Background and Objective: Patient-reported outcome measures after total knee replacement surgery have improved the evaluation of surgical effects on patients' quality of life. Various questionnaires have been used in different studies, with WOMAC and OKS being among the most common. The objective of this study was to assess the impact of total knee replacement surgery on the quality of life of patients aged 60 to 70 years with advanced osteoarthritis. Methods: This before-after cohort study without control group was conducted on 78 patients who underwent unilateral total knee replacement surgery. After recording the patients' demographic information in a checklist, the WOMAC and OKS questionnaires were completed for the patients, and the patients' quality of life scores, pain, joint stiffness, and physical function after surgery were evaluated compared to before. Results:Among the total samples, 44.9% were male, 21.8% had university education, 67.9% were urban residents, and 48.7% were employed. After surgery, the mean quality of life score based on OKS decreased from 21.97 before surgery to 36.74 after surgery. Pain scores decreased from 8.50 to 3.27, and joint stiffness scores decreased from 3.87 to 1.68. Additionally, the mean physical activity score significantly improved, increasing from 24.13 to 12.27. There was no significant difference in overall WOMAC scores and its subscales as well as OKS scores between men and women. Conclusion:The results showed that total knee replacement surgery significantly improves quality of life and reduces symptoms related to osteoarthritis in patients aged 60 to 70 years.