Why Do Bunions Form?

Many of our patients ask:
Why did I get this bunion. Was it hereditary? Was it from wearing running shoes? Was it from an injury?  These are questions we commonly hear.
The answer is that there are multiple factors.  Sometimes we see very early onset bunions–juvenile bunions.  These almost always involve a foot structure that has been inherited that is prone to developing a bunion.  Part of this foot structure issue is a low arch or increased pronation (similar to a flatfoot).  Part of this structure may be metatarsus adductus -- where the bones in the midfoot are misaligned and there is a "headstart" forming a bunion. 
It is very rare that these would be due to wearing the wrong shoes or tight or pointed shoes at this young age.  For someone who has a mild tendency for developing a bunion, over middle-age the bunion may start forming very gradually.  This is where some factors may speed up the process such as high heel pointed shoes or a very pronated foot.  A lack of good shoe support may also even be a factor.
Once a patient comes into our office, a physical examination and x-ray is needed to thoroughly evaluate a bunion.  It is important to look to see if there is enlargement of the metatarsal head, if there is misalignment of the sesamoid bones with the metatarsal phalangeal joint (first MTP joint), and also to see if there is significant splaying or spreading of the first and second metatarsals. 
It can be helpful also to see if the foot overall has significant underlying metatarsus adductus.  Patients who have significant metatarsus adductus and a bunion usually have a magnified bunion problem and alignment problem.  The physical examination may show instability or hypermobility of the first metatarsal.  This is often a factor of the stability of the first metatarsal-cuneiform joint. 
There may even be radiographic evidence of excessive motion in this joint.  In addition the patient may have pain next to the joint over–base of the second toe.  This surprises many of our patients when they find out that the bunion doesn't really hurt but the bunion is indirectly causing the problem to the next joint over.  This is because the first metatarsal is designed to bear up to have to wait of the entire forefoot especially when the heel comes up off the ground.  When this is not occur, the next in line metatarsals get overloaded and overstressed.  One can develop problems in the second metatarsal-cuneiform joint or even a stress fracture of the second or third metatarsal.  It is important to evaluate the whole foot to determine the best treatment options.
So here some examples.  We have already mentioned juvenile bunions.  Early middle-age bunions can be from early onset (juvenile onset) and therefore will be severe and middle-age because they were already quite pronounced during the teenage years.  Other middle-aged patients will have more of a mild to moderate bunion where they just were not is prone and did not have as many factors make an them predisposed.  Some patients will also have had an injury or be prone to significant arthritis with the bunion.  As mentioned some patients may, in with non-bunion symptoms.
 
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