X-Legs is a very simple thing. The fact that idiot doctors who study orthopedics for years cannot prevent it just highlights the lack of competence across all fields. The tibias have a natural inward curve. This helps the overall axis from the femur to the foot align as God intended. For most people it isn't much. During lengthening, many doctors only go to the X-rays rather than apply common sense. The lengthened area, say 5-8cm or whatever, should also follow this natural curve, just like the rest of the tibia. However, most doctors try to get this lengthened area very straight. Sometimes, really stupid doctors like Mirzoyan in Armenia, even try to bend it outward. Keep in mind, that from the spot of the fracture, even a few degrees can make a big difference as it alters the remainder of the tibia. I mean if for example the tibia had a natural 5 degree inward bend, and the lengthened area had even 1 or 2 degrees outward, it would swing the whole leg from that spot in that direction. Rather than allowing the new bone to follow the natural pre LL curve, it basically gets too straight or even outward. This is what leaves people with X-Legs. The patients are mad because it looks bad and is not normal and bad for the legs. The idiot doctors are mad and point to the X-rays and say "look it is so straight!"
My case was tough because Mirzoyan, the worthless dog he is, put both my left femur and tibia in an X shape meaning that I had to correct them both.
X-Legs should be fixed because it really looks bad. If you put your legs together but your ankles don't touch then you probably have X-legs.