Methotrexate use in juvenile idiopathic arthritis and its impact on growth plate development: A prospective observational cohort study

Juvenile Idiopathic Arthritis (JIA) is a chronic inflammatory disease that can disrupt normal skeletal growth in children. Methotrexate (MTX) is widely used as a disease-modifying therapy in JIA, has uncertain effects on the developing growth plate and bone elongation. Hence, we enrolled 40 children with JIA, dividing them equally into MTX-exposed and non-MTX groups and evaluated growth plate morphology (via imaging), growth velocity (using height-for-age Z-scores) and biochemical markers (IGF-1, ALP, Vitamin D) over 12 months. The MTX group showed significantly reduced growth velocity (ΔZ = 0.31 vs. 0.58, p < 0.01), more epiphyseal irregularities on MRI (35% vs. 5%) and lower IGF-1 and ALP levels compared to controls. Although no severe skeletal defects were found, these findings suggest MTX may subtly affect growth, highlighting the need for careful longitudinal monitoring in treated children.