Tibia/femur ratio for proper function

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which is the range of Tibia/femur ratio to maintain the proper function of the limbs? i have read that the range should be maintained between 0,8 to 1.0

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I've seen those numbers cited too, seems about right. That's the ratio of Tibia to femur right? (.8=Tibia is 80% as long as the femur?)

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As I read I'm understanding it. A very wide range of knowledge

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Crural index=tibia/femur=TML/FBL.

TML (Tibia Maximum Length)= distance from the superior articular surface of the lateral condyle to the tip of the medial malleolus.

FBL (Femur Bicondylar Length)= distance from the most superior part of the head to a plane drawn along the inferior surfaces of the dystale condyles.

Neanderthal Man had a crural index of about 78; Homo Ergaster had a crural index of about 88.5.

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Today the lowest crural index is found in the Lapps and it's about 79; in recent Europeans the lowest value is about 80 (mean of 82.8 minus 2.5 of standard deviation); in west africans is at its highest level: mean of 85.8 plus 2.5 of standard deviation.

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Generally speaking femur is 52-56% of your totally leg length

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Generally speaking, exactly.

Solving the 1st system where:
X+Y=1
X/Y=0,78
X=tibia
Y=femur
You have that Y=56% of X+Y.

With X/Y=0,885 you have that Y=53% of X+Y.

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Quote from: apoxyomenos on November 01, 2016, 02:30:46 PMGenerally speaking, exactly.

Solving the 1st system where:
X+Y=1
X/Y=0,78
X=tibia
Y=femur
You have that Y=56% of X+Y.

With X/Y=0,885 you have that Y=53% of X+Y.

Your math is wrong...

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What happens if you tibia become longer than your femur?

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Zaney,
If you solve the system you obtain the values above indicated. Where is the mistake in your opinion?
Let's assume that x+y=1 meter
Solving the system, in which the crural index=0.78, you get y=femur=0,56m, that related to the total length of the legs (1m) means 56%.
Same thing if you sole the system,  by taking into consideration the crural index=88.5, you get 0.53m, that means y=femurs=53% of the total length of the legs, that is 1.