That Low Back Pain Might Actually Be Your SI Joint—Here's Why Getting the Right Diagnosis Matters

That nagging low back pain near your pelvis might not be coming from your spine at all. The sacroiliac (SI) joint, where your spine connects to your hip bones, causes up to 30% of low back pain cases, yet many people end up getting treated for lumbar spine or hip problems when the real culprit is SI joint dysfunction.

What Makes SI Joint Pain Different From Regular Back Pain?

The sacroiliac joint acts like a shock absorber between your spine and pelvis. When it doesn't move properly—either too much or too little—you develop lasting joint pain that can feel confusing because of where it's located.

SI joint pain typically shows up as low back pain below the L5 area, often radiating into your buttocks, hips, groin, or upper legs. Unlike nerve-related spine issues, SI joint pain usually stays in a specific spot you can point to with one finger and rarely causes numbness or tingling.

How Do Doctors Actually Diagnose SI Joint Problems?

Getting the right diagnosis starts with recognizing specific pain patterns. Your doctor will ask about activities that make your pain worse, then perform provocative tests that stress the SI joint in controlled ways.

Common diagnostic tests include:

• FABER Test: Checking how your hip and SI joint move together during specific positions
• Compression Test: Applying pressure to see if it reproduces your typical pain
• Thigh Thrust Test: Testing joint stability through targeted movements
• Gaenslen Test: Evaluating joint function through specific positioning

If three or more of these tests reproduce your usual pain, it often points to SI joint dysfunction as the source of your low back pain rather than a spine problem.

Why Do So Many People Get the Wrong Treatment?

The location of SI joint pain creates diagnostic confusion. Since the joint sits where your spine connects to your pelvis and hip bones, symptoms can overlap with other conditions. This leads to people spending time, money, and energy on treatments that don't address the real problem.

Your preparation for the appointment matters enormously. Doctors need to hear if your pain increases with prolonged sitting, climbing stairs, standing on one leg, or staying in one position too long. Activities that load one side of your pelvis—like stepping up or shifting weight to one leg—can quickly trigger SI joint symptoms.

Sometimes imaging tests like X-rays, CT scans, or magnetic resonance imaging (MRI) can help rule out other problems, but they don't always prove SI joint dysfunction. For confirmation, doctors may recommend diagnostic SI joint injections using local anesthetic. If you get clear pain relief right after the injection, it supports the SI joint as your pain source.

What Treatment Options Actually Work?

Most people start with conservative treatment that aims to reduce inflammation and improve how the SI joint moves and supports your pelvis. Physical therapy forms the foundation, focusing on specific exercises that stabilize the joint.

Treatment typically includes stretching tight muscles like the piriformis, hamstrings, and glutes, plus strengthening exercises for your core, abdominals, and lower body so your pelvis acts like a steady shock absorber. Many patients also use over-the-counter anti-inflammatory medications like ibuprofen or naproxen to reduce inflammation.

A sacroiliac belt can provide support by limiting painful motion between the bones of the joint. If conservative treatment doesn't provide enough relief, doctors may discuss SI joint injections with corticosteroid medication and local anesthetic to reduce inflammation and provide longer-lasting pain relief.