If it's that old then it has likely healed over. If the nail is still connected to live tissue then it may just set at that angle. As long as it doesn't seem to be causing pain or impeding movement then it shouldn't be an issue. The nail may eventually fall off but as long as the end of the finger is healed over that will minimize infection risk. They tend to be just fine with missing nails or toes as long as infection is kept at bay.