When calf ectropion occurs in clinic, it is mainly caused by congenital factors or secondary factors. 1. Congenital factors: mainly seen in children, it is mostly caused by developmental problems, which can be manifested as bilateral calf valgus. If corrected as early as possible, such as wearing braces under the guidance of doctors and therapists, better results can be achieved. 2. Secondary factors: If the patient is elderly, it is mostly due to the presence of osteoarthritis, which can be manifested as knee valgus, unilateral patients are prone to claudication, while bilateral patients can have a hobbling gait. When combined with flat feet and patellar dislocation, patients may also experience knee pain and limited mobility. It often requires surgical treatment depending on the condition. When the fracture is caused by trauma, the fracture site may be dislocated, and if it is not surgically repositioned in time, it will heal abnormally at a later stage, which may also lead to the phenomenon of valgus deformity of the lower leg.