Impact of robotic assistance on hospital stay direct costs of total knee arthroplasty.

Robotic-assisted total knee arthroplasty (RA-TKA) aims to improve outcomes and reduce costs, but its effect on in-hospital direct costs remains unclear. This study compares in-hospital direct costs between RA-TKA and conventional TKA (C-TKA). A retrospective review of elective TKAs from 1/2018-5/2023 at a single center was performed. RA-TKA and C-TKA patients were matched by demographics and surgery date. Cost metrics included total, fixed, variable direct costs and indirect costs. Operative times, length of stay (LOS), and in-hospital costs were compared using independent t-tests, Mann-Whitney U, and Chi-square tests. Pearson correlations assessed relationships between costs and clinical metrics. A hierarchical multilinear model was used to control for demographics, operative time, and LOS to isolate the cost of robotic assistance. Of 2590 primary TKAs, 440 used robotic assistance. After matching, 788 patients remained (397 RA-TKA, 391 C-TKA). Preoperative Knee Injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS JR) and Veterans Rand 12 Item Health Survey (VR-12) scores were similar. RA-TKAs had longer operative times ("cut-to-close": 128 vs. 110 min; "room-in to room-out": 202 vs. 182 min; p < 0.001) and longer LOS (2.39 vs. 1.56 days; p < 0.001). RA-TKAs had 17.8% higher total direct costs and 18.5% higher variable direct costs (p < 0.001). After adjusting for operative time and LOS, robotic assistance independently increased total direct cost by 4.2% of median C-TKA cost (p < 0.001). Robotics remained an independent predictor of total and variable direct cost (p < 0.001). RA-TKA incurs higher in-hospital direct costs than C-TKA, largely due to increased variable costs. Even after adjusting for operative time and LOS, robotic assistance independently contributes to higher total direct cost.