that 2.3% of all visits to physicians are related to LBP.1
The etiology of LBP often is unclear even after thorough clinical and radiographic evaluation because of the myriad possible mechanisms. Degenerative disc disease, facet arthropathy, ligamentous hypertrophy, muscle spasm, hip arthropathy, and SIJ dysfunction are potential pain generators and exact clinical and radiographic correlation is not always possible. Compounding this difficulty is the lack of specificity with current diagnostic techniques. For example, many patients will have disc desiccation or herniation without any LBP or radicular symptoms on radiographic studies, such as X-rays, computed tomography (CT), and magnetic resonance imaging (MRI). As such, providers of patients with diffuse radiographic abnormalities often have to identify a specific pain generator, which might not have any role in the patient’s pain.
Other tests, such as electromyographic studies, positron emission tomography (PET) scans, discography, and epidural steroid injections, can help pinpoint a specific pain generator. These tests might help determine whether the patient has a surgically treatable condition and could help predict whether a patient’s symptoms will respond to surgery.
However, the standard spine surgery workup often fails to identify an obvious pain generator in many individuals. The significant number of patients that fall into this category has prompted spine surgeons to consider other potential etiologies for LBP, and SIJ dysfunction has become a rapidly developing field of research.
Sacroiliac Joint Dysfunction
The SIJ is a bilateral, C-shaped synovial joint surrounded by a fibrous capsule and affixes the sacrum to the ilia. Several sacral ligaments and pelvic muscles support the SIJ. The L5 nerve ventral ramus and lumbosacral trunk pass anteriorly and the S1 nerve ventral ramus passes inferiorly to the joint capsule. The SIJ is innervated by the dorsal rami of L4-S3 nerve roots, transmitting nociception and temperature. Mechanisms of injury to the SIJ could arise from intra- and extra-articular etiologies, including capsular disruption, ligamentous tension, muscular inflammation, shearing, fractures, arthritis, and infection.2 Patients could develop SIJ pain spontaneously or after a traumatic event or repetitive shear.3 Risk factors for developing SIJ dysfunction include a history of lumbar fusion, scoliosis, leg length discrepancies, sustained athletic activity, pregnancy, seronegative HLA-B27 spondyloarthropathies, or gait abnormalities. Inflammation of the SIJ and surrounding structures secondary to an environmental insult in susceptible individuals is a common theme among these etiologies.2