Ultrasonographic evaluation of changes in the joint before and after intra-articular injection in children with juvenile idiopathic arthritis.

Objective: The aim of this study is to ultrasonographically (US) evaluate the course of the knee joint in oligoarticular juvenile idiopathic arthritis (JIA) patients who received intra-articular steroid (IAS) application to the knee joint.

Methods: 237 knee joints of 175 patients with oligoarticular JIA were evaluated retrospectively. The patients were divided into two groups: those who received only IAS therapy and those who were methotrexate to IAS therapy. Synovial fluid grade changes, synovial proliferation in B mode examination and power Doppler (PD) changes were evaluated with musculoskeletal ultrasonography (MSUS) separately for each joint before the treatment and at the 2^nd, 6^th and 12^th weeks of the treatment.

Results: The percentages of regression in synovial fluid grade at the second, sixth, and 12^th weeks were respectively 73.4%, 88.6%, and 89.0% (n=174, 210, 211, respectively). Meanwhile, the percentages of regression in PD grade were 69.2%, 82.7%, and 84.0% (n=164, 196, 199, respectively). At the second, sixth and 12^th weeks, the percentage of those with synovial fluid grade 0 was 24.1%, 54.9%, 73.4%, respectively (n=57, 130, 174, respectively), while the percentage of those with PD grade 0 was 39.7%, 67.9%, 80.6%, respectively (n=94,161,191, respectively). The percentage of those without synovial proliferation in the second, sixth and 12^th weeks was found to be 26.2%, 54.9%, 73.8% respectively (n=62, 130, 175, respectively). The mean time to regression of synovial fluid, synovial proliferation, and PD in the only IAS group was significantly short. The percentage of synovitis regression was higher in the only IAS group at all weeks. This difference was especially more pronounced in the early period. When the 12^th-week results were evaluated, there was no difference between the two groups.

Conclusion: This study highlights the utility of MSUS in evaluating the early results of IAS therapy applied to the knee joint in oligoarticular JIA patients.