- Email: [email protected]
Bilateral Simultaneous vs Staged Total Knee Arthroplasty: Minimal Difference in Perioperative Risks
The Journal of Arthroplasty xxx (2019) 1e6
Contents lists available at ScienceDirect
The Journal of Arthroplasty journal homepage: www.arthroplastyjournal.org
Bilateral Simultaneous vs Staged Total Knee Arthroplasty: Minimal Difference in Perioperative Risks Ellen L. Tsay, MS *, Trevor R. Grace, MD, Thomas Vail, MD, Derek Ward, MD Department of Orthopaedic Surgery, University of California, San Francisco, San Francisco, CA
a r t i c l e i n f o
a b s t r a c t
Article history: Received 19 March 2019 Received in revised form 15 June 2019 Accepted 1 July 2019 Available online xxx
Background: With the rising utilization of total joint arthroplasty, the role of simultaneous-bilateral surgery will have an expanding impact. The purpose of this study is to examine the risks of perioperative complications with this approach in total knee arthroplasty (TKA), to inform shared decision-making. Methods: We reviewed national hospital discharge data from 2005 to 2014 to compare outcomes between simultaneous-bilateral TKAs (sim-BTKAs) and staged-bilateral TKAs (staged-BTKAs). Hierarchical logistic regression analyses were used to adjust for confounders. Outcomes analyzed included mortality, various medical complications, knee infection, and mechanical complications. Results: This study analyzed 27,301 sim-BTKAs and 45,419 staged-BTKAs. Patients who underwent simultaneous surgery had a statistically significant higher adjusted odds of mortality, cardiac events, thromboembolic events, and complications involving the urinary and digestive systems, and a lower adjusted odds of deep knee infection and hematoma. Thirteen of the 14 complications had overall incidences less than 2% and 1 outcome had an incidence of 3%. The absolute between-group risk difference for any complication was 1% or less. Conclusion: Sim-BTKAs have a statistically significant increased odds of multiple complications compared to staged-BTKAs. However, the absolute risk differences between these options are minimal and the occurrence of any complication is low. Level of Evidence: Therapeutic Level III. © 2019 Elsevier Inc. All rights reserved.
Keywords: knee arthroplasty simultaneous bilateral staged joint arthroplasty
As the population ages over the coming decades, the prevalence of knee osteoarthritis and thus the demand for surgical knee arthroplasty are expected to rise [1,2]. In fact, the number of total knee arthroplasties (TKAs) performed in the United States is projected to reach 3.48 million per year by 2030, representing a 675% increase from 2005 [2]. To meet these rising demands, the role of simultaneous-bilateral surgery will likely expand in the treatment of patients with bilateral symptomatic arthritis [1]. However, an accurate and up-to-date understanding of their risks is required if simultaneous-bilateral arthroplasties are to be considered over staged arthroplasties [3]. Prior studies have shown variable differences in perioperative risks between simultaneous-bilateral total knee arthroplasty (sim-
BTKA) and staged-bilateral total knee arthroplasty (staged-BTKA). Some studies report considerably higher mortality and cardiopulmonary risk with sim-BTKA, whereas others report reduced risks of periprosthetic joint infection and mechanical malfunction [3e6]. In the face of evolving evidence and rising demands, further assessment of these perioperative risks is warranted. The purpose of this study is to compare outcomes between simBTKA and staged-BTKA in a large, diverse patient population over a recent time frame to quantify and appropriately categorize the associated risks of these 2 surgical knee arthroplasty options. Materials and Methods Inclusion Criteria
One or more of the authors of this paper have disclosed potential or pertinent conflicts of interest, which may include receipt of payment, either direct or indirect, institutional support, or association with an entity in the biomedical field which may be perceived to have potential conflict of interest with this work. For full disclosure statements refer to https://doi.org/10.1016/j.arth.2019.07.002. * Reprint requests: Ellen L. Tsay, MS, Department of Orthopaedic Surgery, University of California, San Francisco, San Francisco, CA 94143. https://doi.org/10.1016/j.arth.2019.07.002 0883-5403/© 2019 Elsevier Inc. All rights reserved.
