Symptoms and Diagnosis of Sacroiliitis

The symptoms and signs of sacroiliitis may range from mild discomfort to severe, debilitating pain in the buttock, lower back, and thigh.¹Buchanan BK, Varacallo M. Sacroiliitis. [Updated 2022 Sept 4]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. https://www.ncbi.nlm.nih.gov/books/NBK448141/ Sacroiliitis symptoms may remain constant throughout the day or worsen with physical activities that involve excessive twisting, bending, lifting, standing, or sitting, as these activities can stress the sacroiliac (SI) joints.

Sacroiliitis is diagnosed based on a comprehensive review of the patient's symptoms, signs, and diagnostic tests.

Common Symptoms of Sacroiliitis

The common symptoms and signs of sacroiliitis may include some combination of the following:¹Buchanan BK, Varacallo M. Sacroiliitis. [Updated 2022 Sept 4]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. https://www.ncbi.nlm.nih.gov/books/NBK448141/

• Buttock pain. Pain in the buttock is the most frequently reported symptom of sacroiliitis. The pain may be dull or sharp and is predominantly felt on the same side as the affected joint.
• Lower back pain and stiffness. Pain and stiffness in the lower back is the second most common symptom of sacroiliitis.
• Lower extremity pain. Sacroiliitis can cause pain that radiates into the hip, groin, thigh, knee, and foot. The pain may be dull or sharp and can be felt on one or both sides of the body.

The pain may worsen following physical activities such as sitting, walking, running, or any activity that involves repetitive twisting or bending of the upper body. The pain may also worsen after being inactive for extended periods of time and in the morning after waking up.

Less Common Symptoms of Sacroiliitis

Less common symptoms of sacroiliitis include:

• Upper back and abdomen pain. Rarely, sacroiliitis pain may radiate to the upper back and abdomen, which is felt as a dull ache.¹Buchanan BK, Varacallo M. Sacroiliitis. [Updated 2022 Sept 4]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. https://www.ncbi.nlm.nih.gov/books/NBK448141/
• Fatigue. Some individuals may experience fatigue and/or distress due to severe or chronic SI joint pain and inflammation.¹Buchanan BK, Varacallo M. Sacroiliitis. [Updated 2022 Sept 4]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. https://www.ncbi.nlm.nih.gov/books/NBK448141/
• Fever. While rare, when sacroiliitis occurs due to an infection of the SI joint, a low-grade fever may be present.¹Buchanan BK, Varacallo M. Sacroiliitis. [Updated 2022 Sept 4]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. https://www.ncbi.nlm.nih.gov/books/NBK448141/

While these symptoms are rare, it is advisable to consult a physician who can thoroughly evaluate the health of the lower back and pelvic tissues to rule out serious conditions and accurately diagnose sacroiliitis.

Bilateral Sacroiliitis

Sacroiliitis can affect one or both sides of the body. The likelihood of sacroiliitis being one-sided compared to both depends on the condition's underlying cause. Sacroiliitis caused by injury, trauma, or mechanical stress is typically one-sided. In contrast, bilateral sacroiliitis is more likely to occur when an underlying medical condition like autoimmune disorders, inflammatory arthritis, and bowel disorders, affect both sides of the body.²Baronio M, Sadia H, Paolacci S, et al. Etiopathogenesis of sacroiliitis: implication fo r assessment and management. Korean J Pain. 2022;33(4):294-304. http://doi.org/10.3344/kjp.2020.33.4.294

Conditions that Mimic Sacroiliitis

The symptoms of signs of sacroiliitis may mimic other lower back conditions.

Common conditions with symptoms similar to sacroiliitis include:¹Buchanan BK, Varacallo M. Sacroiliitis. [Updated 2022 Sept 4]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. https://www.ncbi.nlm.nih.gov/books/NBK448141/

• Lumbar disc herniation. Lumbar disc herniation is the bulging, protruding, or rupture of a spinal disc. Common symptoms of a herniated disc include lower back pain that radiates to the leg.
• Piriformis syndrome. Piriformis syndrome occurs when the piriformis muscle in the buttock spasms and presses on the sciatic nerve. The muscle spasm can cause pain and numbness in the buttock and legs.
• Osteoarthritis. Osteoarthritis is the most common form of degenerative arthritis that affects the joints. It may cause pain and stiffness in the SI joint.

It's important to note that these conditions can coexist with sacroiliitis. A detailed evaluation and diagnostic tests by a trained physician can help determine the underlying cause of the symptoms.

Diagnosis of Sacroiliitis

Sacroiliitis is often overlooked as a source of low back or buttock pain. There's no single test that can definitively diagnose sacroiliitis.

The diagnosis typically involves a combination of physical exams, imaging tests, and blood tests. Sacroiliitis can be challenging to diagnose because of overlapping symptoms with other common sources of back pain.³Raj MA, Ampat G, Varacallo M. Sacroiliac Joint Pain. In: StatPearls. Treasure Island (FL): StatPearls Publishing; September 4, 2022.

