gms | German Medical Science

Objectives: Primary robotic total knee arthroplasty (TKA) has been associated with favorable outcomes. To further characterize rTKA learning curve, our study evaluated early post-operative outcomes of robotics vs. manual primary TKA, based on surgeon experience.

Methods: Patients (> 64 years) from the Medicare claims database, with primary, unilateral, elective TKA ("index") from October 2015 to December 2019 were identified and categorized based robotic vs. manual surgery, and surgeon experience: low-count surgeons had performed < 40 cases in the 12-months pre-index; medium-low, medium-high and high count surgeons had performed 41-80, 81-120 or 121-160 cases. The low-count robotic cohort (RC) was compared to the low, medium-low, medium-high and high-count manual cohort (MC) for length of hospital stay (LOS), and rates of home and skilled nursing facility (SNF) discharge. Index- and 90-day payments associated with each patient cohort were also analysed. Descriptive statistics (means and proportion with 95% confidence intervals) were performed.

Results and conclusion: 296 low-count robotic cases were compared to 209,494 low-count manual and 252,905 medium-low, medium-high and high-count manual cases. The LOS for the low-count RC was 2.03 (95% confidence intervals (CI): 1.86-2.20) vs. 2.20 (95%CI: 2.20-2.21) for the low-volume MC. For patients within the medium-low, medium-high and high-count MC, LOS decreased to 2.03 (95%CI: 2.02-2.04), 1.87 (95%CI: 1.87-1.88) and 1.83 (95%CI: 1.82-1.85), respectively. In the low-count RC, 82.4% patients (95%CI: 78.1%-86.8%) were discharged home. In the MC, home discharge reached 74.2% (95%CI: 74.0%-74.4%) in the low-count cohort and increased to 83.6% (95%CI: 83.3%-84.0%) in the high-count cohort. Discharge to SNF was observed for 15.2% (95%CI: 11.1%-19.3%) in the low-count RC, vs. 21.0% (95%CI: 20.9%-21.2%) in the low-count MC. In the other MCs, SNF discharge declined from 17.6% (95%CI: 17.5%-17.8%) to 15.2% (95%CI: 14.9%-15.4%) and 13.4% (95%CI: 13.1%-13.7%) in the medium-low, medium-high and high-count cohorts. Index and 90-day payments for the low-volume RC averaged US$ 11,309 (95%CI: 10,806-11,812) and US$ 16,598 (95%CI: 15,664-17,533), respectively. The low-volume MC had index and 90-day payments averaging US$ 11,725 (95%CI: 11,710-11,740) and US$ 18,034 (95%CI: 17,991-18,078), respectively. The high-volume MC had index-and 90-day payments averaging US$ 11,251 (95%CI: 11,221-11,281) and US$ 16,101 (95%CI: 16,021-16,180), respectively. Patients operated with robotic surgery by surgeons with low yearly volume had a LOS and probability of home discharge similar to that of patients operated with manual surgery by high-volumesurgeons. Patients in the robotic group also had lower rate of SNF discharge compared to the patients in the manual surgery group, with surgeons of similar experience.