Loss of sensation at the end of the extremity. Numbness or tingling sensations. Involuntary muscle spasms. Other unusual pain, such as intense pain in the rib cage when a patient takes a deep breath or coughs. If you discover any of these symptoms and cannot attribute them to any other obvious cause, assume them to be symptomatic of a fracture.
Few fractures are life threatening unless mishandled.
Check the patient for any more serious injuries. Ensure your patient is breathing and that excessive bleeding is controlled and that all open wounds are protected as best you can from contamination. After these elements are satisfied you can deal with stabilization of the fracture. If you can, carefully cut away all clothing near the fracture site. You need to make sure the fracture hasn't broken the skin and you may be able to use the cut away material to aid in splinting.