Background Outcomes research in THA has focused largely on long-term implant survivorship as a primary outcome and emphasized the development of new implant technologies. In contrast, strategies to improve short-term outcomes, such as the frequencies of periprosthetic joint infections and unplanned readmissions, have received less attention. Questions/purposes We asked whether reductions in periprosthetic joint infections and early readmissions would have greater influence on the net monetary benefit (a summation of lifetime cost and quality of life) for THA compared with equivalent reductions in aseptic loosening. Methods A Markov model was created using decisionanalysis software with six health states and death to represent seven major potential outcomes of THA. We compared the effect of a 10% reduction in each of the following outcomes: (1) periprosthetic joint infection, (2) hospital readmission, and (3) aseptic loosening. Procedure costs (not charges) were derived from our hospital costaccounting system. Probabilities were derived primarily from the Australian Orthopaedic Association National Joint Replacement Registry, and utilities were estimated from a previous study at our institution using the time trade-off method. The primary outcome of the study is the net monetary benefit, which combines the reductions in cost and improvement in health-related quality of life in a single metric. Quality of life is expressed in quality-adjusted life years (QALYs), which are calculated by multiplying the utility of a health state (ranging from 0 to 1) by the duration of time in the health state. The cost and QALYs are reported separately as secondary outcomes. One-way and multivariate sensitivity analyses were performed including a probabilistic sensitivity analysis to account for uncertainty in model inputs. Results The net monetary benefit for a 10% reduction in periprosthetic joint infections was USD 278 (95% CI, USD 239-295) per index procedure compared with USD 174 (95% CI, USD 150-185) and USD 113 (95% CI, USD 94-129) for reductions in aseptic loosening and early readmission, respectively. Compared with the base case, reductions in cost associated with a 10% reduction in periprosthetic joint infections, early readmissions, and aseptic loosening were USD 98, USD 93, and USD 75 per index procedure, respectively. The increase in QALYs for One of the authors (KJB) certifies that he has received or may receive payments or benefits, during the study period, an amount less than USD 10,000 from Institute for Healthcare Improvement (Cambridge, MA, USA), less than USD 10,000 from Harvard Business School (Cambridge, MA, USA), and USD 10,000-USD 100,000 from Pacific Business Group on Health (San Francisco, CA, USA). All ICMJE Conflict of Interest Forms for authors and Clinical Orthopaedics and Related Research editors and board members are on file with the publication and can be viewed on request. Each author certifies that the institution where the work was performed approved the human protocol for this investigat...