Hello, I have a duck with a similar if not same issue. I hatched him and his leg is deformed, pressed up against his body and he can’t move it from the joint down. He’s now several months old and he lives happily. I tried what people suggested as I had posted it here too, I put supplements in his water and added niacin in his food. Nothing improved it. I had tried looking for a vet or something too, but found nothing. Thankfully, he’s lived through it though he just can’t walk on his leg. He hops around but he’s a happy healthy duck. Here’s what mine looked like the day he hatched.
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