To assess gender differences in the decision-making process for treatment of knee osteoarthritis (OA). A secondary analysis of a randomized trial was conducted (n = 193). Knowledge of OA and total knee replacement (TKR), decisional conflict, satisfaction with the decision-making process, treatment preference and TKR uptake 6 months later were compared by gender. Multivariate regression models were developed to identify gender-specific predictors. Women showed less knowledge (MD = -7.68, 95% CI: -13.9, -1.46, p = 0.016), reported less satisfaction (MD = -6.95, 95% CI: -11.7, -2.23, p = 0.004) and gave more importance to avoiding surgery (U = 2.09, p = 0.019). In women, more importance attributed to the time needed to relieve symptoms significantly reduced the odds of surgery (OR = 0.76, p = 0.016). The provision of information and/or promotion of shared decision-making could be of lower quality in female patients, although other explanations such as differences in information needs or preference for involvement in decision-making cannot be ruled out with the current evidence. Given the study's limitations, especially regarding the sample size, further confirmation is needed. A systematic, shared decision-making approach in consultation is needed to avoid potential gender-based biases.