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.
>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". LolNext, 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.pngAs 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.