Relationship of Body Mass Index, Ankle Dorsiflexion, and Foot Pronation on Plantar Fascia Thickness in Healthy, Asymptomatic Subjects

Abstract

BACKGROUND: We sought to investigate the thickness of plantar fascia, measured by means of ultrasonographic evaluation in healthy, asymptomatic subjects, and its relationship to body mass index, ankle joint dorsiflexion range of motion, and foot pronation in static stance. METHODS: One hundred two feet of 51 healthy volunteers were examined. Sonographic evaluation with a 10-MHz linear array transducer was performed 1 and 2 cm distal to its insertion. Physical examination was also performed to assess body mass index, ankle joint dorsiflexion, and degree of foot pronation in static stance. Both examinations were performed in a blinded manner. RESULTS: Body mass index showed moderate correlation with plantar fascia thickness at the 1- and 2-cm locations. Ankle dorsiflexion range of motion showed no correlation at either location. Foot pronation showed an inverse correlation with plantar fascia thickness at the 2-cm location and no correlation at the 1-cm location. CONCLUSION: Body mass index and foot supination at the subtalar joint are related to increased thickness at the plantar fascia in healthy, asymptomatic subjects. Although the changes in thickness were small compared with those in patients with symptomatic plantar fasciitis, they could play a role in the mechanical properties of plantar fascia and in the development of plantar fasciitis.