LL can be done in the external way( with Ilizarov devices) or in an Internal way ( precice, fitbone, g-nail, betzbone nail, etc ), keep in mind that the Internal way is a lot more comfortable but a lot more expensive too, also with internal nails you cant walk in a while, talking about the maximum amount, that changes from person to person, given your actual height I would recommend a maximum of 5 cm in tibias or 6 cm in femurs or even 7 in femurs, remember that achilles tendon limits the lengthening in the tibia And It band in femurs. About the countries you can go, It depends on your budget, if you want the best doctors for femurs or tibias with internal methods And have tons of money go to usa, want externals go to Catagni in Italy, there are good but Cheaper options. Some diaries you can check are asian123 And penguins.
