BACKGROUND: Research has indicated that early postoperative step counts are below the recommended levels for health-enhancing physical activity after total knee arthroplasty (TKA). This study aimed to evaluate the effects of preoperative individual characteristics, pain, physical function, and psychological factors on early postoperative physical activity, as measured by step counts, in 137 patients scheduled for TKA. METHODS: Patients were preoperatively assessed for individual characteristics (age, sex, body mass index, employment status, smoking and drinking habits, long-term care insurance), pain, range of motion, muscle strength, timed 10-m walk test performance, pain catastrophizing scale (PCS) scores (rumination, helplessness, and magnification), and pain self-efficacy. The daily step count was analyzed 4 weeks postoperatively. Multivariate regression analysis was performed to analyze the relationships between postoperative step counts and individual characteristics, pain, physical function, and psychological factors. RESULTS: Step counts were significantly influenced by preoperative PCS magnification scores (β= -0.31, p= 0.01) and the category of long-term care insurance (β= -0.24, p= 0.02). CONCLUSIONS Preoperative evaluation of the long-term care insurance category and PCS magnification score may aid in predicting early postoperative step counts in patients receiving TKA, which may, in turn, improve clinical management during the early stages of treatment.