This study involved a retrospective analysis of nation-wide linked discharge data from all inpatient care records from community hospitals in the states of California, Florida, New York, North Carolina, Nebraska, and Utah. Patients are linked across multiple visits via a unique identifier and their diagnoses and
2
E.L. Tsay et al. / The Journal of Arthroplasty xxx (2019) 1e6
procedures tracked using the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) coding system. Records were acquired from the State Inpatient Databases, developed as part of the Healthcare Cost and Utilization Project [7]. Records were extracted for all patients who underwent at least 1 TKA between the years of 2005 and 2014 using the ICD-9 code 81.54. Patients were identified as having undergone a sim-BTKA if they received 2 primary TKA procedure codes on the same day. Patients were identified as having undergone a staged-BTKA if they received 2 primary TKA procedure codes on separate days and within 365 days of one another. Outcome Evaluation Fourteen unique outcomes were identified using the appropriate ICD-9-CM codes (Appendix A). Death was evaluated within the first 30 days, 90 days, and 1 year after surgery. Perioperative complications evaluated within the first 30 days of surgery included ischemic stroke, myocardial infarction, other cardiac complications, respiratory complications, digestive complications, urinary complications, and hematoma. Medical complications evaluated during first 60 days of surgery included deep vein thrombosis and pulmonary embolism. Orthopedic complications of deep knee infection, superficial knee infection, major mechanical malfunction, and minor mechanical malfunction were evaluated within 1 year of surgery. Deep knee infection was defined as a periprosthetic joint infection requiring revision knee arthroplasty, device or liner removal, arthrotomy, debridement, synovectomy, or other excision. Superficial knee infection was defined as a periprosthetic joint infection not requiring the aforementioned procedures. Mechanical malfunction included issues such as loosening, surface wear, dislocation, ankylosis, periprosthetic fracture, and periprosthetic osteolysis. Malfunctions requiring subsequent reoperation or revision knee arthroplasty were considered major mechanical malfunctions, while those that only required subsequent lysis of adhesions were considered minor mechanical malfunctions. Statistical Analysis First, the incidence of each outcome was calculated for the simBTKA and staged-BTKA cohorts and followed over time to determine whether any trends or changes had occurred over the study period. In addition, for the staged-BTKA cohort, we calculated separate incidence rates for patients who waited different amounts of time between the 2 operations in order to ascertain whether the timing of second surgery affects outcomes. To determine the unadjusted relative odds of developing each outcome with sim-BTKA compared to staged-BTKA, univariate logistic regression analyses were performed for each outcome. Next, to adjust for potential confounders, we built separate hierarchical multivariate logistic regression analyses with adjustment for age, sex, race, payer, morbid obesity, obesity, and Charlson Comorbidity Index (CCI) all treated as fixed effects, and hospital treated as a random effect. The CCI is a tool for predicting mortality that has been widely used and validated in various patient populations [8]. The CCI score is a weighted sum of chronic risk factors such as diabetes, hemiplegia, rheumatic disease, cerebrovascular disease, and other conditions. In this study, CCI scores were calculated from patients’ diagnosis codes and used as a proxy for their health status and comorbid conditions. In addition to an overall comparison between the sim-BTKA and staged-BTKA cohorts, stratified comparisons were also made comparing simBTKAs to (1) staged-BTKAs with 1-90 days between operations, (2) staged-BTKAs with 91-180 days between operations, and (3) staged-BTKAs with 181-365 days in between operations.
