Yeah, that was quite the blunder. Not only basic math but common sense. What I was trying to get at is that taking for instance, a lengthening of the femur 6cm, you can lengthen the tibia 6cm rather than 4.8cm and still have a ratio far closer to the original than you would create with adding just 6cm to the femur. With average limb lengths you'd probably change the ratio by 3% or so, as you've demonstrated, but the change becomes more drastic the shorter the original limbs are. With sensible lengthening in the 5-6cm range, I don't think maintaining the ratio to equality is needed at all, since most people lengthen one or the other and get away fine with a far different ratio than the original. Ideally, like you asked, I suppose you would if you wanted exactness. Nevertheless, you're completely correct and I'm quite the idiot for telling you that the opposite would be correct, and I'm sure your question was intended for Dr. Birkholtz anyway, so I'll let him answer.. Take it as a momentary lapse of reason. Sorry.