The sacroiliac joint (SIJ) serves as the mechanical junction between the pelvis and the spine. While some regard its contribution toward lumbar spine symptoms as unimportant or irrelevant, about 13% of patients with chronic low back pain can be accounted for as having symptoms originating from the SIJ, which can either be due to the joint being the direct source of pain, or due to dysfunction in the arthrokinematics of the joint (Laslett, 2008). Because the SIJ can only upwardly rotate 4 degrees and translate a maximum of 1.6 mm, Laslett (2008)states that dysfunction of the joint is less likely to occur, especially considering that no significant difference in range of motion exists between symptomatic and asymptomatic sides in patients complaining of SIJ pain.
Thus, it is more probable that pain originating in the SIJ itself occurs more often, either through instability due to ligamentous laxity or tearing of the joint capsule, which can be caused by pregnancy or trauma, or as the result ofan inflammatory condition within the joint, such as ankylosing spondylitis. Currently, the gold standard method for diagnosing SIJ involvement is a contrast enhanced intraarticular an aesthetic block guided under fluoroscopy in which a slow injection of solutions into the SIJ provokes familiar pain while administration of a small volume of local anesthesia results in 80% or more pain relief (Laslett et al., 2005).
Mechanical stress tests, on the other hand, have more questionable reliability and diagnostic accuracy as they are unlikely to specifically target and load the SIJ in isolation and may stress and provoke pain in nearby structures.Because SIJ provocation tests can often be positive in patients with lumbar disc herniations and nerve root impingement, it is important to rule out a McKenzie assessment where centralization of symptoms can occur with repeated movements and sustained positions before performing SIJ provocation tests as not to produce a false positive result. These tests include distraction, compression,thigh thrust, sacral thrust, and Gaenslen’ s test performed on both the right and left sides.
When examining the clinical utility of SIJ provocation tests in diagnosing SIJ involvement as compared to the gold standard diagnostic injection, Laslett and colleagues (2005) found that clustering tests provides the best predictive power in which at least 2/4 or 3/6 tests correlate with positive SIJ pain. When all six tests are negative for producing familiar pain, SIJ involvement for causing low back pain can successfully be ruled out.
When comparing provocation test results in patients with positive SIJ pathology as confirmed by diagnostic injection, Laslett et al. (2005) found that the distraction test had the highest positive predictive value and the thigh thrust, compression test, and sacral thrust test all improved the overalldiagnostic ability of test clustering. The Gaenslen’s tests, alternatively, did not contribute positively to test clustering and “may be omitted from the diagnostic process without compromising diagnostic confidence” (Laslett et al.,2005). Therefore, if Gaenslen’s tests are utilized, 3/6 tests must be positive,but if they are omitted, only 2/4 tests need to be positive to ensure a high likelihood ratio. Because the thigh thrust and distraction tests are most sensitive and specific respectively, these tests should be performed first. If both of these tests elicit familiar pain, the 2/4 positive test criteria is satisfied and no further testing is indicated. If, however, only one of these tests produces familiar pain, the compression test is performed next. If positive, no further testing is needed, but if negative, the sacral thrust testis performed sequentially.
While there is a lack of research regarding treatment for patients with positive SIJ pain, evidence from randomized controlled trials supports lumbopelvic stabilization exercises for improving pain and disability in postpartum women with pelvic girdle pain, an umbrella term encompassing pregnancy related pain in the symphysis pubis and sacroiliac joints (Laslett etal., 2005). This recommendation can presumptively be extrapolated toward SIJ pain stemming from other causes besides pregnancy as lumbopelvic stabilization exercises have viable potential for improving low back pain symptoms in patients that fulfill SIJ provocation test criteria.
Kristen Gasnick, SPT
Dr. Brandon Cruz DPT, PT, OCS, SCS,CSCS
Laslett, M, Aprill, CN, McDonald, B, & Young, SB. (2005) Diagnosis of Sacroiliac Joint Pain: Validity of individual provocation tests and composites of tests. Manual Therapy; 10:207-218.
Laslett, M. (2008). Evidence-Based Diagnosis and Treatment of the Painful Sacroiliac Joint. Journal of Manual and Manipulative Therapy;16(3):142-152.