Is Simultaneous Bilateral TKA as Safe as Staged Bilateral TKA?

    The authors examine the literature on VTEs and other complications following bilateral total knee arthroplasty, with the goal of establishing an institution-wide set of criteria for performing simultaneous bilateral procedures.


    Daniel C. Smith, MD, and Jonathan M. Vigdorchik, MD


    The authors have no disclosures relevant to this article.


    When a patient seeks surgical treatment for bilateral knee osteoarthritis (OA), deciding whether to perform a simultaneous or a staged bilateral total knee arthroplasty (TKA) is often driven by a combination of patient characteristics and surgeon preference. Unfortunately, there is a lack of clarity regarding evidence-based indications and outcomes of simultaneous versus staged bilateral TKA.

    Approximately 6% of patients with bilateral knee OA will undergo a staged BTKA, while 10% of patients undergoing unilateral TKA will seek surgery on the contralateral knee within a year. Thus, decision-making criteria to help guide the treatment of patients with bilateral knee OA would be beneficial. [1,2]

    With the potential benefits of simultaneous bilateral TKA in mind, and considering the potential negative consequences of the procedure, we have established criteria for simultaneous bilateral TKA within our institution, as outlined in Table 1.

    Table 1. Exclusion Criteria for Bilateral TKA

    Age > 75 years

    ASA 3 or 4

    Ischemic heart disease (positive stress test)

    On aggressive anticoagulation or clopidogrel (Plavix)

    Poor ventricular function (LVEF < 50%)

    Oxygen-dependent pulmonary disease

    Renal insufficiency or end-stage renal disease, Cr > 1.6

    Steroid-dependent asthma or COPD

    Pulmonary hypertension (PAP>45)

    Morbidly obese, BMI 40 or more

    Chronic liver disease (Childs class B or worse)

    Cerebral vascular disease

    Sleep study-proven obstructive sleep apnea without treatment, or STOP/BANG >5

    Insulin-dependent diabetes mellitus, blood glucose > 180

    History of DVT or PE

    History of congestive heart failure

    Hemoglobin < 11 or Jehovah’s Witness


    As recommended elsewhere, we also note that any patient with a history of right heart strain or pulmonary hypertension should undergo echocardiography prior to consideration for simultaneous bilateral TKA. Following exclusion by the criteria in Table 1 or positive echocardiography, patients are then assessed by an anesthesiologist in preoperative testing prior to the day of planned surgery.

    If a patient is cleared to undergo simultaneous bilateral TKA and the surgeon’s preference is to use a tourniquet, all attempts are made to minimize the end-organ embolic burden of tourniquet release. This is done by performing the contralateral TKA without tourniquet or by delaying tourniquet inflation on the contralateral TKA until the tourniquet is released on the first knee.

    Is Staged Bilateral TKA 1 Event or 2?

    Comparing the safety of unilateral TKA with that of bilateral TKA is difficult given the many biases inherent in previous studies [2].

    The first step in making such comparisons involves setting a uniform period of time between staged surgeries, as staged bilateral TKA may be performed within the same hospitalization or on separate hospitalizations.

    Much of the available literature utilizes a 3-month window between staged bilateral TKA events. This time frame was in part determined by insurance payers, but also derives from the tradition of imposing a delay between surgical events to prevent a “second-hit” to the patient, which could increase the risk for venous thromboembolism (VTE). [3]

    Even with recognition of the 3-month delay within staged bilateral TKA, many studies comparing patient outcomes treat the surgeries as separate unilateral TKAs rather than as a staged bilateral TKA, evaluating the outcomes of each unilateral TKA separately.

    Thus, given these biases, staged bilateral TKA would appear to be a safer alternative to simultaneous bilateral TKA if the 2 procedures were taken as singular events.

