SNOWMASS, COLO. —Reserve an anesthetic block to diagnose sacroiliac joint syndrome for those patients having at least three positive pain-provoking tests on physical examination, Dr. Zacharia Isaac urged at a symposium sponsored by the American College of Rheumatology.
“At least three separate studies show that if a patient has two or fewer positive provocative exam maneuvers, the likelihood that their gluteal pain is due to sacroiliac joint syndrome is very low. You can avoid a lot of needless diagnostic injections of the SI joint if you examine the patient using a cohort of provocative exam maneuvers,” according to Dr. Isaac, medical director of the comprehensive spine care center at Brigham and Women's Hospital, Boston.
Sacroiliac joint syndrome (SIJS) probably accounts for about 15% of cases of low back pain, making it the third most common cause after discogenic pain and facet syndrome. These more common conditions must be considered first and rejected as likely explanations for the patient's pain before moving on to SIJS.
“The SI joint syndrome truly is a dysfunction syndrome because there really is no imaging test that's going to show you that the SI joint is the pain generator. A SPECT [single photon emission computed tomography] scan will not show you a hot SI joint. There will not be a lot of arthritis involving this joint. There will not be a bone scan or any other imaging that will confirm the diagnosis for you. You will not find erosions on MRI. This is not sacroiliitis in any way,” the physical and rehabilitation medicine specialist stressed.
SIJS is characterized by low back and buttock pain that can refer to the groin and thigh. Hip findings are unimpressive. If symptoms are present above the level of the L5 transverse process, it's unlikely the SI joint is the cause.
The syndrome often arises post trauma or intra- or post partum.
Among the pain-provocative maneuvers useful in identifying suitable candidates for the preferred method diagnostic anesthetic block are Patrick's test, in which the heel of one leg is crossed atop the opposite knee and the top knee is pressed down in an attempt to elicit pain in the sacroiliac area.
Another is Gaenslen's test: While the supine patient holds one knee and hip flexed into the abdomen, the other leg hangs over the edge of the examining table as the physician presses down on it to hyperextend the hip and produce pain in the SI joint.
Precise reproduction of the pain upon palpation of a particular spot over the sacral sulcus is another useful indicator of SIJS. Other provocative exam maneuvers include standing extension, SI joint compression, and the joint distraction test. Dr. Isaac emphasized that the diagnostic intra-articular injection of local anesthetic into the SI joint must be performed under fluoroscopic guidance. A positive test is one that results in relief of the familiar pain.
Treatment options in SIJS are limited to intra-articular corticosteroid injections and physical therapy. Radiofrequency lesioning of the innervation of the SI joint has shown promise in observational case series and is now being looked at in more formal studies, he said.
One can avoid unnecessary diagnostic injections of the SI joint by using a cohort of exam maneuvers. DR. ISAAC