Blisters and taping

Indeed. I think it is far more multi-factoral than just `rubbing`, which is what i believe Rebecca is conveying.

With respect, I`m not so sure it`s a case of `cooking` tissue. OK, kinetic friction will produce heat, of that there is no uncertainty, but Hashmi`s paper showed the median change from baseline to the point of blister formation was 5.1°C. Is this increase of temperature enough to burn or distort tissue?

That said, the finding of elevated temperature post shear loading (for up to 30 min post blister) was very interesting. As Farina highlighted; “these temperature changes were not due to superficial frictional heat nor changes in environmental temperature”. However, she also stated “This study has provided a description of how skin temperature changes in response to trauma and also the creation of the blister with time”. Not;`how skin temperature changes may create a blister`.

So, is the increased heat due to friction alone, or a physiological vasodilation due to inflammation in response to the external shearing loads applied? Or indeed, a combination of both? The fact that all participants exhibited a rise in temperature of the skin site between the medial malleolus and the back of the heel (where no direct friction was applied) would suggest an inflammatory response, IMO. You don`t usually get blistering with inflammation of this kind, therefore I would suggest that the increase of temperature is a by-product of friction and shear, not a main causality in friction blisters.

Good to see a study attempting to`quantify physiological skin changes during the creation and early stages of healing of a foot blister`, but as always, more research is required to determine the effects of humidity and temperature in a more controlled environment. Perhaps, as Kevin suggested, cooling of the skin would have a therapeutic effect. I can certainly see the logic behind the reasoning.:drinks

Just my thoughts,

Bel

 

Thanks for clarifying Kevin. I thought 'stiction' was a typo - but its an actual word! So I looked it up on wiki.

It seems 'stiction' is not really the same as static friction. If I'm correct, static friction is a continuous force keeping two objects together. Stiction appears to be the measurement of static friction just before movement (what I have come to know as the limiting friction load - LFL).

Sorry to be pedantic but it's the sock against the skin in the majority of cases. There are two interfaces: skin-sock and sock-shoe.

Rebecca

 

Agreed blinda.

What is definitely multifactorial is what happens in a real life blister situation. For instance, there is blister development which is what we have been discussing. Then there is whether or not the blister de-roofs. Is blister de-roofing just what happens with continued blister-causing forces? Or is this a separate injury?

I make the distinction between high static friction as the cause of blisters with high kinetic friction becoming relevant as the cause of the blister de-roofing. It makes intuitive sense to me, assuming the thermal burn aspect is not so relevant.

I have made Farina aware of this discussion and hope she may find the time to contribute. If not, I will let you know when she gets back to me.

Rebecca

 

Bel:

The persistent heating of the tissues after production of a friction blister would also be present in a themal injury such as a burn. How then are friction blisters any different in the persistence of tissue heating when compared to a non-friction produced thermal injury of the skin?

I am not suggesting that cooling of the skin will only have a "therapeutic effect" as you stated. It is my contention that cooling of the skin during the friction episode may, in fact, also have a preventative effect. In other words, it is my contention that the friction blister will not form at all, even with repetetive friction on the skin, if the skin is kept cool and localized tissue temperatures never reach a critical thermal threshold.

It is my contention that the local tissue temperature must reach a certain threshold temperature in order to weaken the molecular bonds in the stratum spinosum. Then, with these molecular bonds weakened by increased tissue temperature, the shearing forces can then separate the stratum spinosum to cause a friction blister. However, with no increase in tissue temperature the shearing forces won't separate the stratum spinosum. In fact, in support of this view, Richie made the following statement in his article How to Manage Friction Blisters:

In another article on Thermal and Mechanical Skin Injuries, the following section talks about mechanically-induced blisters of the skin:

Therefore, it seems that heat is an important part in the production of friction blisters. Wouldn't you agree?

Good discussion.:drinks

 

Don't know if this makes any sense but when treating runners with a tendency to blister (in the medial arch area say) I have used fleecy web (FW), very thin fleecy self adhesive material. It has seemed to be effective to a degree. The rational of this includes:

• an insulation element
• additional surface for the sock/shoe/skin interface (though risks possible temperature rise?)

One further reason, which is the "does this make sense element".

