Suggest Remedy To Fix Hole In Knee Cap

My boyfriend has a hole the size of a silver dollar in his knee cap. He had surgery almost a year ago and they put in a piece of bone from a cadaver. He went for an MRI last week and the doctor called him today and told him that the bone did7t take. My boyfriend is about to turn 37, and he is worried about what is going to have to be done for the pain to go away. What are some options to fix the hole in his knee cap other than a total knee replacement?