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What is a bunion?

what is a bunion?

The term “bunion” is one of those funny ones. You’ve probably heard it before, particularly from grandma.

Every time you wear pointy shoes, someone tells you you’ll get bunions.

You’ve been told that you’ve inherited them from your mother.

So let’s cover “what is a bunion?”, “do you get them from your mother?” and “will pointy shoes cause a big toe bump?”


What is a bunion?

A bunion, referred to medically as Hallux Valgus, is a deformity of the big toe joint. It causes the big toe to angle towards the smaller toes while the forefoot widens and the big toe joint forms a bony bump on the side of it.

To understand the deformity, and how to prevent it, you’ll need a quick tour of the foot.


Anatomy of the 1st MTP

The 1st metatarsalphalangeal joint (not surprisingly we just abbreviate it to MTP) is the joint where the big toe joins the foot.

It’s a hinge-like joint designed to allow the toe to bend up and down. It’s got some capacity to tilt sideways and rotate slightly but these aren’t its main function.

The joint is under huge loads as it acts as a pivot point for propulsion during running.


The body’s response to load

Our living tissues are constantly adapting to load. It’s mostly a positive process that helps us grow and thrive. Weight bearing exercise increases bone density. Lifting weights builds muscle tissue. And so on.

The flipside is that any load can create changes, whether we want them or not.

Repetitive load can cause bone to thicken and form bumps. It can cause joints to change alignment.


The real reason behind bunions

Pronation is a normal motion of the foot. It’s a complex movement but essentially it’s a flattening of the arch and an inwards tilt of the ankle. It occurs during walking to store energy in the foot, ready for push off.

The right amount of pronation enables energy storage in the connective tissues and aligns the leg, ankle & 1st MTP for optimal drive off the ground.

If there is an excessive amount of pronation, the big toe is forced to move inwards as it bends. As this action is repeated several thousand times per hour of walking or running, the overall loading causes an adaptation.

This adaptation includes thickening of the bone in response to extra load and angulation of the joint due to the altered alignment of the ground force.

The main causes of poor pronation control are poor anatomical alignment, poor muscle control and inadequate footwear (old or poorly designed).


Can you prevent bunions?

Short answer, yes. If you can improve your foot biomechanics to ensure that the joint is aligned well during activity, there’s no reason why a bunion should form.

There will always be those prone to bunions – poor anatomical alignment, endurance runners due to fatigued leg stability and overweight people due to the excessive loading on the joint. The list is long.

But in all cases, the bunion development can be slowed or stopped with appropriate measures.

Good footwear is a given. Any shoe that allows your foot to function well is helpful. For some, a low profile shoe with improved ground feel allows them to control their loading better.

For others, they need a more structured supportive shoe to assist in limiting the rate of pronation.

Occasionally footwear isn’t able to provide the necessary support and custom or prefabricated orthotics are required.

If the issue is poor muscle control or excessive weight, their use will only be temporary. Perhaps for 1-2 years.

If the cause is bony alignment, orthotics may become an ongoing requirement.

Strength exercises, specifically targeting the muscles and movement patterns that control hip and foot rotation, are helpful. The trick is to challenge pronation control and hip rotation without adding further overload to the toe.

There are other helpful approaches – foot taping, altered exercise options and foot/ankle/hip mobility. But each of these are case-specific and don’t work for all cases of bunions.


But aren’t bunions genetic?

It’s one of the oldest “reasons” for bunions – Mum had them so you got them. But there’s no direct genetic link to the deformity!

Bunions aren’t in your DNA. But your parents aren’t off the hook yet.

The shape of your feet & legs and your muscle structure are inherited from your parents. And some legs are prone to poor biomechanics.

Poor biomechanics create abnormal loading and adaptations at the 1st MTP. This in turn leads to bunions.

So it’s not genetic, but genetics may not make it easy for you to avoid bunions.


Does wearing pointy shoes cause bunions?

Pointy shoes are commonly blamed for bunions. And it looks plausible. The shoes force the toe inwards, much like the shape of a bunion.

But the amount of force they apply to the toe is very small compared to the forces experienced during normal walking. So the shoe alone can’t generate enough load to cause bunions.

When you’re wearing pointy shoes though, the toe is held on an abnormal angle while walking. They’re also not the most supportive shoes so they can allow the foot to roll inwards (aka. pronation).

This causes an increase in the force pushing the toe across. And if you spend enough time wearing and walking in pointy shoes, that volume of force can cause adaptation and bunions.