Causes Of A Bunion Deformity

The classic bunion, medically known as hallux abductovalgus or HAV, is a bump on the side of the great toe joint. This bump represents an actual deviation of the 1st metatarsal and often an overgrowth of bone on the metatarsal head. In addition, there is also deviation of the great toe toward the second toe. In severe cases, the great toe can either lie above or below the second toe. Shoes are often blamed for creating these problems. This, however, is inaccurate. It has been noted that primitive tribes where going barefoot is the norm will also develop bunions. Bunions develop from abnormal foot structure and mechanics (e.g. excessive pronation), which place an undue load on the 1st metatarsal. This leads to stretching of supporting soft tissue structures such as joint capsules and ligaments with the end result being gradual deviation of the 1st metatarsal. As the deformity increases, there is an abnormal pull of certain tendons, which leads to the drifting of the great toe toward the 2nd toe. At this stage, there is also adaptation of the joint itself that occurs.