Chronic inflammatory arthritis of the ankle/hindfoot/midfoot complex in children with extreme obesity.

BACKGROUND

Childhood obesity is an increasing public health concern, but little is known about how obesity contributes to chronic arthritis.

OBJECTIVE

The objective of this study was to identify and characterize children and adolescents who present with isolated arthritis of the ankle/hindfoot/midfoot complex and profound obesity.

METHODS

We identified all patients with juvenile idiopathic arthritis who underwent fluoroscopic-guided injections of the feet and ankles between July 2009 and June 2012. We determined their disease category as well as clinical, demographic, and serological features. We also identified patients who had body mass indices (BMIs) that were outliers.

RESULTS

Eighty-two patients received fluoroscopic-guided foot and ankle injections during the study period. Twenty-one percent of these patients were obese (BMI ≥95th percentile), and 33% were overweight or obese (BMI ≥85th percentile). We identified 5 of these patients who had isolated arthritis of the ankle/hindfoot/midfoot complex. All patients with isolated foot and ankle arthritis were significantly obese with BMI 98th to 99th percentile for age, and 3 had BMIs that were outliers from the broader population. These patients were also distinctive as being significantly older, more likely to be male, and less likely to have positive antinuclear antibody titers than other patients with ankle/hindfoot/midfoot complex arthritis. Finally, all 5 patients were negative for known laboratory markers associated with juvenile idiopathic arthritis.

CONCLUSIONS

We have identified a subgroup of children with chronic inflammatory arthritis limited to their ankle/hindfoot/midfoot complex and significant obesity. This study suggests that there may be interplay between obesity, inflammation, and otherwise unexplained arthritis and highlights a previously unrecognized complication of childhood obesity.