It’s often difficult to diagnose sacroiliac (SI) joint dysfunction, especially since the main symptom is low back pain.

In fact, SI joint dysfunction occurs more frequently than many doctors realize. And sometimes it is difficult to differentiate from low back pain and hip pain.

There are various exams and tests that can help determine whether you have SI joint dysfunction.

Usually, the first step to diagnose SI joint dysfunction is through a physical exam. During the exam, your doctor will ask you about your medical history and determine whether you have any underlying conditions that could be causing your pain.

As part of your physical exam, there are some simple tests your doctor can do to help identify the source of your pain. Some of these tests put pressure on your sacroiliac joints, which may signal that there’s a problem in that area.

For example, your doctor may perform the Flexion Abduction External Rotation (FABER) test to determine whether your SI joints are the source of your pain. This quick test is done by lying down on your back. The doctor will ask you to do specific movements (like flexing, rotating, and extending your hips) to see if your pain originates from your SI joints.

Other tests your doctor may perform:

• Fortin finger test (pointing to exactly where it hurts)
• pushing on a part of your body called the posterior superior iliac spine to see if it re-creates your pain
• pelvic gaping test
• pelvic compression test
• sacral thrust test
• thigh thrust test
• Gaenslen’s test (used to detect musculoskeletal abnormalities)

In addition to these tests, it is important to test for hip problems (so your doctor can rule them out). Your doctor will examine your hip range of motion and perform a special test called the CAM impingement test.

Ruling out other causes of back pain (other than SI joint pain) can be a bit more difficult. Your doctor will need evidence that shows clear signs of reflex changes, muscle weakness, and tension. In addition, your doctor may perform rotation and extension tests to rule out facet joint pain.

If your doctor is still not sure what’s causing your pain after your physical exam and specialized tests, then he or she may order additional tests.

• X-rays: Your doctor may order an x-ray of your pelvis, hips, or lumbar spine (low back) to help determine the cause of your pain.
• CT scans: These can give your doctor a detailed view of your joints and bones.
• MRI scans: These can provide your doctor with a close look at your soft tissues (such as your muscles and ligaments) and can show if there is inflammation in your SI joints.
• Bone scans: Your doctor may also order a bone scan if bone abnormalities are suspected. Bone scans can determine whether certain areas of your bones show signs of inflammation.
• Lab work: Your doctor may order blood work for you if he or she suspects an infection is causing your pain.

Sacroiliac Joint Injection: Another Test for SI Joint Pain
If these tests do not show signs of sacroiliac joint dysfunction, then your doctor may use an SI joint injection to diagnose your condition. Injections are one the most accurate methods of diagnosing SI joint dysfunction.

In fact, SI joint injections are considered the gold standard for diagnosing SI joint pain.

SI joint injections typically include a numbing medication (such as novocaine) and a steroid (such as cortisone) injected into the SI joint. If the injection alleviates your pain right away (at least 50% of your pain), then this tells your doctor that the SI joints are most likely the source of your pain.

These injections are typically done with the help of an x-ray to make sure that the injection is going into your SI joints.

However, if the SI joint injection does not provide pain relief, then it is important to look for other sources of pain using more advanced tests, such as hip injections and nerve root blocks

If one of these tests determines you have SI joint dysfunction, then you should know that there are multiple ways to treat this condition—from physical therapy to exercise.