dr. susan lewis is an orthopedic surgeon in sports medicine clinic and a failed transplant can cause additionale to the knee. >> if they fail, again you have this large piece of tissue flapping around in the knee and it doesn't tolerate very well. >> what is clear that the use of artificial knee replacement says surging as americans exercise longer and harder, more than half a million procedures are performed every year. his duggests that suggests thata successful transplant could provide relief for ten years allowing younger patients to postpone it until later in life. >> we think the future of joint replacement and future of joint care is on the by logic side, tissue side and plastic is very old. >> eric: still ahead. an n.f.l. player scores big in a san francisco neighborhood he grew up in. how he is giving back to his community.ededededededededededed >> eric: often the news in one san francisco neighborhood focuses on crime but there is plenty of things going on in bay view hunters point. a young man that is now an n.f.l. player giving back to his community. >> you see eric write at bay vie