Specific Injuries (Optional Rule) (DMG)

The AD&D combat system does not call for specific wounds—scars, broken bones, missing limbs, and the like. And in most cases they shouldn't be applied. Remember that this is a game of heroic fantasy. If characters were to suffer real-life effects from all their battles and combats, they would quickly be some of the sorriest and most depressing characters in the campaign world.
It's hard to get excited when your character is recovering from a broken leg and a dislocated shoulder suffered in a fall off a 15-foot wall. It is not recommended that characters suffer specific injuries. In general, stick with the basic pool of hit points.
==Is This Injury Necessary?==
Before adding specific injuries to a campaign, consider all the factors. If the injury is one that can be healed, such as a broken arm, how long does this healing take? What are the effects on the character while the arm heals? Is there some quick way to get healed? Will the player still be able to have fun while his character is an invalid? Only after considering these questions satisfactorily should a specific injury be used.
DMs can use specific injuries to lessen a character's ability scores. A member of the party might acquire a prominent scar, lowering his Charisma by a point. Although, in this case, you'll want a ready explanation of why a scar had this effect, as in some instances a scar can actually enhance the personality of a person. It can make him look tougher, more mysterious, more worldly, more magnetic, all things that could conceivably increase a character's Charisma.
Similarly, the loss of a character's finger or eye could be used as an excuse to lower an excessively high Dexterity. Loss of an arm could reduce Strength (among other things).
Don't overdo this brute force approach to player control. Players get attached to their characters; they get used to thinking of them and role-playing them a particular way. Mess with this too much and you'll find players deserting your campaign.
Within reason, it's okay to leave a character physically marked. This leads to good role-playing. It adds to the feeling that each character is unique, making one player's fighter, wizard, or whatever different from all others. A scar here, an eye patch there, or a slight limp all result in more of an individual character and thus one more interesting to role-play.
But in these cases physical effects are tailoring the character, not punishing the player. Always try to be fair and ask the question, "Would I want to role-play such a character?" If the answer is no, then it's likely the player won't want to either. Don't load players with handicaps—their characters have enough of a challenge as it is.