In humans, yes. This is what it looks like. In birds, I believe the legs actually get "bendable" as the bones aren't formed correctly. The baby up above has Rickets, but I'm only discussing about how the leg looks when my birds had their leg blow-outs, not the actual condition of Rickets, which CAN happen in poultry. It's usually due to a deficiency of Vitamin D.
The main focus is the knee area on the human and the hock area on the bird. See how the knees (hock) kind of "cut in" and almost touch and the calves (or shank on a chicken) look like they sway inwards? It can be a variation of this look, but the birds wind up not being able to walk.
For mine, it was a case of too much protein, not enough calcium. I've lowered the protein to a MAX of 18% after 5 weeks. I do this by mixing in layer crumbles with the chick starter until about 4 or 5 months, then switch to mainly layer pellets with chick starter mixed in with oats and catfish food. Seems to be working so far. But it's a lesson that I hope nobody else learns the hard way.
