Bilateral Total Knee Arthroplasty Should Remain the Exception and Not the Rule

Abstract

Commentary Transparent shared decision-making is the recommendation by Warren et al. in their article. The authors call on surgeons to make patients aware of the increased risk of complications with bilateral total knee arthroplasty (TKA) regardless of the degree of baseline health. Such a response might not be enough. Warren et al. used the American College of Surgeons (ACS) National Surgical Quality Improvement Program (NSQIP) database to capture patients undergoing bilateral total knee arthroplasty (TKA) and then captured their ACS Morbidity Probability variable, which is derived from an extensive number of comorbidities and risk factors. These patients were matched to those undergoing unilateral TKA. Both groups of patients were stratified into 4 different levels of risk, and complication rates were compared within each level. The patients who underwent bilateral TKA had a higher complication rate regardless of the preoperative risk level. The authors admit the limitations of their study; the NSQIP is limited to 30-day follow-up, and defining bilateral procedures requires certain assumptions. Nonetheless, their reported incidence of bilateral TKA is supported by the 3.9% rate in Part A Medicare data1, and their methods are applied the same across all 4 stratifications of risk. Their findings refute previous studies that concluded that younger and healthier patients undergoing bilateral TKA have no higher risk of complications than those undergoing unilateral procedures. Simultaneous bilateral TKA is attractive to patients and surgeons for many reasons. The overall time in recovery is condensed and costs are reduced. Previous authors have demonstrated equal outcomes, but even advocates of the practice have noted increased rates of complications that led to the eventual working paradigm that it be reserved for younger patients with less risk2,3. This article is the first to examine that assumption with a robust model consisting of 4 levels of risk derived from multiple elements. The greater than threefold higher risk of complications even in the lowest risk level is derived from registry data across multiple hospitals. A bias toward reporting of positive outcomes is inevitable in published case series, which might not capture the true distribution of the complications. The added overall risk reported is compatible with other recent data-mining studies that show the same effect without the stratification of comorbidities4,5. Surgeons are inherently biased in terms of how they interpret the literature relative to their perception of their personal surgical outcomes. Complications after TKA are relatively rare and can occur sporadically, leaving the individual surgeon in a “prison of small numbers” that can lead to undue confidence recommending bilateral TKA. This report, based on data across multiple practices and thousands of patients, requires sober study by all surgeons. All surgeons are instinctively and correctly uncomfortable with cases with longer anesthesia times and wound exposure times, which are inherent to bilateral TKA. Most surgeons are aware of the increased risks of needing transfusion and needing a skilled nursing facility after discharge. Dorr et al. demonstrated the synergistic added impact of fat embolism in bilateral procedures >30 years ago6. However, surgeon perceptions of added risk are muted by self-confidence, trust in local protocols, and the desire to satisfy patient preferences for bilateral procedures. Surgeons are painfully aware of the difficulties and interruption of normal life that patients incur when undergoing complications from TKA. Patients are at risk for discounting warnings about complications unless they have sustained such complications themselves or observed family and/or friends experience them. Shared decision-making is an improvement over paternalistic direction from a surgeon, but it still allows for preconceived assumptions by the surgeon and patient in an unequal relationship of knowledge and personal experience. Given the reported added risk inherent to bilateral TKA that is shown in this article, even in the healthiest patients, is it enough for the surgeon to make that risk transparent to the patient, especially if the risk is discounted by the patient because of the time and economic concerns that cloud his or her choices? All surgeons should carefully study the added risks reported in this study when bilateral TKA is pursued rather than staged TKA. Further studies will be needed to support the frequently given assumption that patient selection neutralizes such added risk; at this time, evidence for such a counterargument is weak. Providing transparency about added risk does not reduce the increased incidence of complications. One of the basic tenets of medicine is primum non nocere (first do no harm); an argument can be made that bilateral TKA should be performed relatively rarely and surgeons should be more resistant to acquiescing to patient expectations.