Biomechanical Factors Associated with Plantar Fasciitis in Non-obese Patients

The purpose of this study was to identify the biomechanical factors that correlate with plantar fasciitis in non-obese patients whose body mass index were below 25 kg/m2. The subjects were non-obese patients who were diagnosed as plantar fasciitis by clinical appearance, physical examination, and ultrasonographic findings (n=48), and non-obese control persons without clinical diagnosis of plantar fasciitis (n=30). The two groups were compared on fat pad thickness, ankle dorsiflexion range of motion (ROM), resting calcaneal stance position (RCSP), incidence of calcaneal spur, and calcaneal pitch. The results showed that, there were statistically significant differences between two groups in ankle dorsiflexion ROM, RCSP, and calcaneal pitch (p＜0.05). Multiple logistic regression analysis showed ankle dorsiflexion ROM and RCSP strongly correlated with presence of plantar fasciitis as independent predictors (p ＜0.05). In conclusion, reduced ankle dorsiflexion ROM and negative RCSP (valgus tendency in rear foot) may be the biomechanical factors associated with plantar fasciitis in non-obese patients.