Ultrasonographic measurements of plantar fascia thickness and echogenicity in individuals with and without plantar fasciitis: Reliability and group differences

•Ultrasonography is a reliable method to measure plantar fascia thickness and echogenicity.•Compared to the healthy control subjects, the plantar fasciitis subjects showed a thicker plantar fascia with lower echogenicity.•The plantar fascia has been affected at its insertion and the other points remote from the insertion by plantar fasciitis. Imaging techniques such as ultrasonography are beneficial for diagnosis of plantar fasciitis. The purpose of this study was to investigate intra-rater reliability of plantar fascia thickness and echogenicity in subjects with and without plantar fasciitis and to compare the measurements between the two groups. Sonographic evaluation of the plantar fascia was performed in prone position in 20 subjects without plantar fasciitis and 20 subjects with plantar fasciitis. The outcome measures extracted from the ultrasound images included plantar fascia thickness at the insertion, 1 cm and 3 cm distal from the insertion and plantar fascia echogenicity. The reliability of outcome measures was estimated for both groups using absolute and relative reliability variables. The two groups were compared using analysis of variance (ANOVA). ICCs (3, 3) for intra-rater reliability of plantar fascia thickness and echogenicity were, respectively, ≥0.89 and ≥0.89 in the healthy controls and 0.87≥ and 0.90≥ in the plantar fasciitis group. The subjects with plantar fasciitis showed a thicker plantar fascia with lower echogenicity in all of measurement stations of plantar fascia compared to the healthy controls. The results of the present study indicated that ultrasonography is a reliable method to measure plantar fascia thickness and echogenicity. Furthermore, the findings showed that plantar fascia is affected not only at its insertion but also in other points remote from the insertion in patients with plantar fasciitis. These findings support the diagnostic value of ultrasonography in therapy and research of the patients with plantar fasciitis.