Flatfoot refers to a series of deformities such as low arch, soft tissue laxity of the foot, and heel exostosis due to various causes. However, not all flat feet have clinical symptoms, and if they do, it is 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 have normal feet without painful deformities, but due to age, 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 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: 1. Initial stage: after long time standing or walking, the foot is easily fatigued, sore and uncomfortable, swelling can occur, which is relieved after rest. The arch of the foot is low and flat, and the heel bone is turned out. When mild symptoms appear in the early stage, 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. 2.Middle term: spasticity period. The main manifestation is spasm of peroneal muscle, foot valgus, abduction, dorsal extension position, and restricted activity. 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, conservative treatment must be performed immediately, and in serious cases, plaster or brace fixation is carried out, and if conservative treatment is not effective, surgical treatment should be taken, and the surgical method is decided after the assessment of the specific situation of the foot. 3.Late stage: ankylosis stage. The foot is fixed in valgus, abduction and dorsal extension position with or without pain, and the foot is obviously stiff (bony ankylosis). In the late stage of the disease, the arch of the foot is completely collapsed, no elasticity, bone and joint deformation, obvious ankylosis, severe pain, and osteoarthritis, at which time 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.