Referring to the US only-- I assume other nations were the same,but I have no specific knowledge. Yes, "non-combat injuries" such as you mention were seen as unavoidable at times. Soldiers who were injured were treated as well as possible given medical support in their location, and if not treatable or returnable to duty were evacuated through the medical chain just as were soldiers wounded by the enemy. They were treated by the same medical system, and by the same personnel, as were soldiers wounded in action. No separate hospitals were set up to treat solely "non-combat" injuries-- this would have been a true waste of scarce resources. When these non-combat injuries were healed, the soldiers could be returned to the fighting forces, or if they had a permanent disability or needed prolonged treatment, they could be evacuated to the United States and eventually discharged for physical disability-- again just like those wounded in action. You mention the one distinction between the two wounding patterns-- The Purple Heart is officially only given for wounds received in combat as a result of enemy action. Thus, falling off a truck and breaking your leg would not generally be grounds for getting a Purple Heart, while getting shot in the leg would be. I am sure that some Purple Hearts were awarded for what most of us would consider to be "non-enemy action" injuries, but those would have been done either in error or in borderline cases where direct enemy action might have been construed to have caused the soldier to become injured, without being hit by bullets, fragments, etc.