There are 3 types of injury.
1) Minor scrapes and bruises that do not affect the character's ability.
2) Major injuries that would harm the wounded's fighting ability but would not necessarily kill them quickly (broken bones, long limb cuts)
3) Fatal wounds that kill people deas
D&D only has rules for 1 and 3. Type 1 wounds are associated with HP loss. HP damage is minor scrapes and bridles that have no almost real effect on the target. When a character hits negatives, they have been stuck with either too many Type 1s than they could handle OR a Type 3 wound.
It they die, it was a Type 3.
If they don't, the injury could have been a Type 1 that was healed naturally or 3 healed magically.
But there are no Type 2 injuries in D&D 4ed. There are no rules for hindering, long lasting, nonfatal but threatening injuries.
The point is that a character doesn't get wounds and injuries they have to worry about until they are almost dead. When a character gets a major wound in D&D, they will need magic or professional medical care or they are DEAD.