Is that because doctors use special medicine then lengthen?
Because dwarfs have the same soft tissue amount as regular sized people. Their soft tissue (muscle, tendons, nerves, joints etc) is not limited like a regular person of short stature. A male that is 5’5 for example has limited soft tissue and soft tissue cannot be replicated, when you lengthen it stretches but does not grow more. Don’t listen to the idiot that said you can lengthen as much as you want and proportion is key. Going over 5-6cm in tibia usually results in athletic decrease and going beyond 6cm-6.5cm will result in disability, nerve damage, early arthritis and a bunch of other other complications.
Everyone’s body are different but the general rule for 99% of everyone (and stop trying to convince yourself you are that 1% exception because your heads in your ass) is 8cm MAX for femurs (thighbone) and 5-6cm (tibia or lower leg bone)
These are not like speed limits that you go slightly over. These are the maximums, it is difficult enough to even reach that amount. A lot of people want to mentality quit at or by 7 for femurs and 5 tibia