The relationship between the flexible flatfoot and plantar fasciitis: ultrasonographic evaluation.

BACKGROUND The purpose of this study was to investigate the relationship between flexible flatfoot and plantar fasciitis. METHODS Twenty-three subjects with flexible flatfoot and 23 subjects with normal arched feet were enrolled. Footprint analysis was used to evaluate the foot conditions in both groups to calculate the individual arch index. We compared the sonographic images of plantar fascia in the flexible flatfoot group with the normal arch group using high-frequency ultrasound. RESULTS The analysis results indicated that the thickening of the plantar fascia in the flexible flatfoot group was significantly different from the normal arch group. In the flexible flatfoot group, 10 of 23 patients (43.4%) had plantar fasciitis, but only two subjects (8.7%) in the normal arch group had plantar fasciitis. CONCLUSIONS There was a higher incidence of plantar fasciitis in the flexible flatfoot group than the normal arch control group in this study.