Becoming incapacitated by injury during a dream is fairly common, especially if you perceive yourself as operating out of a power deficit in waking life. Many times, people feel as though advantages lie outside themselves or with others, and see themselves as "handicapped."
The cause of the injury (means and inflictor) tells a lot about the significance of the injury as a dream symbol. If the wound is self inflicted or accidental, there may be a sense in which you are tripping yourself up by engaging in self-defeating behaviors. If the wound is inflicted by someone else and is intentional and malicious, others may be preventing you from reaching your potential. Of course the wound, its care, and the consequences from it also mean much. If you continue dreaming after the wound occurs, what are you unable to do that is normally classified as an "essential" activity?
Are you able to repel the attacker and treat the wound successfully?