Sacroiliac Joint Pain: Causes, Symptoms & Treatment

Sacroiliac Joint Pain: Causes, Symptoms, and Treatment Options

Sacroiliac joint pain is caused by inflammation or dysfunction in the joint that connects the base of the spine to the pelvis. It produces pain in the lower back, buttocks, hips, and sometimes the legs. The condition accounts for up to 25 percent of chronic low back pain cases and is frequently misdiagnosed as sciatica, a herniated disc, or hip disease.

If you have been dealing with persistent lower back pain that does not respond to standard treatments, the sacroiliac (SI) joint may be the source. This large, weight-bearing joint absorbs shock and transfers force between the upper body and the legs with every step you take. When it becomes irritated, inflamed, or unstable, the resulting pain can be debilitating.

The challenge with sacroiliac joint pain is that it mimics many other conditions. Patients often spend months or even years receiving treatment for the wrong diagnosis before identifying the SI joint as the true cause. Understanding the anatomy, recognizing the symptoms, and knowing which diagnostic tools lead to accurate answers are the first steps toward effective relief.

What Is the Sacroiliac Joint?

The sacroiliac joint sits on each side of the lower spine, where the sacrum (the triangular bone at the base of the spine) meets the ilium (the large wing-shaped bone of the pelvis). You have two SI joints, one on the left and one on the right. They are visible as small dimples on the lower back, just above the buttocks.

Unlike the hip or knee, the SI joint allows only a small amount of movement. Its primary role is structural. It transfers the weight of the torso, arms, and head to the pelvis and legs. Strong ligaments reinforce the joint and limit excessive motion. When those ligaments become damaged, stretched, or inflamed, the joint can become a significant source of chronic pain.

According to a peer-reviewed study published in Advances in Orthopedics, SI joint dysfunction accounts for up to 25 percent of all chronic lower back pain cases. Despite that prevalence, it remains one of the most commonly overlooked diagnoses in spine care.

Common Causes of Sacroiliac Joint Pain

Several factors can irritate or destabilize the SI joint. The most common causes fall into a few broad categories.

Degenerative Changes and Arthritis

Osteoarthritis is one of the leading causes of SI joint pain, particularly in adults over 50. Over time, the cartilage that lines the joint surface wears down. This exposes the underlying bone and triggers inflammation. The resulting stiffness and pain tend to worsen gradually and become more noticeable with prolonged sitting or standing.

Trauma and Injury

A fall, car accident, or direct impact to the pelvis can damage the SI joint ligaments or the joint surface itself. Even a single high-force event can shift the joint alignment and create long-lasting instability. Sports injuries from activities like running, football, and gymnastics also contribute.

Pregnancy and Postpartum Changes

During pregnancy, the body releases a hormone called relaxin that loosens the pelvic ligaments to prepare for delivery. This increased laxity can destabilize the SI joint and cause significant pain. The added weight and altered gait patterns of pregnancy place further stress on the joint. Many women experience SI joint pain during the third trimester, and for some, the pain persists long after delivery.

Prior Lumbar Spine Surgery

Patients who have undergone lumbar fusion surgery are at elevated risk for developing SI joint dysfunction. Fusing one or more segments of the lumbar spine changes the way forces are distributed across the pelvis. The SI joints absorb more stress as a result, which can accelerate degeneration and trigger new pain. Research published through the National Library of Medicine identifies post-fusion SI joint pain as a recognized and increasingly studied condition.

Leg Length Discrepancy and Gait Abnormalities

When one leg is shorter than the other, the pelvis tilts unevenly during walking and standing. This places asymmetric stress on the SI joints. Over time, the joint on the longer-leg side may become inflamed and painful. Abnormal gait patterns from hip or knee problems can produce similar effects.

Sacroiliac Joint Pain Symptoms

SI joint pain can present differently from one person to another, but several patterns are common.

Where the Pain Is Felt

The hallmark symptom of sacroiliac joint pain is a dull, aching pain in the lower back on one side. The pain typically sits below the beltline and may radiate into the buttock, hip, groin, or upper thigh. In some cases, it can travel down the back of the leg, closely mimicking the pattern of sciatica caused by lumbar nerve compression.