I have considered it as possibly stabilising portions of the the epidermis. By this I'm suggesting the structure of the fleecy web (FW has a small amount of stretch capacity in one direction) against the skin minimises any tendency of the skin itself to continuously "buckle" or "ruffle up" against another surface in the shoe. The stretch component allows some epidermis motion but does not allow any one area of the medial arch skin to become more exposed to point specific friction than any other part. It acts as a scaffold to minimise the stretch glide (if it exists - skin is beyond me) of the epidermis upon the dermis. Perhaps one element of the contributory forces of blistering.

 

Hi Kevin, I think you'll appreciate this paper by Comaish, 1975 (attached) that confirm shear is the causative mechanism of blisters. But also implicate temperature not as causative of a thermal burn but as a factor relevant to the resistance of the epidermis to shear.

Then he gets a bit too mathematical and engineer-y for me but concludes:

Rebecca

 

Agreed.

The difference is observed in the structures involved and the extent and effect of increased temperature. As you know, burns are classified based upon the depth of the injury.

see here

Taken from the above link;

This is nicely demonstrated in the histological image (c) here. Note how the vesicle (blister) is subepidermal, not at the spiny layer which is observed in shear blisters.

OK. My use of the term "therapeutic effect" was not entirely appropriate. I was merely trying to state that a beneficial effect, as opposed to a detrimental one, most likely will result from skin cooling.

I do understand your contention, in fact the quote that Rebecca used from the Comaish paper suggests an "association" of the effects of friction on the skin with "damaging effects of increased tissue temperature". However, quantifying the threshold temperature for distortion/deformation of tissue in friction is still unclear. Hopefully, Farina may help us here.

Maybe, but I`m not convinced. I certainly agree that "skin temperature can affect susceptibility to blister formation". The problem is, shearing forces produce heat, so you can`t completely negate a rise in temperature related to friction. In addition to this, a localised inflammatory response to trauma occurs, further increasing/prolonging heat elevation.

In light of recent studies, which clearly show that the tearing of skin occurs specifically at the level of the stratum spinosum in shear induced blisters, I would have to disagree with the assertion “Blisters form in the subepidermis", unless it is a second-degree burn or in relation to a systemic inflammatory skin disorder.

Absolutley, 100%. But, the question remains; just how important.

I hope others are enjoying this discussion as much as we are....

 

Best thread for ages for me.

Bel or well anyone, care to have at a answer to why skin that is thickened or callously does not blister as easily ?

 

`tis cool, innit?

At a guess, I would say the cellular proliferation and epidermal thickening may withstand a greater magnitude of shear loading, and/or increased temperature, than `normal` skin (assuming the individual is in good health and the callus is not pre-ulcerative, of course).

I`ll look into it a bit more tomorrow.

 

These two excerpts seem to cover it Mike:

Knapik et al, 1995. Friction Blisters: Pathophysiology, Prevention and Treatment. Sports Med. 20(3): 136-47

Carlson, 2006. The Mechanics of Soft Tissue Damage. J Prosthet Orthot: 18:93–103. http://www.oandp.org/jpo/library/2006_04_093.asp

Rebecca

 

Thanks blinda for this.

I didn't realise that a thermal burn blister is a second degree burn!

Here's a bit more on the role of heat from Akers, 1977. Sulzberger on Friction Blistering http://onlinelibrary.wiley.com/doi/10.1111/j.1365-4362.1977.tb00755.x/pdf

Instinctively, the increased temperature / increased blistering rate could be due to the increased COF due to increased moisture alone. Apart from the following contributions, that was my view.

From Comaish

.

From Kevin

Is there anything else on this distinction?

Rebecca

 

My opinion?

Thickened callous will produce less tendency to blister because the thicker superficial layers of skin provide a thicker layer of skin to insulate the stratum spinosum from thermal transfer from the buildup of skin temperature on the skin surface that results from frictional forces on the skin surface. This explanation uses the same physics and heat transfer principles as to why tape on the fingertip prevents a burn to the fingertip more readily than touching a hot object with the bare fingertip without tape on it. Two layers of tape protects the skin even better from burns, three layers protects even better from burns, thick oven mittens protects even better than tape, etc.

How many layers of cloth adhesive tape is needed to be the thickness of a thick callous to provide an equivalent benefit of insulating the stratum spinosum from heat transfer?

Why would the body produce a thicker layer of skin if not to make the deeper layers of skin less susciptible to shearing forces and less susceptible to the local heat buildup that results from these shearing forces?

