MRI-based investigation of characteristics and outcome of knee bone marrow edema in children with juvenile idiopathic arthritis / 中华放射学杂志

ABSTRACT

Objective:To investigate the prevalence, distribution, and prognosis of knee joint bone marrow edema (BME) in children with juvenile idiopathic arthritis (JIA).Methods:From January 2017 to December 2019, 128 JIA children in the Children′s Hospital, Capital Institute of Pediatrics were analyzed retrospectively, and 136 knees were included totally. BME was evaluated and counted from eight regions according to the juvenile arthritis MRI scoring system (JAMRIS). Chi-square test, independent sample t test or Mann-Whitney U test were used to compare the clinical characteristics between BME group (36 cases) and non-BME group (92 cases). The prognosis of BME were observed. Results:BME was found in 37 of 136 knee joints (27.2%). The ages of the children in BME group and non-BME were (8±4) and (6±4) years old, and the disease duration were 9 (3, 22) and 4 (2, 18) months, respectively, both with statistically significant differences (age: t=-2.63, P=0.010; duration: Z=-5.78, P=0.013). In 23 joints (62.2%,23/37), BME occurred at multiple locations simultaneously in the knee. Locations with BME, according to the frequency of involvement from most to least, were the lateral tibial plateau with 17, the lateral weight-bearing femur with 16, the medial tibial plateau and the medial femoral condyle both with 15, the medial weight-bearing femur with 12, the lateral femoral condyle with 8, the lateral patella with 7, and the medial patella with 5. The MRI score of most of medial femoral conclyle was 1(7/15). Of the 15 BME joints with the MRI follow-up data with interval (7±3) months, BME disappeared in 10 joints, improved in 3 joints and progressed in 2 joints within 12 months after the treatments. Conclusions:There is a low incidence of BME in JIA affected knee joint. Older children and the children with long disease duration have a higher risk for BME, and more likely involved the weight-bearing surfaces of the joint. The overall prognosis is satisfactory after the standard treatments.