Download Bunion Prevention eBook

1. Biomechanics of the foot

A brief review of how bunions develop is helpful in understanding why some products on the market work better than others in treating bunions and bunion pain.
In general, most bunion deformities are a result of foot structure and function which are genetic. As the heel strikes the ground when walking, the joints of the foot unlock and absorb impact. Referred to as pronation, the arch collapses causing the feet to flatten 1. This flattening causes excessive tension on the tendon in the upper mid-foot that enables the big toe to bend upward (extensor hallucis tendon). The tendon contracts which then forces the big toe to be pulled laterally toward the second toe. This is what causes the initial deviation.

Foot Anatomy

Over time there is a backward force placed on the first metatarsal bone by the big toe, and the first metatarsal begins to move away from the second metatarsal bone. Due to these changes, there is now more pressure on the side of the first metatarsal bone from shoe pressure which causes a thickening of bone and eventually in the formation of a bunion deformity (2).


Orthotic solutions must treat the underlying causes of a bunion

Prior to selecting a treatment for bunions, it is prudent to address the underlying cause of the deformity which is not just in the forefoot where the bump is located; rather, the treatment needs to address foot function.


describe the image

Foot function includes the up and down motion of the two arches in the foot: the longitudinal arch, which is the obvious one that many refer to as the foot arch, and the anterior transverse arch, which runs transversely across the mid-foot 3.In some cases, wearing a proper-fitting orthotic will address the underlying foot function, helping to deter further progression of a bunion deformity.

An adverse affect on gait and posture

“Bunions may have an adverse affect on gait and posture due to typical pain behavior which is ‘avoidance.’ Avoidance results in what I call a ‘wobbling’ movement that amplifies throughout a patient’s gait and posture. So it is important to get the patient back to normal biomechanics as early as possible. For example, once a bunion is developed, it is usually tender to pressure. A patient may inadvertently avoid compression against the toe which will affect the entire biomechanical chain and posture. People with painful bunions are less likely to go for walks; their bunions have a limiting effect on their activity levels.”  
Markus Striebeck DC, DABCO