Correlation between the outcome of extracorporeal shockwave therapy and pretreatment MRI findings for chronic plantar fasciitis

Background. The purpose of this study was to investigate the relationship between magnetic resonance imaging (MRI) findings before extracorporeal shockwave therapy (ESWT) and the treatment outcome of ESWT. Methods. This study examined 50 feet with chronic plantar fasciitis. The scores before ESWT and after a six-month follow-up were investigated using the Japanese Society for Surgery of the Foot (JSSF) Ankle-Hindfoot Scale and the Visual Analog Scale (VAS). MRI before ESWT was used for image evaluation. MRI revealed thickening of the plantar fascia (PF), and an investigation was conducted regarding the findings of a high-signal-intensity area (HSIA) inside the PF, edema near the PF, and bone marrow edema (BME) of the calcaneus. Results. The average JSSF score and VAS score improved significantly at follow-up. In total, 44 feet were noted in the improved group. MRI revealed that the average amounts of PF thickening did not significantly differ between the improved group and the non-improved group. HSIA, edema near the PF, and BME were observed in 36, 41, and 11 feet in the improved group, respectively; and 2, 4, and 2 feet in the non-improved group, respectively. Conclusions. An HSIA in the PF predicted symptom improvement more easily than other MRI findings.