Can Pes Planus Cause Plantar Fasciitis?
Yes, pes planus (flat feet) is an established biomechanical risk factor that can cause plantar fasciitis by creating excessive tensile strain on the plantar fascia, though the exact pathomechanical relationship remains incompletely understood. 1, 2
Biomechanical Mechanism
Pes planus creates a lowered medial longitudinal arch, which increases tensile strain within the plantar fascia and produces microscopic tears at the fascial origin on the medial tubercle of the calcaneus. 3
The flat foot deformity results in increased plantar pressures during walking and standing, particularly in the midfoot region, contributing to repetitive biomechanical stress on the plantar fascia. 4
Excessive pronation of the subtalar joint—commonly associated with pes planus—is another biomechanical pathway through which flat feet contribute to plantar fasciitis development. 1
Clinical Evidence and Caveats
Multiple studies have documented the association between pes planus and plantar fasciitis, with flat feet consistently identified as one of several anatomical deformities that predispose to this condition. 1, 2, 5
However, scientific support for the precise role of arch mechanics in plantar fasciitis development is equivocal, despite abundant anecdotal clinical evidence. This may reflect difficulty in measuring arch mechanics in vivo or suggest that tensile failure is not the sole pathomechanical feature. 3
Histological evidence reveals that chronic plantar fasciitis typically shows degenerative changes rather than active inflammation, challenging the traditional inflammatory model and suggesting alternative mechanisms (stress-shielding, vascular disturbances, metabolic factors) may also contribute. 3
Other Contributing Factors
Pes planus rarely acts alone—plantar fasciitis typically results from multiple causative factors including obesity, middle age, tight Achilles tendon, chronic diseases like diabetes, and repetitive weight-bearing activities. 1, 2, 6
The true cause may remain obscure in individual patients, and a combination of factors is often present. 2
Clinical Implications
When evaluating patients with pes planus, actively assess for early signs of plantar fasciitis including point tenderness at the medial tubercle of the calcaneus and heel pain worst with first steps after rest. 6
Offloading interventions are critical—foot deformities like pes planus require properly fitting footwear, extra-depth shoes, custom-made insoles, or orthoses to reduce plantar pressure at high-risk locations. 4
For patients with both pes planus and loss of protective sensation (such as diabetic neuropathy), the combination significantly increases ulceration risk and requires aggressive preventive footwear interventions. 4