New technologies in hip and knee arthroplasty are commonly evaluated using cost-effectiveness analyses and similar economic assessments. There is a wide variation in the methodology of these studies, introducing the potential for bias. The purpose of this study was to evaluate associations between potential financial conflicts of interest (COI) and the outcomes of economic analyses. We hypothesized that authors’ COI and industry funding would be associated with conclusions favorable to a new technology. Economic analyses making cost-effectiveness or economic implementation claims on patient-specific instrumentation, robotics, and implants used in hip and knee arthroplasty published from 2010 to 2022 were identified. Papers were evaluated to determine if conclusions were favorable to the new technology being studied. Fisher’s exact test was utilized to determine the relationship between the presence of COI and an article’s conclusions. Of 43 eligible articles, 76.7% were cost-effectiveness analyses, 23.2% were cost analyses, and 67.4% of articles had conclusions favorable to a technology. Of the 29 articles with favorable conclusions, 26 had an author with a financial COI (89.7%), and 14 had industry funding (48.3%). Of the 33 articles with a financial COI, 26 (78.8%) had favorable conclusions, and of the 16 articles with industry funding, 14 (87.5%) had favorable conclusions. Fisher’s exact test revealed a statistically significant association between an article having favorable conclusions and the presence of an author’s COI or industry funding (odds ratio, 13.5; 95% CI confidence interval, 2.3 to 79.9; P = .003). Financial COIs were present in 79.1% of lower extremity arthroplasty economic analyses on technologies and were associated with an article having conclusions favorable to the new technology. Surgeons and decision-makers should be aware of the variability and assumptions in these studies and the potential bias of the conclusions.