I’ve had years of low back and sacroiliac joint pain. My doctor has suggested an operation to fuse the SI joint. He says less motion means less pain. It seems like a serious step to take. How can I know for sure it will work?

There’s no way to be 100 percent certain about the source of painful symptoms. This is true for pain in the low back or the sacroiliac (SI) joint.

Clinical tests to provoke the SI joint offer useful information. The doctor may palpate or press on the SI and nearby structures. Putting the hip and leg in various positions and applying pressure can also help pinpoint the source of the problem.

One of the best tests is an injection of a numbing agent into the joint. Pain relief within 15 to 45 minutes is a positive sign that the SI joint is the cause of your symptoms.

Even with this test, researchers advise trying it two or three times to be sure. You should get at least 75 percent reduction of pain each time the joint is injected.

According to a recent study from Johns Hopkins University, SI fusion is safe and effective when done on the right patients. The key is to conduct all tests necessary including the joint injections.