[header] How to identify a broken femur [title] Notice sudden and severe pain. [step] When you break your femur, the pain will be sharp, pulsating and excruciating. When the femur is broken, the pain receptors send pain signals to the brain and pain is perceived. 
This is not the type of pain you might not notice, it is extreme and intense. [substeps] Especially consider pain that intensifies upon weight bearing activity and exercise and subsides with proper rest.