Sacroiliitis: Symptoms, Types, Causes and Treatment

Sacroiliitis, the inflammation of one or both sacroiliac joints, is a significant yet often under-recognized source of low back and pelvic pain. This article provides a comprehensive overview of sacroiliitis, emphasizing its symptoms, different types, underlying causes, and current treatment approaches. Drawing from multiple clinical and research sources, we aim to empower readers—patients and clinicians alike—with clear, evidence-based information.

Symptoms of Sacroiliitis

Understanding the symptoms of sacroiliitis is crucial, as they often mimic other conditions and can lead to delayed diagnosis. Patients may present with a range of clinical signs that impact daily life and mobility.

Symptom	Description	Prevalence/Note	Source(s)
Lumbogluteal Pain	Pain in lower back, buttocks, or upper legs	Most common symptom	1 2 8 13
Morning Stiffness	Stiffness upon waking, lasting >30 min	Typical in inflammatory	11 13
Fever	Elevated temperature, sometimes present	More common if infectious	1 2
Reduced Mobility	Difficulty with movement, walking, or climbing	Varies by severity	8 13
Tender SI Joint	Pain on palpation or movement of SI joint	Often detected in exam	1 6

Table 1: Key Symptoms

Lumbogluteal Pain and Stiffness

The hallmark symptom of sacroiliitis is pain, often described as deep, aching discomfort in the lower back, buttocks, hips, or even down the legs. This pain may worsen with prolonged standing, climbing stairs, or bearing weight on one leg. Inflammatory forms commonly present with morning stiffness—patients often report that their lower back feels locked or tight when they wake up, sometimes improving with activity 1 11 13.

Systemic and Localized Symptoms

In infectious sacroiliitis, fever and general malaise can accompany joint pain. Swelling or warmth over the sacroiliac joint area is less common but possible. Physical examination often reveals tenderness when pressing on the sacroiliac joint or during specific maneuvers (e.g., Patrick’s or FABER test) 1 6.

Impact on Mobility

As inflammation progresses, patients may notice reduced range of motion, limping, or difficulty performing everyday movements. In severe cases, the pain can be disabling, interfering with work and quality of life 8 13.

Types of Sacroiliitis

Sacroiliitis is not a single disease but a syndrome with various subtypes. Recognizing these distinctions is essential for accurate diagnosis and effective treatment.

Type	Main Features	Typical Triggers	Source(s)
Inflammatory	Bilateral, gradual onset, morning stiffness	Spondyloarthropathies	4 5 7 8
Infectious (ISI)	Often unilateral, acute pain, fever	Bacterial infection	1 2 6 12
Mechanical	Pain related to activity, often chronic	Overuse, degeneration	4 7 10
Degenerative	Age-related joint wear, mild chronic pain	Osteoarthritis	7 10 13

Table 2: Types of Sacroiliitis

Inflammatory Sacroiliitis

This is the classic form associated with spondyloarthropathies such as ankylosing spondylitis, psoriatic arthritis, and reactive arthritis. It often presents bilaterally and is characterized by chronic, gradually worsening pain and prominent morning stiffness. Imaging may reveal bone marrow edema, synovitis, or erosions 4 5 7 8.

Infectious Sacroiliitis (ISI)

Infectious sacroiliitis is rarer, typically acute in onset, and often presents with fever and severe unilateral pain. It is most frequently caused by bacterial infections—staphylococci being the most common pathogens. Diagnosis is often delayed due to non-specific symptoms. Imaging (MRI) and laboratory studies are key, and sometimes joint aspiration or biopsy is necessary 1 2 6 12.

Mechanical and Degenerative Sacroiliitis

Mechanical sacroiliitis results from repetitive stress, trauma, or altered biomechanics (such as after spinal fusion surgery), leading to chronic pain without significant inflammation. Degenerative sacroiliitis, meanwhile, is mostly age-related, resembling osteoarthritis of the sacroiliac joint. These forms are more common than previously recognized and often underdiagnosed 4 7 10 13.

Causes of Sacroiliitis

The causes of sacroiliitis are diverse, ranging from autoimmune diseases to infections and mechanical stresses. Understanding these etiologies is vital for tailored management.

Cause	Mechanism/Description	Notes/Examples	Source(s)
Spondyloarthropathies	Autoimmune inflammation of SI joint	Ankylosing spondylitis	5 7 8 13
Infection	Direct bacterial, TB, or brucella infection	Staph, TB, Brucella	1 2 6 12
Mechanical Stress	Overuse, trauma, post-surgery changes	Athletes, spinal fusion	4 7 10
Degeneration	Age-related cartilage wear	Osteoarthritis	7 10 13
Crystalline	Deposition of urate or calcium crystals	Gout, CPPD	2 8
Other Diseases	Paget, malignancy, sarcoidosis, etc.	Rare mimics	3 8

Table 3: Causes of Sacroiliitis

Autoimmune and Inflammatory Causes

Most commonly, sacroiliitis arises in the context of seronegative spondyloarthropathies. Ankylosing spondylitis is the prototypical example, but other related disorders—psoriatic arthritis, reactive arthritis, and inflammatory bowel disease—can also involve the sacroiliac joint. These conditions are driven by complex immune mechanisms, including genetic predisposition (e.g., HLA-B27 association) 5 7 8.

