I was dogsitting a wonderful boy named Archie. I wanted to take one of my girls to the vet for an eye check and bring everyone along. Archie loved car rides. So I shuffle everyone into the garage and go to lift the tailgate of the SUV when Archie jumped. The tailgate wasn't open yet. He bounced off and fell. It was a short fall. Just a couple of feet. But a very poor angle and he shattered his elbow.
He lost his leg. No OS.
That was 2 yrs ago. Once past the trauma he returned to his normal self. He loves running around my back yard chasing chickens. He's learned that he can't chase my girls when they are in full run, but is able to join in at his own speed. He can do 5 steps without issue but does prefer the ramp I have (I made it when my Diamond had OS, years ago). The only thing different is that he is hesitant about not carpeted floors now. He'll still do them, but prefers the runners.
It doesn't necessarily mean OS. And even if he loses his leg, he'll be fine. The first two weeks are the worst. Hold on. It gets much much much better.