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Author Topic: ratio of femur and tibia (How to calculate)  (Read 5573 times)

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Stretch

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Re: ratio of femur and tibia (How to calculate)
« Reply #31 on: May 01, 2021, 06:38:58 AM »

"most" people is an understatement, it is probably more than 99.99999% of people who DON'T have a longer tibia than femur (meaning, their femur is longer). If the average tibia/fem ratio is 0.80 with a standard deviation of 0.03, then 3 standard deviations up would be 0.89 (tibia shorter than femur), which would be the top 0.15% (99.7% is 3 standard deviations coverage centered at 0.80), and 4 standard deviations up would be 0.92 (tibia still shorter than femur), which would be the top 0.0005% (99.99% is 3 standard deviations coverage centered at 0.80), and 5 standard deviations up would be 0.95 (again, tibia still shorter than femur), which would be the top 0.00003% (99.99994%% is 3 standard deviations coverage centered at 0.80), which at this point is the 5-sigma threshold for scientific observations to become a discovery.

At this point it is 1 in 3.5 million people who have a 0.95 tibia to femur ratio, and the tibia is STILL shorter than the femur.

The 6th standard deviation above the mean would be an astronomical number, and even then it is still not more than 1, it is 0.98. You'd need to hit the 7th standard deviation which would be much much much higher than 1 in 3.5 million to achieve a ratio of greater than 1, which would mean the tibia is longer than the femur.

For all purposes and intent, a longer tibia than femur is not natural and doesn't occur in more than 99.9999% of normal humans.

Why do I care enough to type all this? I don't, I am just bored and like math. *shrugs*. Nothing personal Ozzi lol.  ;) :-*

References:
https://pubmed.ncbi.nlm.nih.gov/26398436/
https://en.wikipedia.org/wiki/68%E2%80%9395%E2%80%9399.7_rule
https://blogs.scientificamerican.com/observations/five-sigmawhats-that/#:~:text=So%2C%20what%20does%20five%2Dsigma,about%201%20in%203.5%20million.

So Femurs are typically longer then Tibias.

By design it would seem Tibias are shorter for a reason (mechanically). Would lengthening them and ultimately changing the ratio In favour of the Tibia place the body at a disadvantage?


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Serilium

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Re: ratio of femur and tibia (How to calculate)
« Reply #32 on: May 01, 2021, 07:06:13 AM »

So Femurs are typically longer then Tibias.

By design it would seem Tibias are shorter for a reason (mechanically). Would lengthening them and ultimately changing the ratio In favour of the Tibia place the body at a disadvantage?

Increased wear on the hip and knee and potential for more arthritic issues if your tibia/femur ratio gets higher (tibia LL). This can happen the other way around too with femur lengthening, but lesser degree.
« Last Edit: May 01, 2021, 07:28:07 AM by Serilium »
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Stretch

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Re: ratio of femur and tibia (How to calculate)
« Reply #33 on: May 01, 2021, 08:19:26 AM »

Increased wear on the hip and knee and potential for more arthritic issues if your tibia/femur ratio gets higher (tibia LL). This can happen the other way around too with femur lengthening, but lesser degree.

Ah I see, it sounds as Femurs would be a wiser choice for one procedure?

Or ideally both Segments F +T to avoid complications mentioned.
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