OBJECTIVES: Predicting postoperative clinical outcomes from preoperative physical factors of patients undergoing total knee arthroplasty (TKA) would be useful. This study aimed to investigate the association between preoperative physical factors and postoperative outcomes. METHODS: This study included 119 patients. The preoperative physical factors and 1-year postoperative clinical outcomes were collected and assessed. Physical factors included age, sex, body mass index, skeletal mass index, knee range of motion, 5-m walk time, and Timed Up-and-Go (TUG) test result. Postoperative outcomes were evaluated using a sum of symptoms, pain, activities of daily living, and quality of life subscales of the Knee injury Osteoarthritis Outcome Score (KOOS-4), and the Oxford Knee Score (OKS). Correlation between physical factors and postoperative outcomes was analyzed by Spearman's rank correlation coefficient, and the association between physical factors and KOOS-4 or OKS was analyzed using multiple regression analysis. Receiver operating characteristic analysis was performed to calculate the cut-off value for the TUG test time associated with minimum postoperative OKS of 40. RESULTS: Among the preoperative physical factors, TUG test time showed significant correlation with OKS (ρ=-0.267), but none correlated with KOOS-4. Multiple regression analysis showed a significant association between TUG test time and OKS (95% confidence interval: -0.590 to -0.163) but not with KOOS-4. The cut-off value of preoperative TUG test time associated with minimum postoperative OKS of 40 was 12.96 s. CONCLUSIONS: Among the preoperative physical factors of patients undergoing TKA, the TUG test time was associated with clinical outcomes at 1 year after surgery.