[Sacroiliitis in children with spondyloarthropathy: therapeutic effect of CT-Guided intra-articular corticosteroid injection].

Purpose: The prospective investigation of the therapeutic effect of CT-guided intra-articular corticosteroid injection into inflammatory sacroiliac (SI) joints compared to conventional treatment with nonsteroidal anti-inflammatory drugs (NSAIDS) in children with juvenile spondyloarthropathy (jSpA) and the determination of the role of dynamic magnetic resonance imaging (MRI) in establishing the indication and monitoring the therapy.
Materials and Methods: The study comprises 89 children with known jSpA who were diagnosed by MRI to have a unilateral or bilateral sacroiliitis. Therapy with NSAIDS was initiated or continued in all 89 patients. Four weeks after the diagnostic MRI, two groups were distinguished according to the clinical response to NSAIDS, with group 1 consisting of 33 responders and group 2 of 56 non-responders. The patients of group 2 were treated with CT-guided intra-articular corticosteroid injection (low-dose injection) while the therapy with NSAIDS was continued. A total of 83 SI joints were punctured without complications, 27 bilaterally and 29 unilaterally. The indication for the intervention was based on inflammatory activity as determined by MRI. The therapy was monitored by clinical follow-up every 8 to 12 weeks over a period of 20 months. Follow-up by dynamic MRI was performed in all 56 children of group 2 and in 15 of the 33 children of group 1 within 8 +/- 4 months of the initial examination.
Results: A total of 87.5% of the children in group 2 showed a statistically significant decrease in their subjective complaints from 6.9 +/- 3.4 to 1.8 +/- 1.7 (p < 0.05) as measured on a visual analog scale (VAS from 0 to 10). Improvement was seen as early as 1.5 +/- 1.0 weeks after the intervention and lasted for a mean of 12 +/- 6 months. The children in group 1 already showed similar improvement of the VAS from 6.8 +/- 3.2 to 1.5 +/- 1.4 (p < 0.05) during the initial four weeks of NSAIDS therapy, with the improvement lasting for the 20-month observation period. The follow-up dynamic MRI (0.1 mmol/kg body weight) during therapy showed a statistically significant lower contrast-enhancement in both groups (group 1: 117 +/- 43 % versus 38 +/- 24 %, p < 0.05; group 2: 127 +/- 59 % versus 38 +/- 22 %, p < 0.05). One third of the patients of group 2 showed progression of joint destruction despite absence of subjective complaints.
Conclusion: CT-guided intra-articular corticosteroid injection has proven an effective, symptomatic, and uncomplicated therapy of acute sacroiliitis in patients with jSpA. Dynamic MRI has a role in establishing the indication for intervention but its role for any follow-up is restricted to cases with inconclusive clinical response.