This overlap is a major reason for misdiagnosis. However, there is an important distinction. True sciatica from a herniated disc or spinal stenosis typically produces numbness, tingling, or weakness that follows a specific nerve path below the knee. SI joint pain rarely causes neurological symptoms like true numbness or weakness. Instead, the leg pain from SI joint dysfunction tends to be more diffuse and harder to pinpoint.

Activities That Make It Worse

Certain movements and positions commonly aggravate sacroiliac joint pain:

• Sitting for extended periods, especially on hard surfaces
• Standing up from a seated position
• Climbing stairs or walking uphill
• Rolling over in bed or lying on the affected side
• Bending forward or twisting at the waist
• Shifting weight to one leg while standing

Patients often report that the pain is worse in the morning and improves slightly with gentle movement throughout the day.

How SI Joint Pain Differs from Other Back Pain

Distinguishing SI joint dysfunction from other causes of chronic back pain is critical for effective treatment. Here are the key differences:

How Sacroiliac Joint Pain Is Diagnosed

Accurate diagnosis begins with a thorough clinical evaluation. Your pain management doctor will review your medical history, ask about the location and behavior of your pain, and perform a physical examination.

Provocative Physical Exam Tests

Several hands-on tests help identify SI joint dysfunction. Your doctor may perform a combination of these during your visit:

• FABER test (Flexion, Abduction, External Rotation): You lie on your back and place one ankle on the opposite knee while the doctor presses down on the raised knee and the opposite hip. Pain in the SI joint area suggests dysfunction.
• Compression test: The doctor applies pressure to the top of the pelvis while you lie on your side. This compresses the SI joint and reproduces pain if the joint is the source.
• Thigh thrust test: With your hip flexed to 90 degrees, the doctor pushes downward through the thigh, loading the SI joint.
• Gaenslen’s test: One leg hangs off the edge of the exam table while the other hip is flexed. This stresses both SI joints simultaneously.

When three or more of these provocative tests reproduce your typical pain, SI joint dysfunction becomes a strong clinical suspicion. However, physical exam findings alone are not definitive.

Diagnostic SI Joint Injection

The gold standard for confirming sacroiliac joint pain is a diagnostic SI joint injection. Under fluoroscopic (live X-ray) guidance, your doctor injects a small amount of local anesthetic directly into the joint. If you experience at least 75 percent pain reduction during the numbing period, the SI joint is confirmed as the pain source.

This diagnostic block is essential because imaging alone (X-ray, MRI, CT scan) often cannot identify SI joint dysfunction. Many people with significant SI joint pain show normal imaging results, and many people with visible joint changes on imaging have no symptoms at all. The injection provides a functional test that imaging cannot replicate.

Treatment Options for Sacroiliac Joint Pain

Treatment follows a stepwise approach, starting with conservative therapies and progressing to interventional procedures when needed.

Physical Therapy and Exercise

Physical therapy is typically the first line of treatment. A therapist designs a program targeting the muscles that stabilize the pelvis, including the gluteal muscles, deep core muscles, and hip rotators. Strengthening these muscle groups reduces the load on the SI joint and improves pelvic alignment.

Manual therapy techniques such as joint mobilization can also help restore normal movement patterns. For many patients with mild to moderate SI joint pain, a consistent physical therapy program provides meaningful improvement.

Medication Management

Over-the-counter nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen or naproxen can reduce inflammation and provide short-term relief. For more severe pain, your doctor may prescribe muscle relaxants or a short course of oral corticosteroids. Medications work best as a bridge therapy to support participation in physical therapy.

SI Joint Injections

When conservative measures fall short, therapeutic SI joint injections deliver a combination of local anesthetic and corticosteroid directly into the joint under image guidance. The steroid reduces inflammation within the joint, while the anesthetic provides immediate pain relief. Many patients experience weeks to months of improvement from a single injection. Pain and Spine Specialists of Idaho offers sacroiliac joint injections and denervation as part of a comprehensive treatment approach to SI joint dysfunction.

Radiofrequency Ablation (SI Joint Denervation)

For patients who respond well to diagnostic blocks but need longer-lasting relief, radiofrequency ablation targets the sensory nerves that transmit pain signals from the SI joint. The procedure uses heat from radio waves to create a lesion on the lateral branch nerves supplying the joint.

