Background: Plantar fasciitis (PF) affects 7% to 10% of the population. The long-term prognosis is unknown.
Purpose: Our study had 4 aims: (1) to assess the long-term prognosis of PF, (2) to evaluate whether baseline characteristics (sex, body mass index, age, smoking status, physical work, exercise-induced symptoms, bilateral heel pain, fascia thickness, and presence of a heel spur) could predict long-term outcomes, (3) to assess the long-term ultrasound (US) development in the fascia, and (4) to assess whether US-guided corticosteroid injections induce atrophy of the heel fat pad.
Study design: Cohort study; Level of evidence, 3.
Methods: From 2001 to 2011 (baseline), 269 patients were diagnosed with PF based on symptoms and US. At follow-up (2016), all patients were invited to an interview regarding their medical history and for clinical and US re-examinations. Kaplan-Meier survival estimates were used to estimate the long-term prognosis, and a multiple Cox regression analysis was used for the prediction model.
Results: In all, 174 patients (91 women, 83 men) participated in the study. All were interviewed, and 137 underwent a US examination. The mean follow-up was 9.7 years from the onset of symptoms and 8.9 years from baseline. At follow-up, 54% of patients were asymptomatic (mean duration of symptoms, 725 days), and 46% still had symptoms. The risk of having PF was 80.5% after 1 year, 50.0% after 5 years, 45.6% after 10 years, and 44.0% after 15 years from the onset of symptoms. The risk was significantly greater for women (P < .01) and patients with bilateral pain (P < .01). Fascia thickness decreased significantly in both the asymptomatic and symptomatic groups (P < .01) from 6.9 mm and 6.7 mm, respectively, to 4.3 mm in both groups. Fascia thickness (P = .49) and presence of a heel spur (P = .88) at baseline had no impact on prognosis. At follow-up, fascia thickness and echogenicity had normalized in only 24% of the asymptomatic group. The mean fat pad thickness was 9.0 mm in patients who had received a US-guided corticosteroid injection and 9.4 mm in those who had not been given an injection (P = .66).
Conclusion: The risk of having PF in this study was 45.6% at a mean 10 years after the onset of symptoms. The asymptomatic patients had PF for a mean 725 days. The prognosis was significantly worse for women and patients with bilateral pain. Fascia thickness decreased over time regardless of symptoms and had no impact on prognosis, and neither did the presence of a heel spur. Only 24% of asymptomatic patients had a normal fascia on US at long-term follow-up. A US-guided corticosteroid injection did not cause atrophy of the heel fat pad. Our observational study did not allow us to determine the efficacy of different treatment strategies.
Keywords: corticosteroid; heel fat pad; heel spur; human; long-term prognosis; plantar fasciitis; plantar heel pain; prognosis; ultrasound.