Flatfoot refers to a series of deformities such as low arch, soft tissue laxity of the foot and heel exostosis due to various reasons. However, not all flat feet have clinical symptoms, and if they do, they are called flatfoot syndrome. There are many causes of flatfoot, and clinically flatfoot is often divided into two categories: congenital flatfoot and acquired flatfoot, so not all flatfoot is congenital. Congenital flatfoot: congenital flatfoot often shows obvious symptoms and deformities after birth or during rapid growth and increased weight-bearing activities. Early detection is very important and should be followed by aggressive examination and treatment to identify the cause and prevent possible irreversible changes in the bone and joint. Acquired flatfoot: due to age, weight gain, or trauma, neurovascular muscle lesions, resulting in a decrease in the strength of the foot muscles or muscle imbalance, ligaments gradually relaxed, the arch of the foot collapsed to form flatfoot, known as acquired flatfoot. The mechanism of its formation is very complicated, but at present, it is thought to be mainly related to the injury of the posterior tibial tendon. Why are middle-aged and elderly people prone to flat feet? Many middle-aged and elderly people originally had normal feet without painful deformities, but due to aging, weight gain, or trauma or neuromuscular lesions, the muscle strength of the foot decreases or the muscle strength is unbalanced, the ligaments gradually relax, and the arch of the foot collapses to form a flat foot. In this case, it is called acquired flatfoot, and the mechanism of its formation is very complicated. If symptoms appear, it must be treated under the guidance of a specialist. Clinical manifestations and treatment of flatfoot: Initial stage: after standing or walking for a long time, the foot is easily fatigued, sore and uncomfortable, and swelling may appear, which is relieved after rest. The arch of the foot is low and flat, and the heel bone is turned out. In the early stage when mild symptoms appear, conservative treatment can be carried out under the guidance of a specialist, including rest, physical therapy, massage, functional exercise of the foot muscles, and wearing orthopedic shoes to prevent further aggravation of deformity and symptoms. Middle stage: spastic stage. The main manifestation is spasm of the peroneal muscle, foot valgus, abduction, dorsal extension position, and restricted movement. The medial talus is obviously sunken and prominent. The pain is aggravated and cannot be relieved after rest. In the middle stage of the lesion, the deformity and symptoms are obviously aggravated and muscle spasm appears, which must be immediately treated conservatively, and in serious cases, cast or brace fixation is carried out. If the conservative treatment is not effective, surgical treatment should be adopted, and the surgical method is decided after the assessment of the specific situation of the foot. Late stage: tonic stage. The foot is fixed in the valgus, abductor, and dorsal extension positions with or without pain and significant stiffness of the foot (bony ankylosis). In the advanced stage of the disease, the arch of the foot is completely collapsed, inelastic, with bone and joint deformation, marked ankylosis, severe pain, and osteoarthritis, at which point surgical treatment is required to relieve pain and restore limb function. It can be seen that early and middle flatfoot does not need surgical treatment. However, accurate and appropriate arch correction is necessary, and brace correction with the help of professional foot and ankle surgeons and foot and ankle brace technicians is the key to prevent early and mid-stage flatfoot from developing into a serious condition.