My father, and another lady I know had great success with pulsed electromagnetic field therapy. In your friend's case, surgery sounds like the best option. Using the PEMF therapy both pre and post surgery, would drastically speed his healing time and decrease pain. If the joint has not totally deteriorated, there is a chance that PEMF therapy can eliminate the need for a replacement altogether.
Also, if he has fears about the surgery there is a very supportive group at Yahoo groups, total-joint-replacement.
For more info on PEMF therapy visit the website below.