Background: Because ultrasound measurement of plantar fascia thickness is widely used in the diagnosis and evaluation of plantar fasciitis, it is important to understand and minimize the errors that occur with this measurement. The aim of this systematic review was to identify and synthesize studies reporting on intrarater and interrater reliability of ultrasound measurement of plantar fascia thickness.
Methods: After comprehensive searches in the MEDLINE, Embase, and Cochrane Library databases, 11 studies involving 238 healthy participants and 68 patients with pathologic foot disorders were included.
Results: Seven of 11 studies revealed a low risk of bias. Most of the studies reported good to excellent intrarater and interrater reliability for ultrasound measurement of plantar fascia thickness (intrarater intraclass correlation coefficient [ICC], 0.77-0.98; interrater ICC, 0.76-0.98). In addition, two studies on intrarater reliability and one study on interrater reliability showed moderate reliability (ICCs, 0.65, 0.67, and 0.59, respectively). Overall, the standard error of measurement was less than 5% and did not exceed 7%.
Conclusions: The findings of this review suggest that ultrasound measurement of plantar fascia thickness is reliable in terms of both relative and absolute reliability. Reliability can be optimized by using the average of multiple measurements and an experienced operator.