M20: Acquired deformities of fingers and toes
M20.1: Hallux valgus (acquired)
The big toe consists of 2 toe bones. The two toe bones are connected to the metatarsal bone by a joint. The metatarsal bone is a long bone in the middle of the foot. The metatarsal bone and the toe bones of the big toe are normally connected to each other in a straight line.
With a bunion, over a period of time the metatarsal bone pushes outward towards the other foot. As a result, the ball of the foot bulges outward in that direction. The toe bones are displaced, too. With a bunion, the bones in the big toe point too much towards the adjacent toes.
A bunion can have a variety of causes. This is associated with various disorders or injuries, and a weakness in the muscles or tendons in the foot. Shoes that are too narrow can also contribute to causing a bunion.
A bunion can be painful. The skin over the bunion may be more callused than usual. The skin can also become inflamed there.
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