How does a bunion develop?
Flat feet are the most common cause of bunions
Bunions develop over time. In most cases, but not all, the disposition for developing bunions is hereditary due to the biomechanics of the foot, muscles and ligaments.
Overpronation which causes the feet to flatten (flat feet) is the most common cause of bunions. Overpronation places excessive pressure on the tendon in the upper mid-foot. This tendon, between the first and second metatarsal, begins to contract, pulling the big toe laterally towards the second toe. The first metatarsal begins to move away from the second metatarsal bone, causing the base joint of the big toe to spread. Once the joint stretches out, calcium deposits develop, and in some cases, nerves of the toe joint become more exposed and sensitive.
Other causes of bunions include injuries and certain activities that cause chronic inflammation. Contrary to popular belief, bunions are not primarily caused by wearing tight, “pointy-toed” shoes and/or high heels – although doing so may substantially contribute to the further progression of a bunion.
Other common causes of bunions include:
- Genetics, inherited predisposition
- Acquired “load deformity” as a result of splayfoot
- Deterioration of the base joint due to arthrosis
- Constitutional tissue weakness and muscular dysfunction
- Muscle and nerve damage, neurological dysfunction, chronic inflammations or injuries to the foot