The common bunion is a localized area of enlargement of the inner portion of the joint at the base of the big toe. The enlargement actually represents additional bone formation, often in combination with a misalignment of the big toe. The normal position of the big toe (straight forward) becomes outward-directed toward the smaller toes. The enlarged joint at the base of the big toe (the first metatarsophalangeal joint) can become inflamed with redness, tenderness, and pain.A small fluid-filled sac (bursa) adjacent to the joint can also become inflamed (bursitis) leading to additional swelling, redness, and pain.

A less common bunion is located at the joint at the base of the smallest (fifth) toe. This bunion is sometimes referred to as a tailor's bunion.

Who develops bunions?

Bunions most commonly affect women. Some studies report that bunions occur nearly ten times more frequently in women then men. It has been suggested that tight-fitting shoes, especially high heel and narrow-toed, might increase the risk for bunion formation. Bunions are reported to be more prevalent in people who wear shoes than in barefoot people. There also seem to be inherited (genetic) factors that predispose to the development of bunions, especially when they occur in younger individuals.

Other risk factors for the development of bunions include congenital (present from birth) abnormal formation of the bones of the foot, nerve conditions that affect the foot, rheumatoid arthritis, and injury to the foot. Bunions are common in ballet dancers.

There are three main forms of toe abnormalities in the human foot: hammer toes, claw toes, and mallet toes. A hammer toe, also called contracted toe, bone spur, rotated toe, or deformed toe, is a toe curled as the result of a bend in the middle joint. It may be either flexible or rigid, and may affect any of the four smaller toes. The joints in the toe buckle due to tightening of the ligaments and tendons, which points the toe upward at an angle. The patient's shoes then put pressure on the prominent portion of the toe, leading to inflammation, bursitis, corns, and calluses. Mallet toes and claw toes are similar to hammer toes, except that different joints on the toe are affected. The joint at the end of the toe buckles in a mallet toe, while a claw toe involves abnormal positions of all three joints in the toe.

Toe deformities are caused by a variety of factors:

Genetic. All three toe deformities may be hereditary.
Poorly fitted shoes. Claw toes are usually the result of wearing shoes that are too short. Many people have second toes that are longer than their big toes; if they wear shoes sized to fit the big toe, the second toe has to bend to fit into the shoe. High-heeled shoes with pointed toes are also a major cause of claw toes.
Bunions. A bunion is an abnormal prominence of the first joint of the big toe that pushes the toe sideways toward the smaller toes. Hammer toes often develop together with bunion deformities, and they are often treated together. Flat feet. This condition is due to poor biomechanics of the foot and may lead to hammer toes.
Highly arched feet.
Rheumatoid arthritis.
Tendon imbalance. When the foot cannot function normally, the tendons may stretch or tighten to compensate and lead to toe deformities.
Traumatic injuries of the toes.
When the toe deformity is painful or permanent, surgical repair is performed to relieve pain, correct the problem, and provide a stable, functional toe

The forefoot is subject to many different pathological deformities, many of which require surgical reconstruction. Because of the vast array of problems, which can occur in the forefoot, even more surgical procedures have been developed to correct and treat them.