Prediction of clinical response to corticosteroid or platelet-rich plasma injection in plantar fasciitis with MRI: A prospective, randomized, double-blinded study

The purpose of this study was to identify association between magnetic resonance imaging (MRI) features and clinical data at baseline and six months following platelet-rich plasma (PRP) or corticosteroid (CS; cortivazol) injection in patients with plantar fasciitis, and to identify initial MRI criteria associated with a favorable clinical response to treatment.The study was registered on ClinicalTrials.gov (NCT03857334). MRI examinations of 36 patients with plantar fasciitis lasting more than 3 months who were randomly assigned to receive ultrasound-guided PRP (PRP group, 20 patients) or CS (CS group, 18 patients) injection were quantitatively and qualitatively analyzed with respect to plantar fascia thickness, plantar fascia hyperintensity on T2-weighted STIR (HSTIR) images, calcaneal bone marrow and surrounding soft tissues. Clinical evaluation including visual analytic scale (VAS) assessment and MRI examinations were obtained before and 6 months after treatment. Good clinical response was defined as pain VAS decrease > 50% at 6 months. ROC curves with AUC measurements were used to determine cut-off points.In the whole study population, an association was found between MRI features (deep soft tissue and calcaneal bone marrow HSTIR) and pain VAS scores for the first steps of the day (P = 0.028 and P = 0.007, respectively). No significant radioclinical associations on post-treatment MRI examinations were found in either group. Initial coronal thickness of plantar fascia was associated with a good clinical response in the CS group (P < 0.01). ROC curve analysis found that 7-mm or thicker plantar aponeurosis at initial MRI was predictive of good clinical response in patients with CS treatment (Youden index = 0.6). PRP infiltrations were effective regardless of fascia thickness (73% of patients with ≤ 7 mm aponeurosis and 67% for thicker ones).Initial facia thickness (> 7 mm) is predictive of good clinical response six months after CS injection, whereas PRP injection shows effectiveness regardless of fascia thickness.