Robotic-assisted Unicompartmental Knee Arthroplasty: A Comparative Study of Image-based and Image-free Systems on Two-year Postoperative Complications and Costs.

Abstract

Background: Unicompartmental knee arthroplasty (UKA) is an increasingly popular surgical option, constituting approximately 10% of knee arthroplasty operations, with an anticipated upward trend. However, UKA presents technical challenges and higher revision rates compared to total knee arthroplasty (TKA). This study evaluates the outcomes and economic implications of using two robotic systems for UKA: the image-based (IBRA-UKA) and image-free (IFRA-UKA) robotic-assisted systems. We hypothesized that the image-free system, while incurring lower costs, would demonstrate clinical outcomes comparable to the image-based system.

Materials and methods: We conducted a retrospective study using the PearlDiver™ Database, selecting patients older than 40 years without previous knee surgeries who underwent robotic-assisted UKA (RA-UKA). Individuals with contralateral knee arthroplasty within 2 years were excluded. The procedures were divided into two cohorts, matched one-to-one for demographics and clinical characteristics. We compared 90-day, 1-year, and 2-year postoperative complications, along with cost analysis of preoperative computed tomography imaging and surgical expenses.

Results: A total of 2,490 patients were evaluated, with 1,245 in each cohort. No statistical differences were observed in postoperative complications, including revision rates, between the two cohorts. However, preoperative and surgical costs were significantly higher for the IBRA-UKA cohort compared to the IFRA-UKA cohort. Preoperative computed tomography scan costs averaged $916±$1,092 versus $0 (P<0.001), and surgical costs averaged $5,675±$9,436 versus $3,056±$5,419 (P<0.001).

Conclusion: The similar complication rates highlight the value of robotic technique in UKA regardless of system choice. However, the higher costs of IBRA-UKA raise financial concerns amid diminishing health care reimbursements. Further research is needed to evaluate robotic systems, focusing on intraoperative, postoperative, and functional outcomes.