Most EMT's are taught to check for crepitus during their secondary assessment (after checking more important stuff, like vital signs), especially in the pelvis. This occurs occasionally during trauma cases, though some EMTs will check for geriatric patients.

When the patient is supine, this is done by taking both hands (with gloves) and pressing downwards and forward towards the head. If there is a rice krispies sound, then You've got crepitus! The sound of the bones grinding against each other.

There is not much an EMT can do for it, other than not move the hips, and report it when you get to the hospital. If you're really on the ball you'll report it en route to the hospital and have an orthopedist standing by.