@peaceout - do you mean 5 cm only femur or in total?

@ ouroboros - yes I agree and it left me deeply wondering. He was very nice and explained everything very detailedly and coherently. I did not have the feeling that he wanted to persuade me or urge me to anything but I can't believe that he has never had any problems with disproportions in cases of large lengthening distances. For me it makes no sense because surgery costs are the same no matter whether you lenghten 4 or 8 cm and I don't think he speculates on more complications which would result in making more money because honestly no doctor could have a genuine interest in a higher complication rate which leads to more dissatisfied patients and a bad reputation. I guess that maybe he assumes that somebody decides against limb lengthening when he can not have his desired height or would have to accept more surgeries because of proportions. Betz is still an option for me but now I look for other doctors, too.