You shouldn't lengthen more than 5 cm max. According to cyborg4life in a recent interview lengthening more than 3.5 - 4.5 cm on the tibias is considered overlengthening for most people and can give all kind of issues later down the line.
Personally I don't understand people doing tibias at all... The complication rate is higher mainly because of the 2 bone being cut (tibia and fibula) so it's more risky. Malalignment is also a big issue with tibias. You can gain a less amount of height. It heals slower. Also only doing Tibia usually gives a much higher chance of early arthisis and problem with the rest of leg functions, where lengthening the femurs shouldn't give the samme issues:
https://pubmed.ncbi.nlm.nih.gov/26398436/
- 29:40
All these are plain nonsense.
External tibias is by far the safest way for LL. The cheapest also.
Furthermore you could gain safely 6cm which is about 7cm on femurs in real height due to the curve in femur bones.
Also, premature arthritis is more probable with femurs, especially if you insert the nail from the knee, than with external tibias.
And last but not least for most of LLers tibia LL looks much better than femur as longer tibias make.you appear taller and more.athletic than longer femurs.
In a few words I really can't understand why someone who wants only one LL for about 5-6 cm total lengthening does anything else than pure external tibias which is the safest, cheapest and less painful way of LL.