When a surgeon reassembles a patient’s broken bone with screws, I assume a pilot hole is required, lest the screw split the bone into which it’s being driven. Is it also necessary to run a tap into the pilot hole to cut threads, or are these screws typically self-tapping, like lag bolts for wood joints?
A barely related aside: a couple of years ago I was talking to my dentist and the subject of dental implants came up. This is where they permamently install a small metal stanchion into the jaw where a missing tooth used to be; after the bone has grown around its base and secured it, an artificial tooth can be bolted to the exposed top end of this stanchion. Anyway, my dentist showed me the tiny, tiny torque wrench that he uses to properly tighten the screws that hold that fake tooth on its mount. Cool stuff. 
Some are, some aren’t, AFAICT. The simplest look like ordinary wood screws, other even resemble sheet metal screws, and there are definitely self-tapping screw patents. And yes, if it’s not self-tapping, a pilot hole is used; this has a measurable effect on the strength of the join.
Looking at the x-rays of a person I know that fell down and elevator shaft, they are self tapping. No pictures for you as I keep this person’s privacy. They do look like deck screws of varying lengths. Some have threads the whole length some do not.
Is this a need-to-know-quick situation?
It depends on the application. Looks like for the most part, they are self-tapping, but not self-drilling.
Just as you can go into Home Depot and be faced with hundreds of options, there are different types of screws designed for orthopedic uses depending on whether you’re trying to reassemble a smashed foot or install a large joint replacement.
This pagegives a quick rundown of the thread types vs their purposes.