Knuckles

As one who has actually had this injury, it's worth asking yourself what story you are trying to tell with this prosthetic.  Are these busted knuckles supposed to have arisen from fighting?  If so, they aren't working.  When you fight, punching, the damage is concentrated on the first two knuckles: the tip of the first knuckle and the inside edge towards the first knuckle on the second.  Additional damage will tend to expand those focus points, ripping skin and dispersing blood liberally around the one-inch square covering the first two knuckles.  Injury will occur to the third and fourth fingers, but this tends to focus, next on the outside edge of the fourth knuckle (from glancing blows).  The third knuckle usually goes relatively unscathed.

So you should reduce considerably the effect on the third and fourth knuckles, move the second knuckle's damage to the left and the fourth knuckle's damage to the right.  Blood smear should go down the fingers more than it goes back along the top of the hand, and should focus between the first and second fingers.  Also don't neglect the thumb's second joint, which also tends to take a battering from glancing strikes.