What are these bumps on my toes ? What are digital bursae ? Podiatry FAQs : 111

by Stephanie on October 26, 2010

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What is a Bursa?

Note the 'blister like' look of the fluid sacs beneath the skin.

A bursa is a fluid filled sac that occurs beneath the skin (plural = bursae). It is different to a blister that forms between the skin layers.  Anywhere that one hard structure of the body (namely bone) rubs repetitively against a soft part (often skin or tendon) a bursa will form.  Some bursae are ‘anatomical’ meaning everyone has one there, like the trochanteric bursa discussed in the Iliotibial Band Info Sheet.  Others are ‘adventitious’ meaning they form in response to your individual requirements.  An obvious example of an adventitious bursa is one you develop where you hold your pen.  Just like a rope rubbing back and forward over a rock, without some sort of protection the rope / tendon will fray and wear where it runs over the rock / bone. The best way to imagine the purpose of a bursa is to think of it being like a tiny balloon filled with olive oil.  It provides a sturdy little sack of fluid that gives some ‘bounce’ for direct pressure and some ‘slide’ to counter rubbing motions.

Why do I get them on the tops of my toes ?

In the past, anytime prior to the invention of antibiotics, exposing a bone to the outside world had a reasonable chance of causing death. If your shoe rubbed off the skin of your toes far enough to reveal the bone inside, osteomyelitis (bone infection) was likely to occur.  Osteomyelitis requires strong, modern antibiotics to be resolved and without these, gangrene and death would not be a rare event.  Fortunately though, our bodies can develop these little bursal cushions under the skin to stop this from happening.  So, the answer to this question of ‘why’ is obviously that something hard is compressing the skin of the toes onto the bone beneath and causing trauma. Equally obvious is that the culprit must be your footwear.

What should I do to treat a Bursa?

Firstly, remember that they are there to protect you and second, that they grow where they are needed. There is only one way to get the lumps to go away and that is to change to footwear that does not rub the skin.  If you do modify your footwear choices, although the bursa will not disappear, the fluid in the lumps will drain away and they will be much harder to see.

Do not ‘cut them out’ or puncture them with a needle.  The fluid in the sac is very nutritious to bacteria and has very little self defense to fight them off.  An infected bursa is painful and a great deal of trouble to fight off.

While it would be possible to have the sac surgically removed, another would simply grow in its place when you returned to the troublesome shoes.  The skin would also be scarred from the surgery, making the second formation more severe than the first.

It would also be possible for a doctor to inject the sac with a tiny amount of corticosteroid but again, this temporary measure would fail if the problematic shoes continued.

What is it abut my shoes that caused these bumps on my toes ?

There is several possibilities.  It will be obvious that toes that are ‘clawed up’ will make the tops of their knuckles much more prominent for the shoe to rub. If your shoes are too short, they may be forcing the toes to claw.  If your toes are already stuck in a retracted position, your shoes will need to be deep enough in the toe box to accommodate them. If your shoes are too big, you may be clawing your toes to keep them on – this makes your foot ‘thicker’ to fill out the shoe better. If your shoes are too loose, you may also be sliding around more, resulting in extra friction and rubbing. Pain in the balls of the feet can also cause clawing as the toe ends push down to ease the pressure behind them.  High heels can lead to slipping forward into the front of the shoe and jamming the toes. Lastly, general foot pronation / rolling in / dropped arch can cause the long extensor muscles on the top of the foot to work when they shouldn’t and make the toes pull back and up abnormally.  More information can be found at the Claw Toes Info Sheet and this Causes of Clawed Toes FAQ.

While all of these causes are popular, probably the biggest culprit is fashion shoes that just don’t fit. Heels that are too high, shoes that are too tight and toe boxes that are too shallow can all cause grief, even to an otherwise perfect toe.

What is the outcome of Bursitis ?

If the bursa gets enough abuse, it may get inflamed in its own right – this is known as bursitis. Generally, in the toes it is a ‘self-limiting’ condition, meaning it becomes so painful to wear the bad shoes that you have to stop thus solving the problem.  Often, toe bursae won’t get inflamed, they will dutifully go on doing their job to protect you from injury.  Unfortunately, the long term effects of your once-flexible toes clawing up inside a shoe is that they will, in time, lose their ability to straighten out.  They will become permanently and arthritically fixed into a bent position, forcing the full time adoption of sensible footwear.  A little discretion and advice from your podiatrist can help to keep your toes functioning normally into the future.  If clawing of the toes is happening for ‘internal’ reasons rather than footwear ones, orthotic treatment is strongly indicated.

Use this link to return to the Podiatry FAQs Blog, where you can search for more information.

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