About tibia:femur=0.8 ratio for skeletal health

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Some people often quoted the research paper saying that t:f ratio to be kept for 0.8
but does it mean
femur bone length : tibia bone ? or
femur upright length(from your groin to knee) : tibia
?

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Bone length.

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i just found it.
https://pubmed.ncbi.nlm.nih.gov/26398436/

this article.

I can't find exactly what it says as full article isn't available but i also feel like it's saying femur length.

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Quote from: lovinglonglegs on June 11, 2023, 04:20:38 AMi just found it.
https://pubmed.ncbi.nlm.nih.gov/26398436/

this article.

I can't find exactly what it says as full article isn't available but i also feel like it's saying femur length.

It is talking about femur length, in relation to tibias. The ratio. The title says quite succinctly what the study is all about.

What's interesting is how it confirms what everyone says--lengthen femurs over tibias if you had to pick one, since the risk of complications are less. But most are really only thinking about the post-surgical issues, such as ballerina foot, neuropathy, non-unions, price, and things of that nature. But now hip and knee arthritis are in the picture, which can be quite debilitating. I don't have access to the full article, but it would be interesting to see how bad the arthritis is. It's a significant predictor, but that doesn't necessarily mean the arthritis is "world ending levels of pain", or "discomfort after heavy use". Regardless, I would error on the side of caution...and who wants to willingly give themselves arthritis if it can be avoided by just lengthening femurs instead?

On the other hand, having long tibias may more aesthetic vs having long femurs. Although the studies done on this show that the effect on attractiveness is quite minimal and can be ignored. ( https://royalsocietypublishing.org/doi/10.1098/rsos.170399 ). Having those extra inches, may it be on the tibias or femurs, will do far more for attractiveness. I've never heard somebody say, "Your tibia length is sooo hot and turning me on!" Lol

The most important factor is talking to your Dr and getting accurate measurements of your femur and tibia, so that you can calculate your own T:F ratio. From there, you can make an educated and safe decision.

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I'm that guy lol. And I agree with the comment above this one.

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So if I can only my tibia I have a high chance of long term problems in the future then if I just did femurs  if I wanted to get 2 surgeries and wanted a perfect Ratio how many inches on femur and tibia should I get

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Quote from: Thekollecter on June 11, 2023, 03:52:11 PMSo if I can only my tibia I have a high chance of long term problems in the future then if I just did femurs  if I wanted to get 2 surgeries and wanted a perfect Ratio how many inches on femur and tibia should I get

Tibia amount = 0.8 * femur amount

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So if it is the case that skewing the ratio past 0.8 can cause arthritis, then presumably getting two surgeries (once tibia, once femur) is actually a safer option?

Also, do some people naturally have a ratio beyond 0.8? I wonder whether they would be at similar risk or if it’s more down to the surgery itself.

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Quote from: LG1816 on June 12, 2023, 01:58:08 PMSo if it is the case that skewing the ratio past 0.8 can cause arthritis, then presumably getting two surgeries (once tibia, once femur) is actually a safer option?

Also, do some people naturally have a ratio beyond 0.8? I wonder whether they would be at similar risk or if it’s more down to the surgery itself.

>then presumably getting two surgeries (once tibia, once femur) is actually a safer option?

Do your femurs first, then tibias second. Or you could do them simultaneously. But in general, you probably want to avoid doing tibias first or tibias alone.

>Also, do some people naturally have a ratio beyond 0.8? I wonder whether they would be at similar risk or if it’s more down to the surgery itself.

Yes, some people have a ratio beyond 0.80. Take a look at this study ( https://www.researchgate.net/publication/351568076_Normative_Values_for_Femoral_Length_Tibial_Length_and_the_Femorotibial_Ratio_in_Adults_Using_Standing_Full-Length_Radiography )

Keep in mind, they are comparing F:T, not T:F, so that's why it says 1.28:1. 39/50 = 0.78 It can be difficult reading these papers and calculating the numbers, but the important thing is that--for our purposes its 0.78. "Just trust me, bro". Lol

Next, take a look at this image:

https://www.researchgate.net/publication/351568076/figure/fig3/AS:1024819210493953@1621347348218/The-distribution-of-the-differences-in-limb-length-a-femoral-length-b-and-tibial.png

As you can see, the discrepancy is no more than 1.2 cm in 324 paired adult limbs (Someone please correct me if I am interpreting this incorrectly!)

So while some people have a ratio beyond 0.8, it's unlikely to be by an extreme amount. Take this for example--The average femur is 50cm, and the average tibia is 39cm, so T:F ratio of 0.78. If the discrepancy is typically no more than 1 or 1.2 cm, that would mean a T:F ratio of 0.804. Now lets say someone lengthens tibias to the commonly accepted "safe level" of 5cm. 39 + 1.2 + 5 = 45.2, then take the average femur of 50cm and... That is a T:F ratio of 0.904!!!

I hypothesize that skewing the ratio .004 above 0.8 will not cause hip or knee arthitis, but a whopping .104 probably would! That's a 2500% increase!

>I wonder whether they would be at similar risk or if it’s more down to the surgery itself.

They probally would, but in the study of 324 adults, there was not one person with such an extreme disparity. If someone did have a condition like that, they would likely be a prime candidate for non-cosmetic limb lengthening, or some other orthopedic procedure. Remember, there are many non-cosmetic reasons to get limb lengthening.


...long pause...


Phew. I hope I earned my keep with that one! Haha Please, if I incorrectly did the math or misinterpreted the results, anybody feel free to correct me.

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Great post. Those studies were interesting.

Regarding the original study, it's a shame we can't read the full paper without paying, because I wonder what their thoughts are on their thoughts on the results.

Have we any members here who have suffered from arthritis symptoms?