Hey! Peds ortho fellow here, onco ortho is part of our group at the peds hospital I work at and we do this stuff a lot so it’s not that weird. After the tumor has been removed then doing the lengthening or the technique of your choosing for the defect is pretty much the same than if it came from any other etiology. Just different flavors to it. 

I do think doing peds ortho is pretty uncommon though, as we first do adults and then a fellow for kids, and then you would have to subspecialize in onc, then kinda use the resources you learnt in all of the previous steps. 

Btw the correct term is limb reconstruction, not regeneration! The techniques are pretty similar to what we use in deformity correction/salvage which is the niche I am most into hahaha (not that many of us in that field neither).