Ultrasound-guided Sacroiliac Joint Injection in Patients with Established Sacroiliitis: Precise IA Injection Verified by MRI Scanning Does Not Predict Clinical Outcome

Objective: IA injections of SIJs with corticosteroids are often performed in patients suffering from low back pain due to active sacroiliitis. However, SIJ injections are technically demanding, and therefore the clinical outcome of ultrasound-guided corticosteroid SIJ injections was analysed in relation to the accuracy of the injection.

Methods: Ultrasound-guided injections were performed with 40 mg triamcinolone and 0.78 mg gadolinium in 20 SIJ of 14 consecutive patients suffering from active sacroiliitis. Immediately following SIJ injection, MRI scanning was initiated to verify the correct placement of the drug. Clinical outcome of the intervention was determined using a numerical pain rating scale (NRS) at Days 1 and 28.

Results: Despite ultrasound guidance, only 8 injections (40%) were exactly positioned into the SIJ space, whereas the other 12 injections (60%) missed the SIJ. However, there were no significant differences observed in the clinical outcome between the IA-injected group and the peri-articular-injected group. There was similar pain relief observed in both groups 24 h and 28 days following the intervention [IA injection group: mean NRS-baseline: 6.8 (range 4-9), NRS-24 h: 4.3 (range 1-7) and NRS-day 28: 3.5 (range 1-5); peri-articular injection group: mean NRS-baseline: 7.0 (range 5-10), NRS-24 h: 4.1 (range 1-10) and NRS-day 28: 4.5 (range 1-8)].

Conclusion: These results demonstrate that IA SIJ injections remain technically challenging despite ultrasound guidance. However, peri-articular deposition of triamcinolone appears sufficient for pain and symptom control in patients suffering from active sacroiliitis.