Long-term effect and prognostic factors of a low-dose radiotherapy of painful plantar calcaneal spurs : A retrospective unicenter study.

ABSTRACT

PURPOSE: To estimate the long-term effect of low-dose radiotherapy of painful plantar calcaneal spurs, and to verify possible prognostic factors. PATIENTS AND METHODS: In this retrospective unicenter study, electronic patient files of patients with painful plantar calcaneal spurs treated with low-dose radiotherapy between July 2009 and February 2020 were reviewed. The low-dose radiotherapy consisted of a total dose of 3.0 Gy given with a fraction dose of 0.5 Gy three times a week. The pain reduction was estimated using a patient questionnaire with a visual analogue scale. Kaplan-Meier statistics and Cox regression analysis were used for the statistical analysis. RESULTS: Altogether, 864 heels of 666 patients were reviewed. The probability of an insufficient pain control 10 years after low-dose radiotherapy was 45.9% (95% confidence interval 39.4-52.4%) in the subset of patients with a minimum follow-up of 3 months (582 heels of 467 patients). Patients with an unsatisfactory pain reduction 3 months after low-dose radiotherapy were offered a re-irradiation. Forty percent of the patients who received a re-irradiation developed good pain reduction. Occurrence of an initial aggravation of pain during or within 3 months after low-dose radiotherapy (p = 0.005), and treatment of bilateral painful plantar calcaneal spurs (p = 0.008) were identified as significant unfavorable prognostic factors on univariate analysis. On multivariate analysis, the initial aggravation of pain remained as independent significant prognostic factor (p = 0.01). No clear radiation toxicity was observed. CONCLUSIONS: Low-dose radiotherapy is a safe and effective treatment option for patients with painful plantar calcaneal spurs. An initial aggravation of pain during or within 3 months after radiotherapy was identified as unfavorable prognostic factor for the treatment outcome. Re-irradiation of patients with an unsatisfactory pain reduction after low-dose radiotherapy is effective and should be offered to patients.