P09 Juvenile osteochondritis dissecans in juvenile idiopathic arthritis: a case series review.

Background Juvenile osteochondritis dissecans (JOCD) is a condition of bone and cartilage lesions. Contributory factors may include ischaemia, trauma, genetic or biomechanical factors such as abnormal joint loading. Children and young people (CYP) with juvenile idiopathic arthritis (JIA) have low physical activity levels, present with joint abnormalities and are exposed to immunosuppression including steroids which may cause reduced bone density. Here we describe JOCD in CYP with JIA in our service. Methods Retrospective reviews of case notes were conducted for current CYP with JIA in our service with known JOCD, detailing: JIA diagnosis Age & BMI at diagnosis Symptom duration pre-diagnosis Management (including steroids) JOCD diagnosis Age & BMI at diagnosis Imaging Management Results Table 1 summarises the results. Twelve (n = 10 female) CYP in our cohort of 270 had JOCD with 20 lesions diagnosed on magnetic resonance imaging (MRI). Polyarticular (n = 4) and extended oligoarticular (n = 5) were the commonest JIA sub-types with all CYP receiving systemic therapy and 75% (n = 9) requiring more than one biologic. Mean symptom duration before JIA diagnosis was 6 months (range: 1-24 months) with a mean age of 6.5 years (range: 1.5-13 years). Mean time to JOCD diagnosis was 5.5 years (range: 1.5-10.25 years) with a mean age of 12 years (range: 8-17 years) and 7 CYP having a high BMI (>85^th percentile for age). The mean number of previous steroid injections per JOCD joint was 4 (range: 0-17) compared with 3 (range: 0-8) in the non-JOCD joint. Talar dome lesions (n = 9) were commonest, followed by femoral condyle (n = 4 medial, n = 3 lateral). Initial management was conservative, with half (n = 10) requiring surgery. P09 Table 1     P09 Table 1     Conclusion This review identifies that 4% (n = 12/270) of our CYP with JIA have known JOCD, compared with 0.03% (n = 29/100,000) of the general population. Risk factors appear to be polyarticular disease, exposure to ≥ 4 steroid injections per joint, biologic-resistant disease and high BMI with low physical activity. Where CYP with JIA report symptoms which do not fit an inflammatory pattern there should be a low threshold to consider JOCD, with prospective research needed to better understand the relationship between JOCD and JIA. Conflicts of Interest The authors declare no conflicts of interest. [ABSTRACT FROM AUTHOR]