Sacroiliac joint involvement in children with inflammatory bowel diseases.

Objective: Sacroiliitis (SI), an inflammatory arthropathy, may accompany pediatric inflammatory bowel diseases (IBDs), present with non- specific back pain, hence might be unnoticed. The aims of this study were to assess the frequency of the SI in children with IBD and determine the characteristics of the association of SI with the clinical hallmarks of the IBD.

Methods: In this prospective, cross sectional study, twenty-seven children with IBD, 7-18 years of age were evaluated. Patients with low back pain or stiffness, alternating buttock pain, or hip pain were examined for the presence of SI. The radiologic manifestations on X-ray suggesting sacroilitis were confirmed with Magnetic resonance imaging (MRI).

Results: Twenty-seven children (16 girls, female/male=1.45), with mean age of 12.55±3.6 years, of which 52% had ulcerative colitis (UC), 41% had Crohn's disease (CD), and two had indeterminate colitis (IC). The median time from IBD diagnosis was 6.0 (18.0) months for patients with SI and 12.0 (13.5) months for patients without SI. Low back pain or stiffness was observed in 13 patients (48%). SI was present in eight (30%) of the children with IBD. The patients with CD were more prone to SI (45% of CD vs. 21% of UC patients). All patients with SI were negative for HLA-B27 genotyping. The disease activity and gender were not associated with increased risk for SI. MRI was remarkable for bone marrow edema in all of the patient, followed by erosions in six of them (75%), synovial enhancement observed in five (63%), and erosion associated enthesitis of the pelvic region was observed in two (25%) of the patients.

Conclusion: SI may remain obscured in children with IBD. Children with CD are more prone to SI than those with UC. Pediatric rheumatology-pediatric gastroenterology collaboration might augment screening in at-risk patients.