147 patients with advanced knee or hip osteoarthritis (OA) were randomized to undergo a booklet + videodisc program or a booklet-alone program, to compare these two patient decision aids with respect to patient knowledge, decision-marking participation, satisfaction, and treatment preference. Results indicated that, although both interventions had positive effects on patient knowledge and willingness to participate in treatment decisions, the addition of a videodisc to a booklet did not improve these outcomes further. In addition, the patient decision aids used in this trial did not have a significant effect on certain ethnic groups more than others.