I noticed this with the local ambulance service when I was a first responder. Femoral fractures were treated as a low priority by the system, but beause the local first responders were activated by voice (fairly informally) if there was going to be a long delay, the controller would send us around. I've sat with an elderly lady once for over an hour as she slowly descended into clinical shock. Fortunately the crew arrived just as I was on the phone to reprioritise this as a Cat A (using the magic phrase "altered consciousness"). In our local Mountain Rescue teams, femoral fractures are treated as life-threatening requiring immediate and rapid evacuation, preferably by helicopter. Reading the comments, any injury where the blood supply is compromised is also treated as the same priority - I suppose it's nice that we can use common sense when dealing with these.