R07 Outcome following musculoskeletal ultrasound assessment and guided steroid knee injection in ujvenile idiopathic arthritis: a prospective study

Abstract

Background: Intra-articular knee injection is a common procedure in paediatric rheumatology. However unlike adults, in children it is mostly carried out under general anaesthesia which has its own risks. Thus the effect of the intra-articular injection has to be optimal and long lasting. We undertook this study to find out whether ultrasound (US) assessment and guided intra-articular knee injections leads to a better outcome. The purpose of this study was: 1. to evaluate the outcome following US assessed and guided intra-articular steroid (IASI) knee injection in patients with juvenile idiopathic arthritis (JIA) 2. to determine whether the base demographic, clinical, laboratory and ultrasonographic findings can predict the outcome. Methods: We followed patients who fulfilled the criterion for JIA and required an IASI to knees. We recorded demographics; disease subtype. Clinical assessments included; pain, swelling and limitation of movement,classified as mild, moderate and marked. Patients underwent MSUS assessment using a MyLab70. Joint effusion and synovial hypertrophy (SH) were classified as mild, moderate and marked. Standard blood tests were performed. Under GA, US-guided IACI the was performed using Triamcinolone Hexacetonide 20-40mg. Patients were followed up every three months for two years. Statistical analysis included Kaplan Meier survival analysis and ANOVA. Study was approved by ORECNI 10/NIR01/11. Results: 112 patients underwent 158 ultrasound guided knee injections. Sixty four had oligo; 29 had poly; 14 had extended oligo; four systemic JIA and one juvenile Sp. Median disease duration six months (Range 1-145 months). Median age at injection 90 months (range 15-261 months). Kaplan Meier survival analysis, demonstrated that overall, 64% of joints remained clinically quiet at two years.There were 58 flares in 158 knees within two years. The number of flares according to type of JIA and at end of 3, 6, 12, 18 and 24 months is given in Table 1. Those with minimal SH pre injection had significantly better outcome at two years. (72% remission) compared to those with marked SH, where just 51% were in remission.There was no significant difference in flare rates between oligo and polyarticular subtypes. Concomitant steroid or methotrexate did not alter the rates of flares. Longer duration of current episode, higher ESR and CRP and lower total steroid dose were found to predict flares. Conclusion: This is the first study in paediatric rheumatology to use ultrasound guidance in all intra-articular injections. Our outcomes are significantly better than those previously published where 69% were in remission at six months compared to our 88%. Whilst another retrospective study observed 49% were still in remission after approximately two years compared to our 64%. IACI performed under US control appears to improve the outcome in JIA and MSUS informs the clinician regarding the long term outcome.