Involvement Of Mechanical Stress In Androgenetic Alopecia | Von Mises 2d Analysis Models

[VonMises]

Hi

I'm going to post my research findings in this thread, hopefully you will find it interesting. The research is based on the 2D Von Mises stress model proposed in the article below, which has been reproduced in LISA and alternative Von Mises 2D analysis models are created in order to investigate their stress pattern and how the stress pattern changes by applying additional forces.

Original research:

Figure: (a) Von Mises stress in the galea. Hairline and force vectors are configured as laterally developed frontal bellies. (b) Schematic sequence of androgenetic alopecia transition zones according to Hamilton–Norwood scale (typical pattern) (c) Regression line and Pearson product-moment correlation coefficient between A and B

Link: ijtrichology.com/article.asp?issn=0974-7753;year=2015;volume=7;issue=3;spage=95;epage=99;aulast=Tellez-Segura

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The 2D Von Mises stress model “With half opposite force rear” is made in LISA FEA v. 8.0.0 and is made public on github for open source public usage:

Link: github.com/VonMisesFEA/LISA/blob/master/scalp_2d_analysis.liml

 

[VonMises]

New research:

Reproduced model in LISA:

It appears that the von Mises stress pattern in the reproduced model is exhibiting more similar patterns to the schematic sequence of androgenetic alopecia transition zones according to Hamilton–Norwood scale shown in the original research than the von Mises stress model in the original research, namely the frontal low stress region (shown in pink color).

 

[VonMises]

With added fixed support above the frontal forces:

It appears that by adding a fixed support above the frontal forces prevents them from reaching the rest of the model, and creates a uniform tension distribution throughout the model (shown in pink) without exhibiting any of the Hamilton–Norwood pattern shown above.

 

[VonMises]

With equal opposite force:

By adding an equal opposite directed force the von Mises stress pattern is similar to the one abtained when adding a fixed support above the frontal forces.

 

[VonMises]

With double opposite force:

By adding an opposite force which is 2x higher than the frontal forces the von Mises Stress pattern appears to take on a similar shape as the reproduced model and show Hamilton–Norwood pattern, but with some minor differences (e.g. see the pink area in the very front).

 

[VonMises]

With equal perpendicular force (outside):

 

[VonMises]

With double perpendicular force (outside):

 

[VonMises]

With equal perpendicular force (from inside):

 

[VonMises]

With double perpendicular force (from inside):

 

[IdealForehead]

Wow! This is very cool.

For anyone looking for information about how these stresses may contribute to the pathogenesis of male pattern baldness, I wrote a thread about that based on the same research yesterday:

Why the Galea is the Fundamental Cause of Male Pattern Balding (& Androgens Are Secondary)

I can't tell from your diagrams. Is your mesh network based on a 3D model of a male skull shape, which has then been flattened to 2D? Or is based solely on a 2D flattened model of the scalp with only 2D stress distribution?

Of course in an ideal model we should be working from a 3D model with 3D stresses, as with the natural scalp.

If I was better with ANSYS I'd do some modeling too.

 

[IdealForehead]

It appears your first model and the "double opposite force" models best reflect what we see in the real world.

With added fixed support above the frontal forces:
View attachment 84420
It appears that by adding a fixed support above the frontal forces prevents them from reaching the rest of the model, and creates a uniform tension distribution throughout the model (shown in pink) without exhibiting any of the Hamilton–Norwood pattern shown above.

This would represent a manifestation of a possible new theoretical treatment I had suggested in the other thread, which would be to add scalp/galeal anchors to the galea to unload it, like endotines but more permanent.

The problem with approaching the problem in this way is that if androgen sensitivity in the follicles is epigenetically programmed by the galeal tension very early in life/development, then even "unloading" the galea in this way in adulthood may not stop hair loss mediated by this androgen sensitivity.

However, based on our understanding of this model as well as the results produced by Botox, one would expect the pathology of hair loss to be considerably reduced by such anchoring.

That doesn't mean anchoring in this way would be a good idea or feasible. But it's interesting to conceptualize.

Thanks for posting all this. It's very interesting.

 

[Calchas]

@VonMises
Have you studied Dupuytren's and Ledderhose's contractures?
These are fibrocontractive disorders that occur at an analogy of 10/1 for male and females respectively,
and their androgen dependence has been shown in a few studies.
https://www.ncbi.nlm.nih.gov/pubmed/11853085

I think that similarly,male pattern baldness is actually an epicranial fasciosis induced by the synergistic action of androgens and mechanical tension.

 

[IdealForehead]

@VonMises
Have you studied Dupuytren's and Ledderhose's contractures?
These are fibrocontractive disorders that occur at an analogy of 10/1 for male and females respectively,
and their androgen dependence has been shown in a few studies.
https://www.ncbi.nlm.nih.gov/pubmed/11853085

I think that similarly,male pattern baldness is actually an epicranial fasciosis induced by the synergistic action of androgens and mechanical tension.

Most of the articles I reviewed on this subject suggest that there is a feedback loop between tension and androgen expression, whereby tension causes inflammation and increased androgen production/sensitivity, and then androgens through inflammation and muscle hypertrophy stimulate further tension.

And so the loop goes unless interrupted.

 

[VonMises]

With equal perpendicular inward force (from inside):

 

[VonMises]

With double perpendicular inward force (from inside):

 

[VonMises]

With equal perpendicular force (from outside):

 

[VonMises]

With double perpendicular force (from outside):

 

[IdealForehead]

I don't mean to interrupt your train of posting/thought too much, but I just want to reflect that I find it very interesting how subtle changes in the frontotemporal stress modeling can induce such broadly different patterns of tension through the scalp.

Thus it seems reasonable to expect that subtle differences in the insertion/origin points of the scalp muscles to the galea and skull shape differences could absolutely explain the normal degree of variation we see in terms of how different men go bald.

ie. If your stress pattern naturally targets the front of your hair more than your crown, you may expect a more frontal balding pattern, or vice versa. Or if your stress pattern manifests more diffusely over the whole top of the skull like the "double perpendicular force (outside)" model, you might be expected to develop a more diffuse balding pattern.

 

[Calchas]

Most of the articles I reviewed on this subject suggest that there is a feedback loop between tension and androgen expression, whereby tension causes inflammation and increased androgen production/sensitivity, and then androgens through inflammation and causing muscle hypertrophy stimulate further tension.

And so the loop goes unless interrupted.

There is a study,which i can't find right now,that showed that bald men have thicker galea and thinner scalp skin with less subcutaneous fat,
whereas non-bald men have thinner galea and thicker scalp skin overlying the galea with more subcutaneous fat...That makes absolute sense...

When a muscle is exercised, it is anabolised,it increases its volume.That occurs at the expense of the overlying skin and especially the subcutaneous fat which catabolise...The muscle needs more energy,so it sends paracrine catabolic signals to the overlying tissues which as a result become thinner...
male pattern baldness is not a rare and exotic disorder.It occurs in 50% of men at the age of 50,and only 10% of men will be unaffected by the disorder above the age of 70...That means that the mechanism should be very simple.

 

[Calchas]

It's interesting that the area with the lowest tension corresponds to the area where there are remnant hairs.