Role of shear wave elastography in the diagnostic evaluation of plantar fasciitis: a prospective case-control study.

Objectives: To assess the advantage of the addition of shear wave elastography (SWE) to gray-scale sonography in the diagnosis of plantar fasciitis.

Methods: 30 subjects between 18-60 years of age with unilateral heel pain who were clinically suspected of having plantar fasciitis were included in this study. Their affected feet were taken as cases; while their contralateral feet served as controls. On gray-scale ultrasound, the thickness of plantar fascia, its echopattern, presence of hypoechoic areas, and perifasicular collections were recorded. SWE was done by placing seven ROIs within the plantar fascia; and the mean of their Young's modulus was taken in kPa.

Results: Plantar fascial thickening more than 4 mm had 70% sensitivity and 66.7% specificity, echopattern had 90% sensitivity and 96.7% specificity, hypoechoic areas had 80% sensitivity and 96.7% specificity, and perifascial edema had 26.7% sensitivity and 100% specificity for diagnosing plantar fasciitis. Using the ROC curve, the cut-off value of Young's modulus for the diagnosis of plantar fasciitis was found to be ≤ 99.286 kPa. This predicted plantar fasciitis with 97% sensitivity and 100% specificity. The primary diagnostic feature of ultrasound of plantar fascia thickness more than 4 mm detected 21 out of 30 cases of plantar fasciitis; whereas elastography detected an additional 8 cases which would have been missed on B-mode ultrasound alone.

Conclusions: SWE is a useful supplement and improves the diagnostic accuracy of gray-scale ultrasound in plantar fasciitis.