I think it depends on where it's broken. If it's broken at the lower leg near the ankle, I would think that they would be able to move the whole leg at the hip. When they do that, the rest of the muscles in the leg will extend and contract, thus bending the knees. It works in my head, anyways.

I think your Vet is daft...she needs to be seen now. If the bone is broken, it's an emergency situation. Depending upon where the break is, it is possible that she might be capable of bending it. If it's shattered then there are bone fragments that could be breaking off within the area...this is not a good thing! Remember a compound fracture will be poking OUT of the skin. A Jagged fracture, even if it's a "simple break" and not compound can sever tissue, tendons and other vital body parts IN the dog's body, that you and I can not see without x-rays...hence the need to have the dog seen as quickly as possible...what if MORE damage is being done while you've been told to wait? (that will add to the Vet Bill nicely!) For your Vet to have saddled YOU with the responsibility of keeping a dog "quiet" when the dog maybe in profound pain...is NOT good medicine. Most vets would advise you to go to an emergency clinic if they were so burdened as to not be able to see your dog ASAP as you could bring her in! I'm disturbed and pissed about this Vet...NOT at YOU. You may want to call another Vet or an emergency clinic and take this poor dog in NOW.