Oh, what's the injury in question? About two months ago I stepped on one of the lego refrigerator magnets that C had scattered on the floor, barefoot. It apparently did something interesting to my big toe, because it started hurting like a very painful thing every time I put pressure on it, even though the toe wasn't where I'd stepped. Then it mostly stopped being agonizing and became painful with occasional pins-and-needles and numbness. After about a month I mentioned it to my doctor, who poked and prodded, diagnosed some kind of nerve compression and said, "stay off it".
After we both had a hearty laugh she prescribed the crutches as a way of saying, "No, really. Stay off it." And they do seem to help. (Oh, and aluminum crutches suck. They're lighter than wood, but all the adjusting pins have play in them, so there's a bunch of clicking noises when you walk. I've wrapped the handles in tape, and plan to squirt glue or caulk into the legs. Because it's just annoying.)