When mentioning flat feet, we should first understand the foot arch. When standing upright, it is generally believed that the entire weight of the human body rests on the two feet, but in fact, it rests on the "arch bridge" structure of the two feet. The so-called "arch bridge" is the foot arch, a curved structure of the foot bones that curves upward. The foot arch causes a semi-circular indentation in the footprints left by barefoot walking on wet ground. There are two longitudinal arches on the inner and outer sides of the foot, with the inner longitudinal arch being 1 time higher than the outer one. When the two feet are close together, there is also a transverse arch that spans the soles of the feet. The foot arch is composed of several curved foot bones, which are connected by ligaments of different lengths and strengths and foot bottom muscles. The calf muscles, when contracted, can support the foot arch like a "hammock", playing a significant role in maintaining the foot arch. The ligaments of the foot arch have a certain elasticity, and the tightness of the ligaments determines the elasticity of the foot arch. The elasticity of the foot arch can buffer the impact force from the ground during walking and jumping, reducing the shock to the joints and brain. When the foot arch is normal, the walking gait is that the heel first touches the ground, then the sole is flat on the ground, and finally the toes leave the ground. The ligaments and muscles of the sole are not continuously stressed, but take turns to work, with a brief rest in between, so they are not easily fatigued or injured.
The footprints of normal people have a gap due to the foot arch, but people with flat feet do not have this gap. The collapse or disappearance of the foot arch is called flat feet. People with flat feet walk with the entire sole touching the ground, which can lead to ligament and muscle strain or injury in the foot. The reduction or disappearance of the elasticity of the foot arch can lead to an inability to run farther or jump higher, and the leg, foot joints, and lower back are constantly subjected to impact from the ground. The blood vessels and nerves of the foot sole cannot be protected by the foot arch and are subject to compression, resulting in soreness in the lower limbs, lower back, and foot sole after even short distances of walking. The formation of flat feet is due to congenital underdevelopment of the foot bones, muscles, and ligaments that make up the foot arch, long-term standing, excessive weight-bearing, or fracture injuries, and certain diseases such as poliomyelitis are also causes of flat feet.
For foot arch collapse caused by fatigue, most can recover after rest and foot muscle exercise. For patients with flat feet caused by congenital factors, correction should begin in childhood, such as wearing orthopedic shoes or foot arch inserts, frequently practicing flexion of the toes, or using the toes to grasp objects; walking with the heels, toes, and outer edge of the foot, shifting the weight to the outer side of the foot; and rolling a wooden stick with the sole of the foot, etc.