Symptoms & Diagnosis   Symptoms Diagnostic Tests The painful sacroiliac joint most commonly manifests itself as an aching, intermittent type pain in the low back, buttock and upper thigh. It can sometimes radiate to the groin or down the leg to the knee. In some patients it reaches down the leg past the knee into the calf or all the way to the foot. Sitting typically makes the pain worse. Holding any prolonged position, however, such as sitting or standing can exacerbate the discomfort. Shifting positions sometimes helps relieves the pain Physical exam - most of the objective diagnostic tests are useful for ruling out other causes for your low back pain. Blood work can help find an infection or inflammatory problem such as ankylosing spondylitis. X-rays are usually normal although they may show some arithmetic changes. SIJ Arthrogram/Block     Physical Examination The physical exam for sacroiliac joint pain is actually more useful for ruling out other causes -- such as a herniated disc, which is fairly easy to find with a good examination -- for the pain.  There are a number of useful tests that stress the joint and may reproduce the typical tenderness such as Patrick's Test, Gaenslen's Test, Yeoman's Test, and the Posterior Provocation Test (see inserts), but none of them is absolutely diagnostic. SIJ Arthrogram/Block The one test that has proven to be consistently worthwhile in making the diagnosis of SIJ arthrosis is the fluoroscopically guided arthrogram followed by a CAT scan. We accomplish this by bringing the patient to the fluoroscopy suite, placing a needle into the joint and injecting dye into the joint. The fluoroscope is a plain x-ray mounted on a moveable arm so that we can position it during the examination to be sure that we have placed the needle properly.  If the dye escapes or extravasates from the joint, we know that the capsule around the joint is torn which in younger patients is indicative of SIJ problems.  Along with the dye we inject an anesthetic block much like the dentist uses to numb your mouth so that he can work on a tooth.  If your pain disappears or is significantly improved, there is a very high likelihood that the SIJ is the source of your pain.  We follow that with a CAT scan to check for bony abnormality.