Bruising only takes effect if the player is attacked by wolves, bears, or falls down from a great height, and will increase the amount of Condition lost from afflictions that decrease condition. This includes other incidents if the bruising has not been treated. If the player avoids these circumstances, bruising does not affect the player.
To get rid of bruising, treat whatever condition caused the bruising, either the Laceration, Sprained ankle, or Sprained wrist that brought the condition on in the first place. Bruising doesn't have its own special condition to treat.