A bunion is when your big toe points toward the second toe. This
causes a bump on the edge of your foot, at the joint of your big toe.
Description of Bunions
A displacement of two major bones of the foot (hallux valgus) causes bunions, although
not everyone with this displacement will develop the joint swelling and bone overgrowth
that characterize a bunion. One of the bones involved is called the first metatarsal bone.
This bone is long and slender, with the big toe attached on one end and the other end
connected to foot bones closer to the ankle. This foot bone is displaced in the direction
of the four other metatarsals connected with the toes. The other bone involved is the big
toe itself, which is displaced toward the smaller toes. As the big toe continues to move
toward the smaller toes, it may become displaced under or over the second toe. The
displacement of these two foot bones causes a projection of bone on the inside portion of
the forefoot. The skin over this projection often becomes inflamed from rubbing against
the shoe, and a callus may form.
The joint contains a small sac (bursa) filled with fluid that cushions the bones and
helps the joint to move smoothly. When a bunion forms, this sac becomes inflamed and
thickened. The swelling in the joint causes additional pain and pressure in the toe.