What is a bunion? A bunion is a foot deformity in which the bunion deviates outward beyond the normal physiological angle and is one of the most common lesions of the forefoot. A bunion is generally considered to be a deformity in which the bunion deviates more than 15° outward. However, some people have a bunion that exceeds this angle without symptoms, while others have pain in the bunion area even though the bunion angle is less than 15°. After a bunion, the shape of the foot changes, affecting the aesthetics of the foot and making it difficult to choose a suitable pair of shoes. But more importantly, the structural changes in the foot after a bunion and the secondary pain have a greater impact on the basic weight-bearing and walking functions of the foot. What are the chances of bunions? The prevalence of bunions reported in the literature varies widely from 2% to 50%; in 1990, the National Center for Health statistics put the prevalence of bunions at 5.1% and Myerson put it at about 7%. The rate of bunions in men and women is 1:9-15. Simply put, one out of every 20 people will develop a bunion. How do bunions occur? 1. The most common cause of bunions is the wearing of high-heeled, pointed-toe shoes. The front part of a pointed shoe is triangular, and the high heel forces the front of the foot into a narrow triangular area, and because of the lack of elasticity in the leather of the upper, the bunion is forced to turn outward, while the little toe turns inward. Because of the high heel, it is easy to make the bunion tendon of the dorsal extension of the traction bunion slide to the outside, which becomes the contractual force of the bunion and increases the incidence of the bunion. 2. Heredity. Many bunion patients have a family history of the disease. According to the statistics of many foot and ankle surgeons, about 50% of the patients have a family history of heredity, and a significant portion of them have bunion deformity before the age of 20. 3. Abnormal foot structure. For example, rotation of the forefoot or bunion forward, tilting of the joint surface of the 1st metatarsal head, flat feet, excessive length of the 1st metatarsal, inversion of the 1st metatarsal, etc. 4, other causes: trauma leads to the relaxation of the soft tissue structure inside the metatarsophalangeal joint of the bunion and imbalance of the joint muscle force, causing bunion. Other systemic diseases, such as rheumatoid arthritis, gout and other lesions destroy the soft tissue and bone structure of the joint, lose the normal balance structure, and bunion deformity occurs under the action of other deforming forces of the foot as well as external forces such as shoes. Medical factors, such as improper removal of the second toe by a physician with no obstruction of the bunion, can aggravate or cause bunions under external forces of compression. An imbalance in the soft tissue muscles of the metatarsophalangeal joint caused by the removal of the medial measurement seed bone can also cause a bunion.