Comparative Analysis of Hospital Length of Stay and Discharge Status of Two Contemporary Primary Total Knee Systems

This study compares the differences in hospital length of stay (LOS), operating room time (ORT), discharge status, and total hospital costs among primary total knee arthroplasty (TKA) patients implanted with one of two contemporary primary total knee systems. A retrospective cohort analysis of elective inpatient, primary, unilateral TKA patients in the United States from 2013 to 2014 was conducted using the Premier Perspective (R) hospital billing database. The included patients had a diagnosis for osteoarthritis and received an ATTUNE (R) Knee (Gradually Reducing Radius Knee) or Triathlon (Single Radius Knee) from a hospital where both devices were used. Patient, provider, and procedure characteristics were included in generalized estimating equation (GEE) models to explore the impact of device on LOS, ORT, discharge status, and costs accounting for clustering within hospitals. A 1:1 propensity score-matched sensitivity analysis was also conducted. There were 1,178 patients who received gradually reducing radius knee and 5,707 patients who received single radius knee. GEE models indicated that the adjusted mean LOS and ORT for patients who received gradually reducing radius knee were significantly shorter than those who received single radius knee (p < 0.001). The adjusted odds ratios for gradually reducing radius knee patients being discharged to a skilled nursing facility (SNF) or other facility were 39% lower than that for single radius knee patients (odds ratio = 0.61; 95% confidence interval: 0.50-0.75; p < 0.001). The adjusted mean costs for gradually reducing radius knee patients were significantly lower than the single radius knee patients ($12,824 [1,813] vs. $18,713 [1,505]; p < 0.01). Findings were similar in the propensity-matched cohort of 2,044 patients, which was balanced on baseline covariates between devices (standardized differences were 8%). Patients who received gradually reducing radius knee had a shorter LOS and ORT, were less likely to be discharged to a SNF or other facility, and had lower total hospital cost than those who received single radius knee. These outcomes are increasingly relevant as hospitals bear the financial burden for episodes of care, and will require optimization to achieve success under the Centers for Medicare and Medicaid Services' Comprehensive Care for Joint Replacement model.