Will I gain the same amount of height that my X-ray shows?

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Hey guys

I plan on doing tibia LON for 5cm.

I spoke to a guy that done LON for his femurs. He said his xrays showed he lengthened 8cm...but in reality when he measured himself he only gained 7cm of height.

Is this normal or was he an anomaly?  Should I automatically subtract 1cm of height from whatever my xrays will show?

This has concerned me a little bit...would love you hear from you guys!

Thanks

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People are terrible at measuring themselves.  Due to the angle of the femur, an 8 cm gap doesn't translate to the top of the head's being 8 cm heigher, but it's close.  There's a math formula you can use to calculate the exact difference.

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Quote from: Medium Drink Of Water on April 25, 2022, 01:23:47 PMPeople are terrible at measuring themselves.  Due to the angle of the femur, an 8 cm gap doesn't translate to the top of the head's being 8 cm heigher, but it's close.  There's a math formula you can use to calculate the exact difference.

I understand...with that being said... would you say lengthening tibia's is better in terms of getting the same height that your xrays shows?

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I measure myself properly, cause sadly I'm pretty obssesive in that regard. I did 6.1 cm in femurs, and at least the last month I only had 5.2 cm in real height. My doctor thinks it's due to the fact that my back is still weak and my posture is not as good as it was, so I'm working on it. Will update after I'm 100%, but in any case it's something to take into account. I would have done 5 mm had I known.

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hi there! do you by chance know the mathematic formula?

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Quote from: liltunechi on April 25, 2022, 02:02:13 PMI understand...with that being said... would you say lengthening tibia's is better in terms of getting the same height that your xrays shows?

Yes, since the tibia is pretty much vertical.  Its anatomical axis and its mechanical axis are virtually identical.

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Quote from: jlk on April 25, 2022, 02:35:43 PMhi there! do you by chance know the mathematic formula?

It involves compensating for the Q angle, which can vary a little bit from person to person.  As long as you know your Q angle and some high school level math you could calculate it.

https://en.wikipedia.org/wiki/Genu_valgum#Q_angle

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Is best way to measure height gained by xray to measure the gap or on the precice nail itself? I have had doctors do both while measuring by xray.

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Quote from: liltunechi on April 25, 2022, 01:06:21 PMHey guys

I plan on doing tibia LON for 5cm.

I spoke to a guy that done LON for his femurs. He said his xrays showed he lengthened 8cm...but in reality when he measured himself he only gained 7cm of height.

Is this normal or was he an anomaly?  Should I automatically subtract 1cm of height from whatever my xrays will show?

This has concerned me a little bit...would love you hear from you guys!

Thanks

There are 2 possibilities that are causing this femur length gain to actual height mismatch.

1) Q-Angle of femurs, because the femur bone is not perpendicular to the ground (as mentioned above)

2) That femur LON patient may have measured his height too early, before he can fully stand up straight. After lengthening is done, it can take months to fully stretch out your hip flexors and quads, so that you can stand up straight to get maximum height.

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I have a video that analyzes the Q-angle and the effect on actual height gained. It starts at 1:36

https://www.youtube.com/watch?v=-q4vNw6vIGs


Quote from: jlk on April 25, 2022, 02:35:43 PMhi there! do you by chance know the mathematic formula?

The theoretical mathematical formula would be (it requires a scientific calculator):

Actual height gain = ( (Q angle) cos ) * Actual femur lengthened

For example, a male femur lengthening patient with a Q-Angle = 13 degrees lengthened 8.0cm on the femurs.

Actual height gain = (13 cos) * 8.0cm = 0.97437 * 8.0cm = 7.795 cm