Background/Purpose: Down’s Arthritis (DA) is an inflammatory joint condition affecting children with Down syndrome (DS). It is 18-21 times more common than JIA in the general paediatric population (JIA prevalence 1/1000). Children with DA usually present with a poly-articular, RF negative pattern of disease, with predominance in the small joints of the hands & wrists. Despite it’s higher prevalence, a significant delay in diagnosis is frequently observed. Joint laxity & hypotonia are almost universal in children with DS, contributing to an increased risk of a number of musculoskeletal disorders & degenerative joint disease. Clinical signs & symptoms may not always help differentiate between inflammatory joint disease & joint hypermobility. We aim to report the radiological features described by a Paediatric Musculoskeletal Radiologist (PMR) when reviewing hand & wrist radiographs in a cohort of children with DA.

Methods: A retrospective review of all hand & wrist radiographs in a convenience sample of 19 children with DA was undertaken by a PMR. Bone age, carpal & metacarpal bone abnormalities were documented, as were corresponding clinical findings following musculoskeletal examination by a Paediatric Rheumatologist. Wrist MRIs were performed on 4 of the 19 children. The results of these studies were also included in our report.

Results: 18/19 children (10/19 (53%) Female; Average Age 13yrs (0.8-19yrs); 100% Full Trisomy 21 genetics) had radiographs of their hands & wrists. Bone age was below chronological age in 5 (28%) of the cohort imaged. Time to DA diagnosis from symptom onset was known in 8/19 children & on average was 1.8 years (0.14-4.9 years). Over half (63%) of the cohort were detected through a musculoskeletal screening programme offered to children with DS & not from direct referral to the Tertiary Rheumatology Centre. On musculoskeletal examination the most commonly affected joints, 95% of cases, were the PIP joints, followed by the wrists (68%), knees (58%), toes (37%) & MCP joints (32%). The average joint hypermobility score using the Beighton system was 2 (0-6).

Radiograph & MRI review highlighted a range of carpal & metacarpal bone abnormalities. The most common abnormality was crowding of the carpal bones with associated degenerative disease (63%). The earliest sign of degenerative disease was observed in a child aged 10 months whose MRI with gadolinium contrast demonstrated synovial enhancement of the proximal carpal row. The second most common finding (42%) was scalloping of the base of the first metacarpal. Other less frequent features identified (5% of cohort) included carpal pits, tuft irregularity & dactylitis. Bone erosions were evident on plain film in 50% of the cohort.

Conclusion: Radiographic carpal & metacarpal bone changes appear to be prevalent in DA & do not always correspond to clinical signs & symptoms. Undetected, these features can have a significant functional impact. If detected & managed in a timely & appropriate manner, irreversible joint damage & long-term sequelae could be avoided. These results support the importance of access to a specialist PMR & MRI. Our plan now is to compare these results with two separate cohorts; children with JIA & children with DS with no evidence of inflammatory arthritis.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/radiological-features-identified-in-the-hands-of-children-with-down-syndrome-and-inflammatory-arthritis/