I recommend anyone else researching this breed to join the Facebook group for them. It doesn't seem to be widely discussed elsewhere, but this breed (Silvers in particular) is extremely prone to leg issues that are nearly always fatal (I would say always but maybe there's an exception that I haven't heard). Many start with knees turned outward, some with total paralysis of one or both legs...
I haven't heard of any vitamins or treatments being successful yet (but would welcome positive stories). Some think it's a neurological issue... personally I think it's something in the tendons, but wasn't able to pop anything back in on my poor little rooster.
I have one of his sisters in isolation now with wobbly knees, a stuck egg (?) and who knows what else. They were difficult, demanding chicks compared to my Bresse and Wyandottes, and seem susceptible to every passing problem. This is going to get worse IMO because everyone is selling eggs and chicks the moment their birds start laying. I've seen people lose most of their clutch to seizures and leg problems then go on to breed the survivors. IMO... stay far away from these beautiful, sweet birds until something changes. It's very sad.