Causes of Bunions

Causes of Bunions

You can see in the following illustration comparing a foot without a bunion to one with a bunion, that the 1st metatarsal is mal-positioned from the base (bottom) of the bone. The 1st metatarsal is not crooked, bowed, or deformed - its straight and just mal-aligned from the base (bottom).

                Skeleton without Bunion          Skeleton with Bunion
            (Metatarsal bones are all aligned straight)       (Inner most metatarsal is mal-aligned)

While visual appearance of a bunion occurs at the big toe joint, its this midfoot joint that is thought (by some) to cause the bunion. Also, some believe that this joint (1st metatarsocuneiform joint) is malstructured or too mobile causing the bunion in the first place.

Bunions are thought to occur for several reasons. In most situations, a bunion is caused by a combination of factors leading the deformity.

Heredity

Genetics
Family history
Evolutionary influence

Gender

Females are more likely to develop bunions
Men may develop bunions too

Malignment

Biomechanical
- Flatfeet or fallen arches
- Pronation
- Unequal Limb lengths

Structural
- Morton’s foot
  - A type of foot where the 1st metatarsal is shorter than the others
- Loose ligaments in the foot
  - May be associated with a genetic condition
  - May occur with prenancy
- Bone structure deformities
  - Malshaped bones
  - Malshaped big toe joint
  - Congenital absence of certain foot bones – particulary the tibial sesamoid
  - Tight calf muscle and achilles tendon
    - This often occurs from long-term high heel shoes

Improper Shoe gear

Small shoes
Pointy shoes
- Causes cramping of the toes
Shoes with a tight toe box
High heels
- Results in increase pressure at the big toe joint

Injury

Acute injury.
Chronic injury

Arthritis