How Is Flatfoot Formed?

Flatfoot (pes planus) refers to the absence of the medial longitudinal arch in the foot. The arch is a critical structural component of the foot; its absence—particularly when associated with pain or discomfort following physical activity—is termed symptomatic flatfoot. Although flatfoot is relatively common in daily life, most individuals do not require treatment. Intervention is typically reserved for cases where flatfoot significantly impairs gait or causes functional limitations. So, how does flatfoot develop? Below is an explanation.

Causes of Flatfoot

1. Genetic Factors

Congenital flatfoot and altered weight-bearing alignment are often asymptomatic at birth. Symptoms typically emerge only when flatfoot is severe or when external factors exacerbate biomechanical stress. Over time, symptoms may progressively worsen, leading to traumatic joint changes—including reduced or lost joint mobility. In such cases, a family history of flatfoot—often involving one or both parents—is frequently observed.

2. Improper Weight-Bearing

Excessive or inappropriate mechanical loading can cause ligamentous strain and fatigue in the foot’s supporting structures, resulting in arch collapse. Examples include prolonged standing on excessively hard surfaces; premature engagement in heavy physical labor among adolescents—where body weight exceeds the arch’s load-bearing capacity; sudden participation in long-distance walking without prior conditioning; obesity or overweight; and habitual wearing of overly narrow footwear or shoes with excessively high heels—all of which predispose individuals to flatfoot development.

3. Congenital Osseous Foot Deformities

Individuals with certain congenital bony abnormalities—such as a relatively short first metatarsal, an elongated second metatarsal, or hypoplastic navicular bone—exhibit diminished muscular support and poor ligamentous stability during weight-bearing, thereby increasing susceptibility to flatfoot.

4. Poor Constitutional Health

Generalized constitutional weakness is another significant contributor to arch collapse. Chronic systemic conditions—including tuberculosis, rheumatic diseases, cardiovascular disorders, and other debilitating illnesses—may lead to nutritional myopathy and consequent muscle atrophy, as well as elongation and laxity of ligaments. Even modest weight-bearing or prolonged ambulation can thus precipitate arch flattening. Similarly, adolescents exhibiting the “constitutional developmental insufficiency syndrome”—characterized by tall, slender body habitus and generalized muscular hypotonia—have a notably high prevalence of flatfoot.

The above outlines the primary etiologies of flatfoot. We hope this information proves helpful.