Background/Purpose: Approximately 4% of total knee replacement (TKR) patients require revision within five years. Blacks are 40% more likely to undergo TKR revision than whites,¹ but whether racial disparities exist for both septic and aseptic TKR revision risk is unknown.

Methods: This study used patient-level data from four diverse states representing the Northeast (NY), Southwest (AZ), South (AR), and Gulf Coast (FL) with ≥ 5 years of revisit files available from the Healthcare Utilization Project State Inpatient Databases (HCUP-SID) and New York Statewide Planning and Research Cooperative System (SPARCS). The index cohort was defined as black or white patients undergoing their first primary TKR. The reason for TKR revision was determined using ICD-9-CM diagnosis codes and categorized as septic, fracture, mechanical (“aseptic”) or other.  Kaplan-Meier survival curves were generated to assess the association between race and time to septic or aseptic TKR revision. Cox proportional hazards models were used to evaluate the association between demographic and clinical characteristics and septic or aseptic TKR revision.

Results: We identified 607,798 patients who underwent primary TKR. Mean (SD) age was 67 (10) years, 63% were female and 8.9% were black. Compared to whites, blacks were younger, more likely to be female, to have diabetes, obesity, renal disease and inflammatory arthritis, to have experienced a surgical complication during the index TKR, and to have Medicaid insurance (p< 0.001 for all). Median [IQR] duration of surveillance was 5.25 [2.25, 8.75] years.  26,268 (4.3%) of the patients underwent TKR revision, 1.3% septic, 0.1% fracture, 2.6% mechanical (“aseptic”) and 0.3% other.  In univariate analysis, the risk of septic revision was higher in blacks than whites, HR 1.4 (95% CI 1.3-1.5) (Figure 1a), as was the risk of aseptic revision, HR 1.7 (95% CI 1.6- 1.8) (Figure 1b). In multivariable models, the increased risk of TKR revision in blacks compared to whites was attenuated, but still present; HR 1.2, 95% CI 1.1-1.3 for septic and HR 1.3, 95% CI 1.3-1.4 for aseptic revision respectively (Table 1).  In these models, Medicaid insurance was a risk factor for septic TKR revision (HR 1.3; 95% CI 1.2-1.5) but not aseptic TKR revision (HR 0.9; 95% CI 0.8-1.0) (Table 1).

Conclusion: Blacks are at higher risk of both septic and aseptic TKR revision than whites.  Medicaid insurance, a proxy for poverty, is associated with a higher risk of septic but not aseptic TKR revision. The interaction between race and poverty on the risk of septic TKR warrants study.

¹Bass, AR et al. Higher Knee Arthroplasty Revision Rates among U.S. Blacks: A Systematic Literature Review and Meta-Analysis J Bone Joint Surg (Am) 2016; 98(24):2103-2108.

HKUP KM curves.4

Table 1 HCUP.5

« Back to 2019 ACR/ARP Annual Meeting

ACR Meeting Abstracts - https://acrabstracts.org/abstract/racial-disparities-in-septic-and-aseptic-total-knee-replacement-revision-risk-a-study-using-four-state-wide-inpatient-databases/