Normal sonoanatomy of small joints in healthy children: changes in cartilage and vascularisation according to age and gender.

OBJECTIVES: The metacarpophalangeal (MCP) and metatarsophalangeal (MTP) joints may be involved in juvenile idiopathic arthritis. Our goal was to describe their normal sonoanatomy in healthy children, according to age and gender. METHODS: We studied 41 consecutive healthy children (20 girls, 21 boys; age 2-15 years) divided into four age groups: 2-4 years (n=9), 5-7 years (n=11), 8-12 years (n=12), and 13-15 years (n=9). Longitudinal ultrasound axis of the MCP and MTP joints were obtained. The evolution of the cartilage thickness and vascularisation of these joints were studied according to age and gender. The MCP or MTP joints were the statistical unit. RESULTS: At all sites, on B-mode images, cartilage thickness was associated with age (p<0.0001). Cartilage thickness at different sites was significantly greater in boys than in girls (p≤0.05). Blood vessels were seen within the cartilage, with differences across age groups. CONCLUSIONS: This study provides children's age- and gender-specific sonoanatomy data of MCP and MTP and confirms the importance of using colour Doppler or Power Doppler to study cartilage vascularisation.