Introduction : Inflammatory arthritis, particularly RA, can lead to significant joint destruction and functional impairment, necessitating interventions such as TKA. Despite medical therapy, severe joint damage may occur, warranting surgical intervention. This study assesses the functional outcomes post-TKA in patients having inflammatory arthritis. Materials and Methods: Patients who received TKA for inflammatory arthritis were included in this prospective observational cohort research, specifically RA, between 2019 and 2023 at Saveetha Medical College, Chennai. Clinical, radiological, and functional results have been assessed using the American Knee Society scoring system. IBM SPSS version 22.0 was utilized for analysis of data, p < 0.05 is the threshold for statistical significance. Results:Twenty TKAs have been performed for RA, with all patients successfully followed up. The mean age of the patients was 58.5 years, and the majority were female. Before TKA, the average length of RA was 7.24 years, and all patients were in stage IV illness. Preoperative and postoperative knee society scores showed significant improvement, with average scores of 58.15 and 96.15, respectively. Functional scores also demonstrated substantial enhancement post-TKA, with an average increase of 130%. Radiological assessment revealed no evidence of lysis in any patient. Conclusion: Significant inverse relationship among the postoperative functional score and the length of the disease and the involvement of other joints. Utilizing the American Knee Society and functional scoring systems allows for objective prediction of surgical success. This can motivate surgeons and treating physicians to enhance care for RA patients.