Bunion
A bunion, or hallux valgus, is a common foot disorder characterized by a bony bump at the base of the big toe that develops slowly due to joint pressure and misalignment.
Overview
A bunion, technically known as hallux valgus, is a bony bump on the side of the foot at the base of the big toe. These conditions develop slowly as pressure on the joint at the base of the big toe causes the toe to move out of place, leaning inward toward the second toe. Because this joint carries significant weight during activities like standing and walking, bunions can cause foot pain, stiffness, redness, and swelling.
Calluses may form where the big toe and second toe rub together or on the ball of the foot. If left untreated, bunions worsen over time, potentially making it difficult to wear regular shoes or walk without pain. Bunions can occur in one or both feet.
In most cases, bunions develop in adulthood. Rarely, children may be born with bunions (known as congenital hallux valgus) or develop them later in childhood (juvenile or adolescent hallux valgus).
Frequency
Bunions are a very common foot disorder, affecting about a third of adults in the United States. The prevalence of bunions increases with age. They are more common in women than in men, likely due to differences in foot anatomy, footwear, and genetic influences.
Causes & Risk Factors
The exact causes of bunions are unclear, although scientists suspect that both inherited and lifestyle factors contribute to their development. Studies suggest that congenital and juvenile hallux valgus tend to be related to joint deformities with a genetic cause. Little is known about the genetic contribution to bunions that occur later in life, and no specific genes involved in the development of bunions have been identified.
For bunions that appear in adulthood, inherited factors related to the shape and structure of the foot and the way the foot moves (foot mechanics) likely influence a person's risk. While it has long been suggested that wearing ill-fitting shoes is a significant risk factor, research suggests that poorly fitting shoes probably do not cause bunions on their own. However, they may make bunions develop earlier or worsen more quickly in people with an underlying susceptibility. Specific footwear risks include:
- Shoes that are too tight
- Shoes with high heels
- Shoes with a narrow toe box
Other risk factors for bunions include:
- Inflammatory diseases (such as rheumatoid arthritis)
- Osteoarthritis
- Flat feet
- Rare genetic syndromes that affect bone development, including Chitayat syndrome and fibrodysplasia ossificans progressiva
Inheritance
Bunions are a complex condition without a clear pattern of inheritance. Many affected individuals have multiple family members who are also affected. The risk of developing bunions is greater for first-degree relatives of affected individuals (such as siblings or children) as compared to the general public.
When bunions occur as part of a genetic syndrome, this feature follows the inheritance pattern of the syndrome.
Other Names for This Condition
- Bunion of great toe
- Hallux abductovalgus
- Hallux valgus
- HAV
- HV