In Motor Vehicle Collision Injuries, Larry Nordhoff describes how to use a tuning fork to diagnose a broken rib while on the scene of a nasty car accident. Besides the obvious phsycial examination, Nordhoff writes: "Place the vibrating tuning fork in a nonpainful site 3 to 4 inches away from the localized area having pain, and ask the patient whether he or she feels an increase in pain at the painful site or at the tip of the tuning fork."
If this causes more pain, this suggests there is a bone fracture and an x-ray is a good idea. But if there is no increased pain, then chances are very high there is no fracture. Head injuries are always something that should be looked at -you can live with a boken badly healed leg, but missed skull fractures the commensurate damage therein can be fatal - this is what killed Natahsa Richardson of the Redgrave family - a undiagnosed skull fracture she thought was "ok" but would have almost certainly been detected by the tuning form method.