Intra- and Inter-Rater Reliability of Ultrasound in Plantar Fascia Thickness Measurement

Background

Plantar fascia is a thick connective tissue on the plantar side of the foot, which provides the normal shape of the longitudinal arch. Plantar fasciitis is an inflammation on the medial tuberosity of calcaneus on the inferior side that may cause heel pain. Imaging plays an important role in the diagnosis of heel pain. Ultrasonography has been recognized as an effective imaging tool for assessing plantar fascia thickness, monitoring the effect of different interventions and guiding therapeutic interventions in patients with plantar fasciitis. Operator dependency is a major limitation for the common use of ultrasound.

Objectives

The purpose of the present study was to evaluate intra and inter-rater reliability of ultrasound in measurements of the thickness of plantar fascia in different points of plantar fascia.

Patients and Methods

Twelve healthy (without any lower extremity disorder) young (above 18) volunteers were recruited. Both heels were scanned in the sagittal plane by two raters. Subjects lied prone. Thickness of the plantar fascia was measured at the insertion point of the calcaneus, 5 and 10 mm from insertion of the calcaneus. For statistical analysis, intraclass correlation coefficients (ICC), 95% confidence intervals (CI), and linear mixed model ANOVA effects were run.

Results

Our results showed that both intra and inter-rater reliability of plantar fascia thickness, measured by ultrasound, have high reproducibility (ICC > 0.821, ICC > 0.849). The linear mixed model suggested that neither rater nor time had a significant effect on the rater’s measurements.