My contention is that if friction blisters were only due to the accumulation of shearing stresses on the skin surface then initial skin temperature would have no factor on the production of friction blisters. however, the abundance of research evidence points to the fact that temperature and heat are quite important in the production of friction blisters. Therefore, to say or suggest that friction blisters are only a mechanical issue and not a mechanical and heat issue seems, to me, to be avoiding the direction the available research evidence is leading us in the analysis of this question using known and widely-accepted principles of physics.

 

Bel and Rebecca:

As Mike stated earlier, it has been a real pleasure discussing these topics with you two here. I have learned a lot from you both.

Here is a Thought Experiment I want you both to consider:

Thought Experiment on Friction Blisters and Importance of Mechanical vs Thermal Factors in their Development

If mechanical shearing forces are solely responsible for friction blisters within the skin of feet and a buildup of local heat in the tissues is not important in the development of friction blisters, then no matter the temperature of the skin of the feet, the same magnitude of mechanical shearing forces will cause the same frequency and severity of friction blisters to develop in the feet.

Let's take a population of subjects and apply, to the posterior-lateral-superior aspect of the skin covering the heels of both of their feet, with a given magnitude of shearing force. The experiment is carried out at room temperature (21 degrees Celsius). On the left foot, a shearing force of X magnitude will be applied to their heels at a frequency of 2.000 Hz (2 shearing forces for every 1 second). However, on the right foot, a shearing force of X magnitude will be applied to their heels at a frequency of 0.166 Hz (1 shearing force for every 6 seconds).

The experiment is carried out until 1,001 shearing force cycles are applied to each heel so that equal magnitudes of shearing forces and cumulative mechanical trauma is inflicted on each of the heels of both feet are both equal (i.e. 1,001X). The left foot shearing force cycles are completed in 8 minutes, 20 seconds. The right foot shearing force cycles are completed in 1 hour, 40 minutes.

Two hours after beginning the shearing force cycles, the heels of both feet are inspected for friction blisters. Which one of the feet (i.e. left or right) would you expect to see more risk of development of a friction blister at the site of the 1,001 shearing force applications and accumulated mechanical trauma of 1,001X shearing forces?

Why?

 

Likewise Kevin, this discussion has been really helpful :drinks And thanks in no small part to blinda!!

What would be really helpful right now for me would be to have a recap on what we have learnt so far. My understanding is that:

1) “Friction blisters” are caused by shear – they are a shear injury.
2) Heat does not cause blisters. But heat may influence shear. The heat caused by dynamic friction may influence shear in that increased heat may reduce epidermal (stratum spinosum) resistance to shear.

Do we agree on this? If so, below is a framework I have in mind:

Blisters are caused by shear; there are several factors that influence shear:

1) Coefficient of Friction – A higher COF causes more shear eg: moisture, material characteristics
2) Pressure – Pressure is a factor that enables shear to reach blister-causing levels.
3) Epidermal characteristics – We touched on skin characteristics briefly. Plus this would be where heat fits in as it may influence epidermal resistance to shear.
4) Movement of bones – the further a bone moves relative to the adjacent skin the more the shear - biomechanical implications

Sorry to be brief but do you see any problems in moving in this direction? Are there additional factors that influence shear? Is this where you see heat fitting into the equation Kevin?

Regards
Rebecca

 

Could the thickness of tape also improve the congruency between two objects (e.g two digits) as to facilitate improved temperature distribution along both surfaces?

And hence lower the overall temperature?

ie. in my mind tape is functioning like a 'catalyst' to connect two objects more smoothly like a puzzle.

mm effect of hypoallergic tape (e.g hypafix) vs sports tape vs hypothetical malleable gold/silver tape of same thickness?

 

Of Course your opinion Kevin , I should not have used Bel´s name as an aside I think sometime we by using a name in posts ( not all as sometimes it is important) we may prevent others from joining in, as it may seem like a private conversation. I am at fault here as well, hence the " anyone else "

back to the discussion , I agree that there is heat involved, just still wondering if it a causative agent or a resultant .

Would there be any way to tell ?

 

And that, my friend, is the million dollar question.

I`ll ponder the thought experiment, Kevin :drinks

 

See my thought experiment and the research that shows that there is a 50% increase in friction blister formation with a 4º C increase in skin temperature.

