Pronated feet, commonly referred to as flat feet, describe a condition where the arches on the inside of the feet appear flattened, causing the entire sole of the foot to make contact with the ground when standing. It involves an inward rolling motion of the foot as weight is applied, during both standing and walking.
Understanding Foot Pronation
Pronation is a natural movement of the foot during the gait cycle, acting as a shock absorber when the foot strikes the ground. However, when this inward roll becomes excessive, it is termed overpronation. Overpronation means the arch flattens excessively, and the ankle may roll inward. This excessive motion can alter the biomechanics of the entire lower limb, leading to issues up the kinetic chain.
Structural and Inherited Factors
The underlying structure of an individual’s foot can predispose them to pronated feet. Some people are born with naturally low or absent arches, an inherited characteristic. This inherited foot type means bones and soft tissues provide less arch support. For example, variations in talus (ankle bone) or calcaneus (heel bone) alignment can influence how the foot bears weight and maintains its arch.
Generalized joint laxity, also known as hypermobility, can contribute. Individuals with lax ligaments may have more flexible foot ligaments, reducing their ability to maintain the arch. This increased flexibility allows the foot to flatten more easily under weight. Inherited bone structure and ligamentous support form a fundamental basis for pronation.
Muscular and Ligament Imbalances
The dynamic support system of the foot, muscles and ligaments, plays an important role in maintaining the arch. The posterior tibialis muscle, in the lower leg, is important for arch support. Weakness or dysfunction of this muscle can lead to arch collapse, known as posterior tibial tendon dysfunction (PTTD). Tight calf muscles, specifically the gastrocnemius and soleus, can also indirectly contribute to overpronation.
Tight calf muscles limit the ankle’s ability to dorsiflex, forcing the foot to overpronate during gait. Ligaments provide passive support to the arch. Laxity or injury to these ligaments, such as the plantar fascia or spring ligament, can compromise the arch, allowing it to flatten. These muscular and ligamentous factors work with the skeletal structure to either maintain or diminish the foot’s arch.
Lifestyle and External Influences
External factors and daily habits can worsen pronated feet. Wearing unsupportive footwear, such as inadequate arch support, can exacerbate arch flattening over time. Prolonged standing or walking, especially on hard surfaces, places continuous stress on the foot’s supportive structures. This sustained load can fatigue muscles and stretch ligaments, leading to gradual arch collapse.
High-impact activities like running or jumping increase forces on the feet, potentially overwhelming their natural shock absorption. Excess body weight places increased stress on the arches and supporting muscles and ligaments. Past foot or ankle injuries, such as sprains or fractures, can alter foot biomechanics, leading to compensatory pronation as the body adapts.
Underlying Health Conditions and Age
Certain medical conditions can cause or worsen pronated feet. Inflammatory conditions like rheumatoid arthritis can lead to joint and ligament damage in the foot, causing arch collapse. Diabetes can result in neuropathy (nerve damage) and Charcot arthropathy, causing progressive joint destruction and deformity. Pregnancy often causes temporary foot changes due to hormonal changes, such as relaxin, and increased body weight.
Aging also contributes to pronated feet. Over time, foot and lower leg muscles can weaken, and arch-supporting ligaments may lose elasticity. This age-related degeneration, coupled with wear and tear, can lead to gradual arch flattening. These physiological changes make older individuals more susceptible to developing increased symptoms.