Common steps involved in the diagnostic evaluation of sacroiliitis, include:

• Physical examination. A physical examination at the doctor's office includes clinical tests that evaluate the range of motion, muscle strength, and reflexes in the lower back and legs. Physicians typically look for signs of injury or inflammation and may also perform tests to evaluate the strength and function of the muscles surrounding the SI joint.
• Gait pattern and leg length assessment. The physician analyzes the patient's gait pattern and any differences in leg length.⁴Kiapour A, Abdelgawad AA, Goel VK, Souccar T, Terai T, Ebraheim NA. Relationship between limb length discrepancy and load distribution across the sacroiliac oint—a finite study. Journal of Orthopaedic Research.. 2012;30(10):1577-1580. http://doi.org/10.1002/jor.22119
• Review of medical history. Reviewing the medical history includes asking about the symptoms, such as when the symptoms started and what makes the symptoms worse or better. In addition, physicians discuss any history of trauma, infection, or family history of inflammatory diseases such as rheumatoid arthritis and ankylosing spondylitis.⁵Lee A, Gupta M, Boyinepally K, Stokey PJ, Ebraheim NA. Sacroiliitis: A Review on Anatomy, Diagnosis and Treatment. Advances in Orthopedics. 2022. http://doi.org/10.1155/2022/3283296
• Imaging studies. Imaging studies, such as an x-ray, magnetic resonance imaging (MRI), and computerized tomography (CT) scan, may be ordered to assess the health of the bones, joints, and soft tissue in the lower back and pelvis.

Physicians who diagnose and treat sacroiliitis include physiatrists, primary care physicians, rheumatologists (if an arthritic cause is present), and orthopedic surgeons.

Clinical Tests for Sacroiliitis

During a physical examination, physicians conduct several tests that help reproduce the patient's pain by increasing the pressure of the SI joint and surrounding muscles.

Clinical tests for Sacroiliitis include:

• Thigh thrust test. The patient lies on their back with the clinician bending the affected hip joint to 90°. Pain in the lower back and hip indicates a positive test result.⁶Nejati P. Response to comments on ‘accuracy of the diagnostic tests of sacroiliac joint dysfunction. Journal of Chiropractic Medicine. 2021;20(2):95. http://doi.org/10.1016/j.jcm.2021.03.002
• Sacral thrust test. The patient lies on their stomach with the clinician placing both hands above the tailbone and applying controlled force to the joints. Pain in the SI joint indicates a positive test result.
• Flexion, abduction, and external rotation (FABER) test. The patient lies on their back with the hip bent, and the clinician moves the patient's leg through a series of movements, including bending, extending, and rotating movements. Pain or limited motion indicates a positive test result.³Raj MA, Ampat G, Varacallo M. Sacroiliac Joint Pain. In: StatPearls. Treasure Island (FL): StatPearls Publishing; September 4, 2022.^,7Laslett M, Aprill CN, McDonald B, Young SB. Diagnosis of sacroiliac joint pain: validity of individual provocation tests and composite tests. Manual Therapy. 2005;10(3):207-218. http://doi.org/10.1016/j.math.2005.01.003

Additional clinical tests may be performed to rule out other potential underlying conditions, such as a herniated disc or piriformis syndrome.

SI Joint Block and Blood Tests for Sacroiliitis

Diagnostic testing beyond a medical history and physical exam is primarily used to rule out other potential causes of lower back and hip pain. These studies can help the physician identify structural abnormalities or degenerative changes contributing to the symptoms.

Tests may include:

• SI joint injection. An SI joint injection—also called an SI joint block—is the primary form of confirmatory diagnostic test that can help identify pain originating from the SI joint.⁸Kao MC, Chuang CW, Hung SK, Pan PT. Diagnosis and interventional pain management options for sacroiliac joint pain. Tzu Chi Medical Journal. 2019;31(4):207-210. http://doi.org/10.4103/tcmj_54_19 As with any injection technique, a small risk of bleeding and/or nerve damage may be possible with diagnostic injections.
• Blood tests. Blood tests can help identify or rule out inflammatory and/or arthritic conditions that may cause similar symptoms to sacroiliitis, and include checking for inflammation markers, such as C-reactive protein (CRP).⁹Liu TJ, Chang CC, Chen LC, Chu HY, Hsu CS, Chang ST. Relationship of HS CRP and Sacroiliac Joint Inflammation in Undifferentiated Spondyloarthritis. Open Med (Wars). 2018;13:113-118. http://doi.org/10.1515/med-2018-0018

Once sacroiliitis is diagnosed, a structured treatment is formulated. Both nonsurgical and surgical treatments are used to treat sacroiliitis.