My hypothesis is that without an increase in tissue temperature, no friction blister would form from the accumulation of skin shearing forces.

I would like someone to show me some research that shows that my hypothesis is not valid. From the research I have read, and from the known thermal effects on body tissues, my hypothesis seems likely.

 

Well, I reckon the left foot would be warmer as, amongst other factors (including more perspiration, due to higher frequency of loading, thus more friction), the epidermis would not have had opportunity to cool between shear loading applications as much as the right foot and will, therefore, have a greater"susceptibility to blister formation" , which you rightly highlighted Doug Richie stated. When he said, "Researchers have shown that a temperature increase of 4ºC will speed up the rate of blister formation by 50 percent", he was referring to this paper (I`d like a copy if anyone has it.....);

Hall M, Schurr DG, Zimmerman MB, et al. Plantar foot surface temperatures with use of insoles. Iowa Orthop J 2004;24:72-5

Although, notice Richie said "temperature increase will speed up the rate of blister formation". So, whilst the left foot may manifest a blister faster than the right, I think they will both blister if the tissues are mechanically stressed beyond that threshold which causes the skin to tear at the spiny layer.

Kevin, I said before that I don`t think "mechanical shearing forces are solely responsible for friction blisters within the skin of feet", or that "a buildup of local heat in the tissues is not important in the development of friction blisters". I believe increased heat does play a significant part in blister formation, but I just can`t find anything that quantifies that significance.

Cheers,
Bel

 

Agreed.

Sometimes we must use our knowledge of the principles of science to hypothesize, using coherent scientific reasoning that obey the known laws of science, as to what the most likely factors are that cause pathologies in the human body.......years before experimentation either supports or refutes our hypotheses.

Einstein calculated the correct value for the bending of light waves by gravitational fields about 8 years before these values were confirmed in actual experiments. This is the accepted process of scientific discovery.

 

:good:

So heat accelerates shear injury by its effect on the molecular bonds within the stratum spinosum. Is this the mechanism by which we propose heat is implicated in blister formation?

Rebecca

 

Rebecca:

My hypothesis:

The build up of increased temperature at the stratum spinosum , which is directly caused by the dynamic frictional forces at the superficial skin surface, help weaken the molecular bonds of the stratum spinosum. At normal skin temperatures, these molecular bonds are able to prevent low magnitude or low frequency dynamic shearing forces from shearing the stratum spinosum skin layer apart and causing friction blisters. However, at higher skin termperatures, these molecular bonds weaken which then more easily allows dynamic shearing forces at the skin surface to separate the stratum spinosum, which, in turn, leads to increased frequency of friction blister formation.

 

I don't know if I missed this, but did anyone look at heat and increased sweating. At what point do you sweat more. Is it a local phenomenon or a whole body thing?

Eric

 

I have just been thinking the same thing Eric. Increased localised heat -> increased localised perspiration -> increased localised coefficient of friction.

Also, on the heat weakening the molecular bonds at the stratum spinosum, wouldn't you think it would have more of an effect on the first two layers (corneum and granulosum) before it effected the spinosum? I guess it all depends on the relative strength of the molecular bonds, which I have no idea about.

I heard from Farina yesterday. She will be contributing to this thread next week.

Rebecca

 

Indeed. I mentioned the resultant increased friction from heat/shear loading induced perspiration when I gave my musings on the thought experiment.

That`s kinda what I was suggesting when I mentioned that burns are classified based upon the depth of the injury, which is why I am reluctant to use the terms 'thermal injury' or 'burn'. First-degree burns are superficial and involve all the epidermis and second-degree burns involve both the epidermis and dermis. Moreover, blistering associated with burns are usually subepidermal, not at the spiny layer which is where it occurs in friction blisters.

Maybe the shear force provides a pathway for the increased heat to reach the stratum spinosum?

with knobs

 

Blisters are an injury of shear at the level of the stratum spinosum (prickle layer) of the epidermis. Shear occurs both without and with relative movement against the skin (static vs dynamic friction). But shear peaks just before the point of relative movement (limiting friction load).

So it seems that in regard to friction blister formation, the shear that occurs in conditions of static friction are the most important. And that relative motion in fact reduces shear. But this dynamic friction brings other factors to the fore that are relevant to skin damage.

