en Orthopedic Surgery Orthopedic Surgery Original Research Original Research <p> <strong>Abstract </strong></p><p> <strong>Background:</strong> In the recent decade, many primary total knee arthroplasties have </p><p> been carried out in Iran and the number of revision cases is expected to rise with the </p><p> aging population. The aim of this study was to report the outcome of revision surgery </p><p> in the country and make a comparison between the outcome of revision and that of </p><p> the primary arthroplasty. </p><p> <strong>Methods:</strong> Retrospectively, each case of 19 consecutive revision total knee arthroplasties was matched individually with two cases of primary total knee arthroplasty </p><p> based on gender and age (within 5 years) in order to compare the outcome in the two </p><p> groups of revision and primary arthroplasties. Detailed demographic data, underlying </p><p> diagnosis, patient-reported pain severity, and Knee Society score were recorded </p><p> pre-operatively and in the third month after the surgery for each patient in the two </p><p> groups. Using chi-square, fisher's exact, one-way ANOVA, independent, and paired </p><p> t-tests, we compared the outcomes in two groups as well as in each group before and </p><p> after the arthroplasty. </p><p> <strong>Results:</strong> Knee pain was significantly decreased after the surgery in the two groups </p><p> of revision (p = 0.031) and the primary (p < 0.001) arthroplasty. There was no statistically notable difference of post-operative pain between the two groups of revision </p><p> and primary TKA. The Knee Society score remarkably increased in both groups after </p><p> the surgery (both ps < 0.001). The differences of Knee Society scores before and after </p><p> the surgery were calculated separately in each group and compared to show that the </p><p> primary group had a better outcome (p < 0.001) rather than the revision arthroplasty </p><p> group. </p><p> <strong>Conclusion:</strong> Conclusion: Satisfactory outcomes were obtained in our revision total </p><p> knee arthroplasties however, the primary arthroplasties had better results. The results </p><p> of surgery appear to be closely related to the technical demands placed on surgeon. </p><p> Because we have to deal with more cases of revision total knee arthroplasty in </p><p> near future, more comprehensive risk factor assessment studies with large sample </p><p> size are required for gaining better results.</p><p>  </p><p>  </p><p>  </p> revision total knee arthroplasty, primary total knee arthroplasty, knee 1 7 http://mjiri.iums.ac.ir/browse.php?a_code=A-10-1-32&slc_lang=en&sid=1 Hossein Farahini 20031947532846001740 20031947532846001740 No Rasool-e-Akram General Hospital.Iran Universityof Medical Sciences. Ehsan Akbarian eakbarian@gmail.com. 20031947532846001741 20031947532846001741 Yes Shahid Beheshti University of Medical Sciences Mehdi Moghtadaei 20031947532846001742 20031947532846001742 No Rasool-e-Akram General Hospital.Iran Universityof Medical Sciences. Siroos Malekpoor 20031947532846001743 20031947532846001743 No Rasool-e-Akram General Hospital.Iran Universityof Medical Sciences.