Bunions are sometimes genetic and consist of certain tendons, ligaments, and supportive structures of the first metatarsal that are positioned differently. This bio-mechanical anomaly may be caused by a variety of conditions intrinsic to the structure of the foot – such as flat feet, excessive flexibility of ligaments, abnormal bone structure, and certain neurological conditions.
The first metatarsal must line up with the big toes; it must also have a good, solid foundation. When the metatarsal bone does not have a stable foundation, the first metatarsal bone pushes away from the second metatarsal bone. The ligaments that attach to the inner side of the first metatarsal head are stretching and pulling on the bone