A bunion is an outward movement of the thumb of the foot. The bunion is usually formed for the following reasons: 1. congenital, since childhood, as we get older, the bunion will gradually aggravate, resulting in local pain and other symptoms. 2. acquired, such as wearing high-heeled shoes, narrow shoes in front, the whole bunion is squeezed outward for a long time, forming local inflammation and scars over time, the bunion will remain outward. 3. caused by trauma, such as fracture or joint capsule injury, after the local injury is not fully recovered. 4. Rheumatoid, ankylosing spondylitis, and rheumatic diseases cause joint destruction and bunions. Therefore, there are various causes of bunions, which should be further determined according to different situations.