Purpose: The aim of this study was to assess patients’ (and their families’) perceptions of the helpfulness of a decision making aid for osteoarthritis. Methods: This study was a national cross-sectional survey. Medical staff used an osteoarthritis patient decision aid (PDA) when conducting shared decisio making (SDM) with patients or their families who needed to make a decision. After the visit, we assessed the patient’s or their family’s perception of how useful the osteoarthritis PDA was (n = 330). Results: More than 80% of the respondents opined that the PDA was helpful in the consultation process. Among them, the patients who underwent no surgery were least prepared. Furthermore, those who were illiterate were significantly less prepared for decision making. Conclusions: Overall, using the PDA for SDM was positively perceived. In addition, SDM enables patients to discuss and reflect before making decisions. Approximately 30% of the population cannot make decisions immediately after the visit, but the PDA still helps them prepare for future decision making. In the future, we can develop the PDA to better meet the needs of users based on patient feedback. The reasons for why a patient does not undergo surgery can also be discussed.