Robotic-arm-assisted Knee Arthroplasty Associated With Favorable In-hospital Metrics and Exponentially Rising Adoption Compared With Manual Knee Arthroplasty

Background: Technology-assisted knee arthroplasty (KA), including robotic-arm-assisted knee arthroplasty (RA-KA) and computer-assisted (CA-KA) knee arthroplasty, was developed to improve surgical accuracy of implant positioning and alignment, which may influence implant stability, longevity, and functional outcomes. However, despite increased adoption over the past decade; its value is still to be determined. Questions/Purpose: This study aimed to compare robotic-arm (RA)-KA, CA-KA, and manual (M)-KA regarding (1) in-hospital metrics (length of stay [LOS], discharge disposition, in-hospital complications, and hospitalization-episode costs), (2) characterize annual utilization trends, and (3) future RA-KA and CA-KA utilization projections. Methods: National Inpatient Sample was queried for primary KAs (unicompartmental/total; 2008 to 2018). KAs were classified by modality (M-KA/CA-KA/RA-KA) using International Classification of Disease-9/10 codes. A propensity score-matched comparison of LOS, discharge disposition, in-hospital complications (implant-related mechanical or procedure-related nonmechanical complications), and costs was conducted. Trends and projected utilization rates were estimated. Results: After propensity score matched to their respective M-KA cohorts, RA-KA and CA-KA exhibited shorter LOS(RA-KA versus M-KA: 2.0 +/- 1.4 days versus 2.5 +/- 1.8 days; P < 0.001; CA-KA versus M-KA: 2.7 +/- 1.4 days versus 2.9 +/- 1.6 days; P < 0.001) and in-hospital implant-related mechanical complications (P < 0.05, each). RA-KA demonstrated lower nonhome discharge (P < 0.001) and in-hospital procedure-related nonmechanical complications (P = 0.005). RA-KA had lower in-hospital costs ($16,881 +/- 7,085 versus $17,320 +/- 12,820; P < 0.001), whereas CA-KA exhibited higher costs ($18,411 +/- 7,783 versus $17,716 +/- 8,451; P < 0.001). RA-KA utilization increased from <0.1% in 2008 to 4.3% in 2018. CA-KA utilization rose temporarily to 6.2% in 2014, then declined to pre-2010 levels in 2018 (4.5%). Projections indicate that RA-KA and CA-KA will represent 49.9% (95% confidence interval, 41.1 to 59.9) and 6.2% (95% confidence interval, 5.3% to 7.2%) of KAs by 2030. Discussion: RA-KA may provide value through improving in-hospital metrics and mitigating net costs. Similar advantages may not be reliably attainable with CA-RA. Because RA-KA is projected to reach half of all knee arthroplasties done in the United States by 2030, further cost analyses and long-term studies are warranted.