Bunions (Hallux valgus)

A bunion appears as a bump that grows on the side of the foot at the base of the big toe. The condition is called Hallux valgus. This foot deformity is much more complex than a simple bump on the side of the toe. Bunions almost never occur in cultures that do not wear shoes. Pointed shoes, such as high heels and cowboy boots, can contribute to the development of Hallux valgus. This guide will help you understand what causes a bunion, how we diagnose the condition, and what can be done to treat bunions at the Southwest Ankle and Foot Center in Tucson, AZ.

Hallux valgus (bunion) is characterized by a deformity of the first metatarsophalangeal (MTP) joint with lateral deviation of the big toe and a large medial prominence (bump) at the first metatarsal head. Bunions are acquired, and can be worsened by contemporary shoes, although hereditary factors may be relevant. Symptoms of pain occur at the bunion site, and diagnosis includes a discussion about shoe wear.

What Causes a Bunion?

Many problems that occur in the feet are the result of abnormal pressure or rubbing. One way of understanding what happens in the foot due to abnormal pressure is to view the foot simply. Our simple model of a foot is made up of hard bone covered by soft tissue that we then put a shoe on top of. Most bunions develop over time, because the skin and soft tissue are caught between the hard bone on the inside and the hard shoe on the outside. Wide shoes, with plenty of room for the toes, lessen the chances of developing hallux valgus and help reduce the irritation on a bunion, if you already have one.

What Part of the Foot is Affected?

The term "hallux valgus" actually describes what happens to the big toe. Hallux is the medical term for big toe, and valgus is an anatomic term that means the deformity goes in a direction away from the midline of the body. So in Hallux valgus, the big toe begins to point towards the outside of the foot. As this condition worsens, other changes occur in the foot that increase the problem.

One of those changes is that the bone just above the big toe, the first metatarsal, usually develops too much of an angle in the other direction. This condition is called metatarsus primus varus. Metatarsus primus means first metatarsal, and varus is the medical term that means the deformity goes in a direction towards the midline of the body. This creates a situation where the first metatarsal and the big toe now form an angle with the point sticking out at the inside edge of the foot.

The bunion that develops is actually a response to the pressure from the shoe on the point of this angle. At first, the bump is made up of irritated, swollen tissue that is constantly caught between the shoe and the bone beneath the skin. As time goes on, this pressure may cause the bone to thicken, creating an even larger bump that rubs against the shoe.

The answer to decreasing the pain from a bunion is to remove the pressure. The pressure can be reduced from the outside by changing the pressure from the shoes. The pressure can also be reduced from the inside by surgically removing the bony prominence.