Robotic-assisted total hip arthroplasty in the United States: a nationwide propensity-matched analysis of adoption, outcomes, and complications

Robotic assisted total hip arthroplasty (RA-THA) has been introduced to improve the precision of implant positioning and potentially enhance outcomes in THA. However, large scale national data on its real-world impact are lacking. This study presents the first nationwide analysis of RA-THA using the National Inpatient Sample (NIS), evaluating trends in adoption and comparing perioperative outcomes between RA-THA and conventional THA. We performed a retrospective cohort study using the NIS (2016–2022). Adult patients undergoing primary elective THA were identified, and those with robotic assistance were classified using ICD-10 procedural codes for robot-assisted surgery. Propensity score matching (1:1) was employed to create comparable cohorts of RA-THA vs. conventional THA, controlling for patient demographics, hospital characteristics, and comorbidities. Temporal trends in RA-THA utilization were assessed. Outcomes included length of stay (LOS), hospital charges, and in-hospital complications. Matched outcomes were compared with appropriate statistical tests, and relative risks (RR) of specific complications were analyzed. A total 1.9 million THA cases were identified nationwide, of which 2.9% involved robotic assistance. RA-THA utilization increased significantly over the study period (from 1.2% in 2016 to 6.7% in 2022, P < 0.01). In unmatched comparisons, patients undergoing RA-THA were slightly younger on average and more frequently treated at urban teaching hospitals than those with conventional THA. After propensity matching RA-THA was associated with a shorter mean LOS (by 0.7 days) and higher mean hospital charges (by 10,000$~, P < 0.01). The matched RA-THA cohort had a significantly lower overall complication rate compared to matched conventional. In particular, non-robotic THA patients had higher risks of transfusion, in-hospital prosthetic complications, and venous thromboembolism. A forest plot of matched outcomes demonstrated that conventional THA carried elevated RRs for multiple postoperative complications relative to RA-THA (RR > 1 favoring RA-THA for most complication endpoints). In this first nationwide analysis of RA-THA, we found that robotic assistance, while still used in a minority of THA cases, grew steadily in adoption through 2022. RA-THA was associated with shorter hospital stays and a reduced risk of in-hospital complications compared to conventional THA, with higher hospitalization costs. These findings suggest that RA-THA can confer perioperative benefits in routine practice, though its economic impact and long-term clinical advantages remain areas for further investigation. Levels of Evidence: LEVEL III.