What is Sacroilitis and How to Treat It
Definition
Sacroiliitis is inflammation of the sacroiliac (SI) joints, characterized by MRI findings consistent with sacroiliitis along with clinical examination findings (e.g., pain with direct palpation of the SI joints) and/or patient-reported symptoms of inflammatory back pain. 1 The condition accounts for up to 25% of lower back pain cases and most commonly occurs in patients with enthesitis-related arthritis, psoriatic arthritis, or undifferentiated arthritis. 2, 3
The diagnosis requires both imaging confirmation (MRI is the modality of choice) and clinical correlation—imaging findings alone are insufficient without corresponding symptoms or examination findings. 1, 4
Treatment Algorithm
First-Line: NSAIDs
Start with scheduled NSAIDs at optimal anti-inflammatory doses as initial therapy for active sacroiliitis. 5 NSAIDs provide both analgesic effects and anti-inflammatory benefits in controlling sacroiliac joint inflammation. 5
- Evaluate treatment response after 2-4 weeks of optimal dosing 5
- NSAIDs should be used at scheduled intervals rather than as-needed to maintain anti-inflammatory effect 5
Second-Line: TNF Inhibitor Therapy
For patients with active sacroiliitis despite NSAID treatment, adding a TNF inhibitor (TNFi) is strongly recommended over continued NSAID monotherapy. 5 This represents the most important escalation step based on both pediatric data and adult spondyloarthritis randomized controlled trials. 5
Common TNF inhibitors used include:
- Etanercept
- Adalimumab
- Infliximab
- Golimumab 5
Critical distinction: Methotrexate monotherapy is strongly recommended AGAINST for sacroiliitis treatment. 5 However, methotrexate may be useful as adjunct therapy for patients with concomitant peripheral polyarthritis or to prevent anti-drug antibody formation against monoclonal TNFi. 5
Alternative Second-Line Options
Sulfasalazine is conditionally recommended only for patients who have contraindications to TNFi or have failed more than one TNFi. 5 This is clearly a second-choice option when TNF inhibitors cannot be used.
Adjunctive Therapies
Glucocorticoids
Bridging therapy with a limited course of oral glucocorticoids (<3 months) is conditionally recommended during initiation or escalation of therapy, particularly in settings of high disease activity, limited mobility, or significant symptoms. 5, 6 The duration should be the shortest possible, using the lowest dose needed to control symptoms while awaiting onset of action of DMARD or biologic therapy. 1
Intraarticular glucocorticoid injections of the sacroiliac joints are conditionally recommended as adjunct therapy. 5 When performing intraarticular injections in any joint, triamcinolone hexacetonide is strongly recommended over triamcinolone acetonide. 1
Critical pitfall: Prolonged oral glucocorticoids should NOT be used as monotherapy—they are only for short-term bridging (<3 months). 6, 7
Physical Therapy
Physical therapy is conditionally recommended for patients with sacroiliitis who have or are at risk for functional limitations. 5, 6 The focus should be on maintaining range of motion and strengthening periarticular muscles. 5, 7
Treatment Escalation Pathway
The evidence-based algorithm follows this sequence:
- Start NSAIDs at optimal anti-inflammatory doses 5
- Evaluate at 2-4 weeks for adequate response 5
- Add TNF inhibitor if inadequate response to NSAIDs 5
- Consider sulfasalazine only if TNFi contraindicated or failed >1 TNFi 5
- Use bridging glucocorticoids (<3 months) during escalation if high disease activity 5, 6
- Add physical therapy for functional limitations 5, 6
Key Clinical Considerations
Regular assessment of treatment response is essential to guide therapeutic decisions. 5 The goal is prompt treatment initiation to reduce pain, stiffness, and prevent long-term joint damage. 5
Important nuance: While these recommendations are primarily derived from juvenile idiopathic arthritis guidelines 1, the treatment principles apply broadly to sacroiliitis regardless of age, as the pathophysiology and treatment response patterns are similar across spondyloarthropathies. 5, 2
Diagnostic confirmation: MRI remains the imaging modality of choice for suspected sacroiliitis, though radiography and CT (especially low-dose CT) are reasonable alternatives when MRI is unavailable. 4 Fluoroscopy-guided diagnostic joint block with anesthetic is considered the gold standard for confirming SI joint as the pain source. 2
For refractory cases not responding to medical management, interventional options include radiofrequency ablation of sacral lateral branches and SI joint fusion surgery, though these should only be considered after exhausting medical therapies. 2, 8