Flatfoot

　　1. Abnormality of foot bones: Abnormal position and shape of the cuneiform bone, accessory cuneiform, metatarsal bones, and calcaneus;

　　2. Abnormalities of foot muscles: Abnormal insertion of the anterior tibial muscle and fibular muscle, soft intrinsic and extrinsic muscles of the foot; imbalance in the force on the foot muscles and ligaments during loading.

　　3. Genetic factors: Genetic factors play an important role in the occurrence of flatfoot, usually polygenic inheritance.

　　The early symptoms are pain in the anterior and medial malleolus, exacerbated by long-term standing or walking, relieved by rest, extrajoint swelling of the joint, the most severe at the navicular tuberosity, difficult to walk, and the Achilles tendons of both feet present in a crisscross shape.

　　The white powder stained paper and footprint examination prove that the longitudinal arch of the footprint is missing, the middle part of the sole becomes wider, sometimes the heel also becomes wider, X-ray examination shows the foot arch disappears, the angle between the longitudinal axis of the calcaneus and the longitudinal axis of the talus is large, and the bony bridge formation is shown after the age of 12.

      1. Pain
It is usually located on the medial side of the sole (posterior and medial pain of the hindfoot), and it becomes more severe after long-term standing or walking, and it often appears with progressive worsening. Occasionally, pain can also occur near the lateral malleolus of the ankle joint. This is due to the collapse of the foot arch causing the hindfoot to deviate outward, followed by the collision between the fibula and the calcaneus.
      2. Swelling
Extrajoint swelling, with the most severe at the navicular tuberosity.
      3. Abnormal gait
Pain in the affected foot and foot arch collapse can cause a decrease in running and even walking ability, abnormal gait, such as the external八字 gait.
      4. Pain and abnormal gait
It can affect other joints in the body, such as compensatory varus of the knee and compensatory external rotation of the hip due to excessive outward deviation and internal rotation of the affected foot, which may lead to pain and arthritis in the knee, hip, and lower back. Some flatfoot patients may have low back pain as the only symptom.
      5. Severe flatfoot deformity
Other joints of the foot and ankle may be involved, such as the subtalar joint and the cuneocuboid joint, with decreased flexibility or even stiffness.
      6. Flatfoot
It can be accompanied by conditions such as plantar fasciitis, talonavicular syndrome, etc.

　　Engage in functional exercises of the foot's intrinsic and extrinsic muscles, such as walking on the sole of the foot, plantar flexion exercises, and heel raise external rotation exercises. At the same time, choose shoes with good arch support and avoid prolonged standing, which are all meaningful for the prevention of flatfoot syndrome.

　　During the initial examination, have the patient stand up and inspect the overall force line relationship of the hindfoot and forefoot from the front and back of the ankle. Pay attention to the shape of the foot's longitudinal arch under the loaded condition. The foot structure may appear normal when sitting, but it will undergo significant changes after being loaded, which is common in patients with excessive flexible flatfoot deformity, flexible toe deformity, and excessive hypermobility of the metatarsophalangeal joints. From the back, it can be seen that the affected hindfoot generally presents with an outward deviation, and 'polydactyly' appears due to the abduction of the forefoot. Observe the patient's plantar flexion during the unilateral or bilateral heel raise test while extending the knee. If it is not possible to complete a unilateral heel raise or there is a lack of symmetrical varus movement of the hindfoot, it indicates the presence of posterior tibial tendon disease.
　　The auxiliary examination methods mainly include X-ray examination, which should take the foot in a loaded condition to take anteroposterior and lateral X-ray films of the foot, mainly measuring the change in the angle of the foot arch on the lateral foot film.

　　In terms of diet, it should be regular and reasonable, that is, mainly high-protein and high-vitamin foods. Choose high-nutritional value plant or animal proteins, such as milk, eggs, fish, lean meat, and various bean products. Various fresh vegetables and fruits are rich in vitamins and have high nutritional value.

　　The treatment of flatfoot should focus on prevention, and adolescents should avoid prolonged standing or overwork. Those with family history or congenital abnormalities should undergo physical therapy and deformity correction. The principle of physical therapy is to strengthen the foot internal muscles, flexor muscles, and muscles of foot inversion to enhance the support of the arch. In the early stage of the onset of the disease, in addition to the above, it is necessary to advise bed rest and wearing orthopedic shoes. For those in the spasm stage, foot hot baths can be added, and if the symptoms do not subside, manual orthopedic splint fixation can be used. For those in the rigidity stage, it should be considered to perform triple arthrodesis.

　　Observation and Follow-upMost flatfoot patients have no significant discomfort, and since the foot arch of children only reaches complete maturity at 7-10 years of age, asymptomatic flatfoot does not require treatment and does not require the use of orthopedic shoes or insoles.

　　Orthopedic Shoes or Insoles:For flexible flatfoot with pain, orthopedic shoes or insoles can be used. However, there is no evidence to show that orthopedic shoes and insoles can effectively change the structure of the arch, and the main purpose of using orthopedic shoes or insoles is to improve the comfort of the patient.

　　Splint Fixation:Used to treat rigid flatfoot, the main purpose is to immobilize, reduce pain, rather than correct. The lower limb traction splint is fixed for 4-6 weeks and can be used repeatedly multiple times.

　　Surgical Treatment:The purpose is to relieve pain that causes functional impairment, but the affected foot will lose the function of inversion and eversion after surgery.

　　Different surgical methods can be adopted according to the different causes of flatfoot, including Durham flatfoot osteotomy, medial cuneiform plantar osteotomy, triple arthrodesis, calcaneal posterior displacement osteotomy, calcaneal anterior extension osteotomy, Kidner surgery (excision of the navicular bone + transfer of the posterior tibial tendon), midtarsal joint osteotomy, subtalar joint arthrodesis, and subtalar joint immobilization.