What is a bunion?

A bunion^[1] is a bony bump that forms on the inside of the foot at the base of the big toe. This bump may be painful, swollen, or visibly irritated. Bunions occur as a result of a deformity in the metatarsophalangeal (MTP) joint. This deformity causes the bones in the front of the foot to shift out of place, pulling the tip of the big toe toward the smaller toes and forcing the MTP joint to protrude. It’s appropriate, then, that the Latin name for a bunion is hallux valgus^[2] (hallux meaning “big toe,” and valgus_ meaning “turned away from the midline of the body”).

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Bunions can be painful: the enlarged MTP joint and bursa^[3] (the fluid-filled sac surrounding and cushioning the joint) often become inflamed^[4], causing stiffness and pain. The skin over the bunion might also become red or sore as a result of friction against tight footwear. Wearing tight, narrow shoes may worsen an existing bunion or cause a new one to develop. For this reason, one of the most effective approaches to relieving bunion pain is finding footwear that doesn’t constrict or irritate the bunion. In some cases, however, bunions may become so severe that even the right footwear can’t entirely prevent pain and swelling from occurring. At this point, surgery is usually required.

Bunionette

Some people may develop a small bunion, called a bunionette^[5], on the little toe. These bumps, also known as tailor’s bunions, form on the outside of the foot in the joint found near the base of this toe. While found in a different location of the foot, bunionettes are similar to bunions. They, too, may result from a combination of genetic and environmental factors^[6], including foot structure, arthritis, and wearing ill-fitting shoes.

How common are bunions?

Bunions are common: one systematic review found the prevalence of bunions to be roughly 23%^[7] among adults between the ages of 18 and 65. The likelihood of developing a bunion increases with age. How severe a bunion becomes, however, has been found to be independent^[8] of age (as well as other factors, including a person’s BMI, biological sex, and whether they have pain in other parts of their body). Women are also much more likely to develop bunions than men: while roughly one-quarter of American men develop bunions, these growths affect more than half of American women^[9]. It has been proposed that restrictive shoes, such as high heels (which move the body’s weight forward and force the toes into the tip of the shoe), may be partly to blame for the fact that bunions are ten times more common^[10] in women than in men.

What causes bunions?

Bunions develop slowly^[11] as a result of consistent pressure on the joint found at the base of the big toe (the MTP joint). Over time, as the foot’s bone structure changes, the big toe begins to lean toward the smaller toes and the bump known as a bunion forms. It’s unclear exactly what causes certain people to develop bunions. While there are many theories as to why they develop, it has been supposed that bunions occur as the result of a combination of factors^[12]:

• Genetics and foot structure: Some people may be predisposed to develop bunions due to their inherited foot shape and structure. Bunions have also been shown to run in families, as certain foot types (which are hereditary) are more likely to develop bunions than others.

Other features, such as flat feet, low arches, and loose joints and tendons, also increase the risk of having bunions.

• Foot stress or injury: Repeated stress on the feet—particularly from wearing narrow, pointed shoes that force the toes into an unnatural position—may cause a bunion to form. However, experts have not determined^[13] whether tight, narrow, or high-heeled shoes actually cause bunions or whether choices in footwear just contribute_ to the development of bunions.
• Congenital deformity: Congenital deformities (deformities present from birth) in the anatomy or structure of the feet may increase the likelihood of developing bunions.
• Pre-existing health conditions: Bunions may be linked to certain inflammatory conditions^[14] (like rheumatoid arthritis) and neuromuscular conditions (such as polio).

Risk factors for bunions

Certain factors may increase your risk^[15] of developing bunions, including:

• Occupation: Working at a job that requires frequent standing and walking increases the likelihood of developing bunions. Certain athletes, such as ballet dancers, may also experience repeated stress on their feet, causing bunions to develop.
• Pregnancy: During pregnancy^[16], certain hormonal changes cause the ligaments to loosen and flatten the feet. Because of this, women are susceptible to developing bunions (as well as other foot problems) during pregnancy.
• Footwear: As previously stated, it is contested whether restrictive shoes cause bunions or not. However, it is likely the case that wearing shoes that crowd the toes and force them into unnatural positions at least contributes to the development of bunions.
• Rheumatoid arthritis: Having rheumatoid arthritis, the most common form of autoimmune arthritis, can increase your risk of developing bunions.

Bunion symptoms

Bunions start out small and take time to develop^[17]. They generally don’t cause noticeable symptoms until they’ve grown in size—thanks to continued aggravation and pressure—that bunions become irritated or painful. This can make everyday things like walking and wearing certain types of shoes difficult. Common signs and symptoms^[18] of a bunion include:

• A hard, bony bump that protrudes from the base of the big toe on the inside of the foot
• A big toe that begins to cramp or overlap with the second toe
• Soreness, tenderness, swelling, or redness around the joint of the big toe (MTP joint)
• Corns or calluses: these growths commonly form as a result of friction at the site where the big toe and the second toe rub together
• Consistent pain or pain that worsens and dissipates
• Stiffness and limited range of motion in the big toe
• Hardening^[19] of the skin on the bottom of the foot

Bunions don’t usually require medical intervention. However, talk to your healthcare provider—or ask for a referral to a specialist, such as a podiatrist or an orthopedic foot specialist—if you have:

• Constant pain in your foot or big toe
• A large, visible bump on the MTP joint
• Decreased or limited range of motion
• Difficulty finding footwear that fits properly or doesn’t cause pain

Complications from bunions

Bunions can lead to a number of related foot complications^[20], including:

• Bursitis: A painful condition that occurs when the fluid-filled sac surrounding the bones near the MTP joint (called the bursa) becomes inflamed. Chronic pain and arthritis can also develop when the connective tissue covering the MTP joint (articular cartilage) becomes damaged.
• Hammertoe: An abnormal bend (called a contracture deformity) that occurs in the middle joint of a toe (usually the second toe). Hammertoe usually progressively worsens over time and can eventually cause pain and pressure.
• Metatarsalgia: A condition that causes pain and inflammation in the ball of the foot.