3 cm at best, anything above 3 cm is no way
BS from people that never did LL and have almost no idea how it is.
Personally, till almost 6cm my rom was almost normal. After that and to avoid premature consolidation (which was very possible at my case) I lengthened almost 0.8-1mm everyday up to 7.5 cm and that lead to severe equinus.
I believe that if I lengthened slowly (at 0.5mm max per day) maybe I could reach almost 7cm without major problems.
But thats me.
Someone else could face major equinus after 5-5.5 cm. But all these bs about 3cm and breaking your legs for so minimum lengths is only a joke.
I can guarantee that at least 90% of patients could lengthen 5cm on tibias without major problems and more than 50-60% can reach 6cm without problems too.
I don't advice anyone to go further than that as 1-1.5cm more does not worth the possible complications but doing less than 5cm does not worth doing LL at all.
Only a moron could break his legs for 3cm.
That said, I hope you didnt say that ironically because then I apologize for my aggressive tone, but if you really believe that anything more than 3cm could cause problems then you are a complete idiot.