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[GrowGrow123]

I did my femurs in March 2023 using Precise 2.2 and will be done with the distraction phase in a couple of weeks!

Whenever I go in for X-Ray measurements, there is always a bit of discrepancy between what the ERC machine has recorded and what appears on the X-Rays. For my left left, the distracted length according to the X-Rays is always a bit more than what is on the machine. However, for my right leg, the distracted length according to the X-Rays is always less than what is shown on the machine.

As it turned out, the right leg (and only the right leg, oddly enough) was regenerating bone very quickly. To avoid premature consolidation, I had to do 4 and then later 5 sessions of 0.33mm for the right left compared to the normal 3 sessions. The nail on my right femur would sometimes make these weird buzzing / grinding / vibrating noises when lengthening with the machine. It makes some sense to me that the Precice nail was probably not extending as much as the machine showed due to it encountering resistance. This would explain the source of discrepancy for the right leg x-rays.

However, I don't have a good explanation for why the left leg x-rays would show more distracted length than the machine. Compared to the right nail, I never felt any noise or vibration when lengthening the left nail. My left leg also has more flexibility and much less tightness than the right leg.

Some questions:

1) Is the recorded length on the ERC machine generally 1:1 with what we actually expect the nail to lengthen or is there some variance here?
2) How do you know that you've fully maxed out the Precice nail? Will it make some weird noise or something?
3) Does anything bad happen if you continue to "lengthen" with the ERC machine once it has fully extended to 80mm?
4) Anyone else experience these weird grinding / buzzing / vibrating sensations when lengthening with Precise?

[Maison]

Although ERC is generally accurate, it is not always 100% accurate, and several papers have studied its accuracy.
https://pubmed.ncbi.nlm.nih.gov/24682741/
https://pubmed.ncbi.nlm.nih.gov/24758320/

However, my first concern is about the method of measuring X-rays.

X-ray image is magnified by several percent compared to the actual object.

Did you perform correction calculations for magnification when measuring X-ray images?

[GrowGrow123]

Are you using ERC-4P?

Yes, I believe so.

[GrowGrow123]

Although ERC is generally accurate, it is not always 100% accurate, and several papers have studied its accuracy.
https://pubmed.ncbi.nlm.nih.gov/24682741/
https://pubmed.ncbi.nlm.nih.gov/24758320/

However, my first concern is about the method of measuring X-rays.

X-ray image is magnified by several percent compared to the actual object.

Did you perform correction calculations for magnification when measuring X-ray images?

I didn't perform any calculations for the X-ray images. The measurements come from my doctor's readings of the X-rays (which I would assume are accurate).

[Maison]

I didn't perform any calculations for the X-ray images. The measurements come from my doctor's readings of the X-rays (which I would assume are accurate).

I'm not sure what method your doctor is using for the correction calculation, but as a reference, the video below demonstrates one way to do it.


If your doctor's calculation is precise, it could suggest that the ERC or nail movement is not accurate.

If you could share a detailed x-ray image, I would be able to attempt a correction calculation.

[GrowGrow123]

Commenting here for posterity. My left leg started making weird vibration / buzzing / grinding noises for the first time ever. So yeah that seems to be what happens when you try to lengthen and the rod is already fully extended on Precice lol.