Infectious Causes

Infectious sacroiliitis, while rare, is clinically important. It can result from the spread of bacteria through the bloodstream (hematogenous), direct extension from adjacent tissues, or post-surgical infection. Staphylococcus aureus is the most common culprit, although gram-negative bacteria, tuberculosis, and Brucella species are also implicated. Prompt recognition is critical to prevent joint destruction 1 2 6 12.

Mechanical, Degenerative, and Other Causes

• Mechanical stress: Repetitive movements, pregnancy, trauma, or altered gait can cause mechanical overload of the SI joint, leading to pain and low-grade inflammation 4 10.
• Degenerative changes: Age-related cartilage breakdown leads to osteoarthritic changes in the SI joint 7 13.
• Crystalline arthritis: Deposition of uric acid (gout) or calcium pyrophosphate (CPPD) crystals can rarely cause sacroiliitis 2 8.
• Other mimics: Conditions like Paget’s disease, malignancy, and sarcoidosis can also affect the SI joint, sometimes mimicking classic sacroiliitis. Imaging and careful clinical assessment help differentiate these 3 8.

Treatment of Sacroiliitis

The treatment of sacroiliitis is tailored to its underlying cause and severity. Approaches range from conservative to invasive, with emerging modalities on the horizon.

Treatment Approach	Example/Details	Indication/Notes	Source(s)
NSAIDs	Ibuprofen, naproxen	First-line for inflammation	8 11 13
Physical Therapy	Targeted exercise, posture correction	Improves function, reduces pain	9 13
Disease-Modifying Drugs	Biologics (e.g., TNF inhibitors)	For spondyloarthropathy	5 11 13
Antibiotics	Tailored to pathogen	Infectious sacroiliitis	1 2 12
Steroid Injections	Ultrasound or CT-guided SIJ injection	For flares or persistent pain	11 13
Surgery	Debridement, fusion	Severe/refractory cases	10 12 13
Radiofrequency Ablation	Nerve ablation (minimally invasive)	Chronic pain, refractory cases	9 13

Table 4: Treatment Approaches

Conservative and Medical Management

• NSAIDs: Non-steroidal anti-inflammatory drugs are the mainstay for most inflammatory sacroiliitis, providing pain relief and reducing inflammation 8 11 13.
• Physical therapy: Structured exercise and postural training improve mobility, strengthen supporting muscles, and reduce pain 9 13.
• Disease-modifying drugs: For autoimmune-mediated cases (e.g., ankylosing spondylitis), biologic agents like TNF inhibitors or IL-17 blockers are effective in controlling inflammation and preventing progression 5 11 13.

Interventional Therapies

• Steroid injections: Image-guided corticosteroid injections into the SI joint can provide rapid and sustained pain relief, especially for active sacroiliitis or when medications alone are insufficient 11 13.
• Radiofrequency ablation: This minimally invasive technique targets nerves supplying the SI joint, and may be considered for patients with chronic, refractory pain 9 13.

Infectious Sacroiliitis Management

• Antibiotics: Prompt, targeted antibiotic therapy is essential for infectious sacroiliitis. The choice and duration depend on the identified pathogen. In some cases, prolonged courses (several weeks to months) are needed 1 2 12.
• Surgical intervention: When joint destruction is advanced or when infection does not resolve with antibiotics alone, surgical debridement or even joint fusion may be required 12.

Surgical and Advanced Options

• Surgical fusion: In chronic, refractory cases—particularly with severe structural damage or instability—minimally invasive or open surgical fusion of the SI joint may be considered 10 12 13.
• Emerging therapies: Regenerative medicine and new biologic agents are being studied for cases resistant to standard therapies 13.

Future Directions

Advances in imaging (including AI-assisted diagnostics), biologic therapies, and interventional pain management offer hope for more personalized and effective treatment in the future 13.

Conclusion

Sacroiliitis is a complex, multifaceted condition that requires a nuanced, individualized approach. Early recognition, accurate diagnosis, and tailored treatment can dramatically improve patient outcomes.

Key Points:

• Sacroiliitis most commonly presents with lower back/buttock pain, morning stiffness, and reduced mobility; fever may indicate infection.
• Types include inflammatory, infectious, mechanical, and degenerative forms; careful history and imaging help distinguish them.
• Causes range from autoimmune diseases and infections to mechanical stress and degenerative changes.
• Treatment is multifaceted: NSAIDs, physical therapy, disease-modifying agents, antibiotics, injections, and surgery may all play a role.
• Emerging diagnostic and therapeutic technologies promise continued improvement in the management of sacroiliitis.

By understanding its symptoms, subtypes, causes, and evolving treatments, patients and clinicians can work together toward better outcomes and improved quality of life.