Demographic, baseline and follow-up data from the "Decision 2" trial. 556 participants aged over 45 years with activity-related knee joint pain. Participants were randomized to a control condition, where they received currently available osteoarthritis information with pathoanatomical content or an experimental condition, where they received the same osteoarthritis information but without pathoanatomical content. Primary outcomes were participants' beliefs about the need for x-ray to confirm diagnosis and joint replacement surgery in the future. All data presented in the results paper (J Orthop Sports Phys Ther. 2023;53(4):1-15) available in XLSX format.