    No Difference in Rates of VTEs, Transfusions, Infections

    A different picture begins to emerge, however, when assessing the safety of simultaneous bilateral TKA in comparison with staged bilateral TKA taken as the accumulation of 2 operative courses. Although historic studies have quoted VTE rates following simultaneous bilateral TKA at 1.4%, more recent studies suggest the rate has decreased to 0.3%, which is comparable to unilateral TKA. [3]

    This lack of significant difference in VTE rates has been replicated in other studies, in which it was also demonstrated that the total blood loss associated with simultaneous bilateral TKA was not statistically significantly different from the blood loss of each separate unilateral TKA of a staged procedure. [4]

    Additionally, Niki et al [4] found no statistical differences in transfusion rates, with much of the improvement attributed to the now routine use of tranexamic acid. While the authors also noted an elevation in the erythrocyte sedimentation rate and C-reactive protein level in the simultaneous bilateral TKA patients, they failed to note a clinically significant difference in outcomes.

    Other reviews have focused on the possibility of an increased infection risk in simultaneous bilateral TKA, but have failed to note a significant increase in infections as compared with staged bilateral TKA. In fact, one such paper noted an increased infection risk in the second TKA of a staged procedure. [5]

    Cost Savings with Simultaneous Procedures

    Perhaps the most definitive benefit of simultaneous bilateral TKA is the cost savings. One study noted a cost difference of approximately $28,800, in which the difference in cost was attributed to the doubled cost of preoperative testing, blood testing, and physical therapy with staged bilateral TKA. [6]

    Despite the potential benefits of simultaneous bilateral TKA, it should be noted that many of the recent studies assessing the safety of simultaneous bilateral TKA include strict patient inclusion and exclusion criteria.

    Therefore, it is imperative to identify which patients are at particular risk when undergoing simultaneous bilateral TKA and strongly consider staged bilateral TKA, regardless of the potential economic benefit of simultaneous bilateral TKA.

    Reducing the Risk of Embolic End-organ Events

    Much of the risk-related simultaneous bilateral TKA literature beyond VTE and infection focuses on decreasing embolic end-organ events related to tourniquet use and release. It has been well documented that such embolic events can occur on release of a tourniquet within a minute of deflation; there is potentially an increased incidence with increased tourniquet time. [7,8]

    Simultaneous bilateral TKA has, therefore, been advocated only for those patients with no evidence of right ventricle vulnerability, thus excluding patients with congestive heart failure, pulmonary hypertension, or sleep apnea [9].

    As emboli are not necessarily restricted to the cardiopulmonary system, other authors have recommended screening out any patient with high susceptibility for end-organ damage when considering simultaneous bilateral TKA. [10]

    From a global health perspective, a consideration may be to simplify preoperative screening to limit simultaneous bilateral TKA to those with an American Society of Anesthesiologists (ASA) score of 1 or 2. Moreover, if a patient falls into these risk categories and is to undergo simultaneous bilateral TKA, strong consideration should be made to performing the procedure without tourniquet or at least avoiding having both tourniquets inflated simultaneously.

    The Role of Age in Bilateral TKA

    Assessment of a patient’s ability to tolerate simultaneous bilateral TKA should include an age assessment.

    While older patients have benefitted from simultaneous bilateral TKA in prior studies, they experienced postoperative complications that could potentially be more problematic to this specific population. [11] As with most other surgeries, older patients demonstrate an increased risk for urinary tract infection, delirium, and pressure ulcers following simultaneous bilateral TKA.

    Additionally, 1 study demonstrated that the risk of myocardial infarction after simultaneous bilateral TKA increased in patients in their 80s as compared to those in their 70s, with no myocardial infarctions occurring in any patient under age 70 years. [12]

    Author Information

    Daniel C. Smith, MD, is a fellow in adult reconstruction at NYU Langone Medical Center – Hospital for Joint Diseases, New York, New York. Jonathan M. Vigdorchik, MD, is the Associate Fellowship Director and an Assistant Professor of Orthopaedic Surgery, NYU Langone Medical Center – Hospital for Joint Diseases, New York, New York.


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