Follow-up of clinical and sonographic features after extracorporeal shock wave therapy in painful plantar fibromatosis

BACKGROUND: Extracorporeal shock wave therapy (ESWT) has been used as a safe alternative treatment for refractory musculoskeletal diseases, such as plantar fasciitis, Achilles tendinopathy and gluteal tendinopathy, and various forms of fibromatosis including palmar or penile fibromatosis. However, there is limited published data for clinical and sonographic features of plantar fibromatosis after ESWT. The purpose of this study was to evaluate the long-term clinical outcome of ESWT in ultrasonography-confirmed plantar fibromatosis and ultrasonographic changes of plantar fibroma after ESWT. METHODS: Medical charts of 26 patients (30 feet) with plantar fibromatosis confirmed by ultrasonography were reviewed. Finally, a total of 10 feet who underwent ESWT for “Poor” or “Fair” grade of Roles-Maudsley Score (RMS) and symptoms persisted for >6 months were included in this study. Short-term follow-up was conducted one week after ESWT and long-term follow-up time averaged 34.0 months. The Numerical Rating Scale (NRS) and RMS were collected for the evaluation of clinical features. Follow-up ultrasonography was conducted at long-term follow-up and changes of plantar fibroma was assessed. A greater than 50% reduction in the NRS and achievement of a “good” or “excellent” grade in the RMS were regarded as treatment success. Additionally, medical charts of 144 patients (168 feet) with plantar fasciitis confirmed by ultrasonography were reviewed and subsequently, 42 feet who underwent ESWT with the same protocol were included for the comparison of clinical features. RESULTS: In plantar fibromatosis, baseline NRS (6.2 ± 1.3) and RMS (3.5 ± 0.5) were significantly improved at short-term follow-up (NRS, 1.8 ± 1.0; RMS, 2.0 ± 0.8, P < .001, respectively) and long-term follow-up (NRS, 0.6 ± 1.1; RMS, 1.4 ± 0.8, P < .001, respectively). Treatment success was recorded in seven feet (70.0%) at short-term follow-up and 8 feet (80%) at long-term follow-up, which is comparable to that of the plantar fasciitis group (28 feet, 66.7%; 35 feet, 83.3%, respectively). In long-term follow-up ultrasonography, mean fibroma thickness was reduced from 4.4±1.0 to 2.6±0.8 mm (P = .003); however, length and width were not significantly changed. There were no serious adverse effects. CONCLUSION: While these are preliminary findings, and must be confirmed in a randomized placebo control study, ESWT can have a beneficial long-term effect on pain relief and functional outcomes in painful plantar fibromatosis. However, ESWT is unlikely to affect the ultrasonographic morphology of plantar fibroma, with the exception of reducing the thickness. LEVEL OF EVIDENCE: Level III, retrospective cohort study.