For those who want to know, a DIP joint is the Distal Inter Phalangeal joint which is the end joint. The middle joint is the PIP joint (Proximal Inter Phalangeal) which lends itself to joint replacement much more easily. I've many years experience in this kind of surgery and I can tell you without reservation that the DIP joint is never going to be suitable for a joint replacement. Bear in mind that the distal phalangeal bones are minute, about the size of a bone out of the tip of a chicken wing, so working on it to received such an implant would be pretty near impossible. Even a silastic implant would be unlikely to be very successful. So the suggestion of a fusion is by far the best remedy for this situation.