Introduction Down’s Arthropathy (DA) was first reported in the literature in 1984. Crude estimates suggest higher incidence and prevalence rates of DA compared with Juvenile Idiopathic Arthritis (JIA), (JIA prevalence 1/1000, estimated DA prevalence 8.7/ 1000). Despite this fact, there remains a paucity of data on this condition. DA is rarely recognised at onset, and remains underdiagnosed. As a direct consequence children with DA are presenting with significant joint damage and disability at diagnosis.

Objectives Perform a musculoskeletal examination on children with Trisomy 21 (T21) aged 0–20 years

Methods Children with T21 were invited to attend a screening clinic. Screening involved completion of a health questionnaire and a comprehensive musculoskeletal examination. DA cases detected were investigated and managed as per normal clinical practice. Data on a convenience sample of 33 newly diagnosed children with JIA was collected to create a comparison group.

Results 503 children with T21 have been screened for DA, 22 new cases have been diagnosed. In total, we now have 33 children attending our centre with DA (combining cases attending pre-dating the start of the study). This suggests the point prevalence of DA in Ireland is 18–21/1000. The majority of children presented with a polyarticular pattern of disease. 88% of the DA cohort had small joint involvement of the hands, significantly higher than that observed in the JIA comparison group. Erosive changes were reported on X-Ray in 29.2% of the DA cohort (9.5% in the JIA Cohort). Methotrexate-associated nausea was a significant barrier to treatment with this DMARD in DA. There was a significant delay in diagnosis of DA, 1.7 years v 0.7 years in the JIA cohort.

Conclusion Children with T21 are at increased risk of developing arthritis. There is a lack of awareness of this risk among health care professionals and the general public at large. This almost certainly contributes to poor recognition of the disease and a delay in diagnosis. The predominant pattern of disease is polyarticular small joint arthritis. Treatment with standard protocols used in JIA is complicated by drug-associated side effects in children with T21. Our study has raised a number of questions. Future research to accurately define this disease and identify best practice with regards to treatment would be invaluable. We advocate that all children with T21 should have annual musculoskeletal examination as part of their health surveillance programme.