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.