Decreased cartilage thickness in juvenile idiopathic arthritis assessed by ultrasonography.

OBJECTIVE: Juvenile idiopathic arthritis (JIA) may result in disability, which is caused primarily by degeneration of the osteocartilaginous structures, due to the synovial inflammatory process. It is essential to closely monitor structural damage during the disease course. We aimed to compare ultrasound (US) measurements of joint cartilage thickness in 5 joints in children with JIA to our findings in an age- and sex-related healthy cohort regarding disease duration, joint activity, JIA subtype, age, and sex.
METHODS: We clinically examined joint activity in 95 patients with JIA and collected parent and physician global assessments. Joint cartilage thickness was assessed by greyscale US in knee, ankle, wrist, metacarpophalangeal, and proximal interphalangeal (PIP) joints. Measurements were compared to reference values of a healthy cohort from a previous study. Medical records were reviewed for JIA subtype, treatment, and disease duration.
RESULTS: Joint cartilage thickness was decreased in the knee, wrist, and second PIP joint in children with JIA compared with the healthy cohort (p < 0.001 for all). Patients with oligoarticular JIA had thicker cartilage than patients with polyarticular and systemic JIA. We also found decreased joint cartilage thickness in joints not previously affected by arthritis in children with JIA compared to the same joint in the healthy cohort. We found decreasing cartilage thickness with age and thicker cartilage in boys than in girls.
CONCLUSION: Children with JIA have reduced cartilage thickness compared with children who do not have JIA, and children with polyarticular and systemic JIA have thinner cartilage than children with oligoarticular JIA.