Sprain or bone crack

During one of my trauma class last week, we discuss about sprain. Then somehow a question came across my mind. here was the question:

If we're working in a rural hospital without Xray, or any other kind of modern technologies and equipment, and one day a patient came complaining that he had hurt his ankle. (not bleeding or wound, just bend or hit something etc). How then are we suppose to know whether is it a sprain or is it a crack in the bone (not displaced fractures, just crack) without the help of X ray.

There are answer like refer patient to a bigger hospital with X ray ( but what if the patient is not willing to go so far for some reason). well yes we can apply the RICE method and prescribe some pain killer.

R-rest
I- ice application
C- compression
E- elevation of affected part

but what i really want to know is that whether is there a way to differentiate a sprain and a bone crack just by general examination and palpation etc without using x ray or other modern techniques.

So feel free to comment on any ways to differentiate these 2 problems. thanks.