Is it visibly broken? If there is skin puncture the odds are very low but you should apply a chicken-safe antibiotic to any open wounds.
Maybe someone knows if there is a safe pain medication for chickens?
My hen broke her leg and recovered almost completely so that she is finally able to run again. But it was a slow process. I would do whatever needed to keep your chickens stress level down. If segregating her doesn't bother her then I would do that for now so she isn't hassled by any other chickens. She needs some calm, special treatment for at least the first few days. Keep the temp comfortable, food and water right where she can get it easily. I might even put some electrolytes in her water for a week or so.
Best of luck to you and your silkie!