Could it be that the factors influencing shear (skin moisture, localised heat, material properties) are relevant both before and after relative motion but the comparative relevance to tissue damage may change?

Maybe the stratum spinosum is at risk of trauma in conditions of static friction. And the stratum corneum (and granulosum) are at risk of trauma in conditions of dynamic friction.

Your thoughts?

Rebecca

 

I did an experiment this afternoon to get an idea of the COF of materials used in blister prevention (that I had on hand). The reason is because I suspect sports tape has a high COF because Payette reports that Spenco has quite a high COF (0.5), which isn’t what I would have expected. (Payette, M. 2010. Friction management for diabetic foot problems. Audiovisual Presentation to the 36th Annual Meeting and Scientific Symposium of the American Academy of Orthotists and Prosthetists. Friction Management for Diabetic Foot Care).

The way to measure COF is via a block on an inclined plane. You increase the angle of the plane and record the point at which the block starts to slip. There’s obviously a calculation and you come up with a number that is below 1.0. The standard material to cover the inclined plane is cotton. And you apply the material to be tested to the block.

So I went to Bunnings and got a block of wood for the inclined plane, a piece of flat metal for the block, got a sock out of my draw (I don’t think it is pure cotton though) and slipped it over the wood and stuck my angle finder to the top of the inclined surface with double sided tape. Each material to be tested was adhered to the bottom of the block. I placed the block just under the angle finder, tilted the plane until the block started to slip and recorded the angle at which this happened.

I tested each material three times and took the average. The results are below in descending order:

MATERIAL / ANGLE (degrees)
White Leukoplast tape - 61
Brown Leukoplast tape - 56
Fixomul - 59
Spenco 1.5mm - 43
Spenco 3mm - 40
Compeed - 35
Vinyl orthotic cover (textured) - 28.7
Gaffa tape - 25.7
Duct tape - 22.7
ENGO - 11.3

I think that these very simplistic results should cast some doubt on the assumption that sports tape reduces the COF and prevents blisters by reducing the COF at the skin-sock interface.

Rebecca

 

Rebecca:

A better experiment for testing your hypothesis of whether sports tape reduces the coefficient of friction at the skin-sock interface would be to put your "sock-block" on tape and then compare that to sliding over actual skin. The tape just has to have a lower coefficient of friction vs skin in order to reduce heat buildup from friction, it really doesn't matter if tape has a different coefficient of friction vs other types of tape or orthosis covering materials. You could try taking a pig's foot from the butcher shop and dissecting away the skin from it to get a basic idea of the coefficient of friciton of skin vs tape. Better yet would be to use fresh-frozen human cadaver skin for your tests. This would be nearly identical to in vivo conditions and could be tested both wet and dry to see how skin moisture content affected the coefficient of friction of skin.

 

a drying agent can be salicil acid 3% in alcool . using it every day . special socks like nike dri fit running socks help to prevent blisters . if you have a haglund heel type you can use a poliuretanic protect film or idrocolloid medication

 

I've heard from Farina and she has provided permission to post her reply to Podiatry Arena:

To which I replied ...

To which Farina replied ...

 

Interesting, thanks for keeping this going Rebecca.

The wife is a p & o

We discussed this thread a while ago here question /statement was people still get blisters in extreme cold in Sweden.

 

Rebecca,

Thank you for posting Farina`s thoughts and please thank her for taking the time to respond.

Cheers,
Bel

 

Good point, Mark.

 

I'm not convinced that friction blisters are not at least partially caused by the thermal effects of excessive friction, especially with the evidence that hotter environments produce much higher frequency of friction blisters.

Also, getting a burn on the skin, from touching a hot stove, is caused by heat, and the skin will stay hot for some time after injury due to inflammation. So, Farina's statement of

really does not provide any more evidence that the thermal effects of increased friction is not needed to produce the tissue injury that causes the ultimate inflammation.

In other words, a pure thermal injury to the skin also causes heat afterwards, just like a friction blister does. Both involve heating of tissues. Therefore, I don't see how any one could so clearly conclude that heating of tissues in friction blisters has no effect in produces these injuries and that it is due solely to "rubbing causes trauma to the skin".

My bet, that if you rubbed the skin at such a rate or in such a cool environment that no excessive heat was produced, then the friction blister would never form.

 

Sounds like a challenge for our friend in the expensive beer and open-sandwich country, Mike Weber.