Cooled radiofrequency ablation is often preferred for SI joint denervation because it creates a larger lesion than conventional thermal RFA. This is important because the sensory nerve supply to the SI joint is more variable and diffuse than the medial branch nerves serving the facet joints. A systematic review published in Cureus found that radiofrequency ablation for SI joint pain provides clinically meaningful relief for up to 12 months in appropriately selected patients.

SI Joint Fusion

In cases of severe, treatment-resistant SI joint dysfunction (particularly when joint instability is the primary problem), minimally invasive SI joint fusion may be an option. This procedure uses small implants to stabilize the joint and promote bone growth across the joint surface.

SI joint fusion is typically considered only after conservative treatments, injections, and radiofrequency ablation have been exhausted. Pain and Spine Specialists of Idaho includes providers with specific expertise in SI joint fusion for patients who need this level of intervention.

Supportive Therapies

Additional treatments that can complement the approaches above include:

• SI joint belts: Compression belts worn around the pelvis can provide external stability and reduce pain during daily activities.
• Activity modification: Avoiding prolonged sitting, using a cushion to reduce direct pressure, and alternating between sitting and standing can minimize flare-ups.
• Ergonomic adjustments: Proper workstation setup and supportive footwear reduce asymmetric loading on the pelvis.

Why Sacroiliac Joint Pain Is Frequently Misdiagnosed

The SI joint is one of the most commonly missed pain generators in the lower back. Several factors contribute to this diagnostic challenge.

First, SI joint pain overlaps significantly with lumbar disc disease, facet joint arthritis, hip bursitis, and piriformis syndrome. A patient whose pain radiates into the buttock and thigh may receive an MRI of the lumbar spine that shows a mild disc bulge. That incidental finding can lead to treatment targeting the disc rather than the true source of pain.

Second, standard imaging rarely reveals SI joint dysfunction. An MRI may show SI joint inflammation in cases of sacroiliitis, but many cases of mechanical SI joint pain appear completely normal on imaging.

Third, not all providers routinely test for SI joint dysfunction during a physical exam. Without provocative testing, the joint is easily overlooked.

If you have been treated for lower back pain without success, asking your pain management doctor about SI joint testing may be a worthwhile next step. Proper diagnosis is the foundation of effective treatment, and a diagnostic injection can provide a clear answer.

Frequently Asked Questions

Can sacroiliac joint pain go away on its own?

Mild SI joint irritation from a temporary cause (like a minor strain or late-stage pregnancy) can resolve with rest, ice, and time. However, chronic SI joint dysfunction caused by arthritis, ligament damage, or post-surgical changes typically requires targeted treatment. Without intervention, the pain often persists or worsens.

Is sacroiliac joint pain the same as sciatica?

No. Sciatica refers to pain caused by compression or irritation of the sciatic nerve or a spinal nerve root, usually from a herniated disc or spinal stenosis. SI joint pain originates from the joint itself. However, the two conditions can produce similar leg pain patterns, which is why accurate diagnosis with provocative testing and diagnostic injections is important.

How long does it take to recover from an SI joint injection?

Most patients can resume normal activities within 24 to 48 hours after a therapeutic SI joint injection. You may notice immediate relief from the anesthetic component, followed by a few days of mild soreness before the corticosteroid takes full effect. Peak improvement typically occurs within one to two weeks.

What kind of doctor treats sacroiliac joint pain?

Interventional pain management specialists, physiatrists (physical medicine and rehabilitation doctors), and some orthopedic or spine surgeons diagnose and treat SI joint dysfunction. Board-certified pain management doctors trained in fluoroscopic-guided injections and ablation procedures are often the best-equipped providers for this condition.

Can SI joint pain come back after treatment?

Yes. Treatments like injections and radiofrequency ablation manage symptoms but do not permanently cure the underlying joint problem. Injections may need to be repeated every few months, and radiofrequency ablation typically lasts 6 to 12 months before the nerves regenerate. For patients with persistent instability, SI joint fusion provides a more lasting structural solution.

Does an SI joint belt actually help?

For many patients, an SI joint compression belt provides noticeable relief during daily activities. The belt stabilizes the pelvis externally and reduces the micro-movements that trigger pain. It works best as a complement to physical therapy and medical treatment rather than as a standalone solution.

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This article is for informational purposes only and does not constitute medical advice. Consult a qualified pain management specialist for diagnosis and treatment recommendations specific to your situation. To schedule a consultation with a board-certified interventional pain physician, contact Pain and Spine Specialists of Idaho.