Cost Analysis of Conversion Total Knee Arthroplasty

Abstract

Background: Total knee arthroplasty (TKA) after prior knee surgery, also known as conversion TKA (convTKA), has been associated with higher complications, resource utilization, time, and effort. The increased surgical complexity of convTKA may not be reflected by the relative value units (RVUs) assigned under the current U.S. coding guidelines. The purpose of this study was to compare the RVUs of primary TKA and convTKA and to calculate the RVU per minute to account for work effort. Methods: The American College of Surgeons National Surgical Quality Improvement Project (NSQIP) database was analyzed for the years 2005 to 2020. Current Procedural Terminology (CPT) code 27447 alone was used to identify patients who underwent primary TKA, and 27447 plus 20680 were used to identify convTKA. After 1:1 propensity score matching, 1,600 cases were assigned to each cohort. The 2023 Medicare Physician Fee Schedule RVU-to-dollar conversion factor from the U.S. Centers for Medicare & Medicaid Services (CMS) was used to calculate RVU dollar valuations per operative time. Complication rates were compared using a multivariate logistic regression model controlling for baseline characteristics. Results: The mean operative time for TKA was 97.8 minutes, with a corresponding RVU per minute of 0.25, while the mean operative time for convTKA was 124.3 minutes, with an RVU per minute of 0.19 (p < 0.0001). Using the conversion factor of $33.06 per RVU, this equated to $8.11 per minute for TKA versus $6.39 per minute for convTKA. ConvTKA was associated with higher overall complication (10.9% versus 6.5%, p < 0.0001), blood transfusion (6.6% versus 3.7%, p < 0.01), reoperation (2.3% versus 0.94%, p < 0.0001), and readmission (3.7% versus 1.8%, p < 0.001) rates. Conclusions: The current billing guidelines lead to lower compensation for convTKA despite its increased complexity. The longer operative time, higher complication rate, and increased resource utilization may incentivize providers to avoid performing this operation. CPT code revaluation is warranted to reflect the time and effort associated with this procedure. Level of Evidence: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.