Statistical Software Analyses were performed in R 3.3.3 using the stats package glm() function for univariate analyses and lme4 package glmer() function for multivariate analyses [9,10]. Results Baseline Characteristics Between 2005 and 2014, 72,720 patients met the inclusion criteria. Out of these, 27,301 underwent sim-BTKA and 45,419 underwent staged-BTKA (Table 1). The mean age of the sim-BTKA patients was similar to that of the staged-BTKA patients, but a greater proportion of these patients were male, white, and had commercial insurance. Staged-BTKA patients had slightly higher CCI scores than sim-BTKA patients and were more likely to be obese or morbidly obese. The baseline characteristics of the study population remained similar over time, from 2005 to 2012. The mean time interval between the first-stage and second-stage surgeries was 181 days (range, 1-365 days). Complication Rates All 14 outcomes were uncommon: the risks of developing any single complication ranged from 0.1% to 3.6% within a cohort, and over 90% of patients did not experience any of the outcomes assessed. Nine complications had overall incidences of 1% or less, and 4 complications had incidences less than 2%. Deep vein thrombosis in the 60 days following surgery was the most frequent outcome (rate ¼ 3% overall; 3.6% in simultaneous; 2.8% in staged), Table 1 Baseline Demographics. Risk Factor
Age (y)a <50 50-64 65-74 >74 Male sex Race White Black Hispanic Asian Other Payerb Medicare Medicaid Commercial Other Chronic comorbidity Morbid obesity Obesity Charlson Comorbidity Index scorec 0 1-2 3-4 5þ
Simultaneous (N ¼ 27,301)
Staged (N ¼ 45,419)
No.
%
No.
%
1095 10,734 10,344 5128 11,807
4.0 39.3 37.9 18.8 43.2
1938 16,211 17,372 9898 16,980
4.3 35.7 38.2 21.8 37.4
23,394 1441 1345 496 625
85.7 5.3 4.9 1.8 2.3
36,345 2750 4246 1010 1068
80 6.1 9.3 2.2 2.4
14,752 441 11,297 811
54.0 1.6 41.4 3.0
26,359 1495 15,703 1862
58 3.3 34.6 4.1
1832 4117
6.7 15.1
6019 11,542
13.3 25.4
591 11,234 12,056 3420
2.2 41.1 44.2 12.5
619 13,875 21,462 9463
1.4 30.6 47.3 20.8
Sim-BTKA, simultaneous-bilateral total knee arthroplasty; staged-TKA, stagedbilateral total knee arthroplasty. a The mean age was 65.8 y for sim-BTKA patients and 66.6 y for staged-BTKA patients. b For patients in the staged cohort, the value at the first arthroplasty was used. c The mean Charlson Comorbidity Index score was 2.91 for sim-BTKA patients and 3.40 for staged-BTKA patients.
E.L. Tsay et al. / The Journal of Arthroplasty xxx (2019) 1e6 Table 2 Unadjusted Rates of Complications in the Study Cohorts. Complication
Death (30 d) Death (90 d) Death (1 y) Myocardial infarction (30 d) Ischemic stroke (30 d) Cardiac complications (30 d) Respiratory complications (30 d) Digestive complications (30 d) Urinary complications (30 d) Hematoma (30 d) Deep vein thrombosis (60 d) Pulmonary embolism (60 d) Deep knee infection (1 y) Superficial knee infection (1 y) Major mechanical malfunction (1 y) Minor mechanical malfunction (1 y) Complication
Death (30 d) Death (90 d) Death (1 y) Myocardial infarction (30 d) Ischemic stroke (30 d) Cardiac complications (30 d) Respiratory complications (30 d) Digestive complications (30 d) Urinary complications (30 d) Hematoma (30 d) Deep vein thrombosis (60 d) Pulmonary embolism (60 d) Deep knee infection (1 y) Superficial knee infection (1 y) Major mechanical malfunction (1 y) Minor mechanical malfunction (1 y)
Simultaneous (N ¼ 27,301)
Staged (N ¼ 45,419)a
No.
%
No.
64 83 110 156
0.2 0.3 0.4 0.6
44 63 170 125
0.1 0.1 0.4 0.3
78
0.3
73
0.2
404
1.5
567
1.2
182
0.7
300
0.7
468
1.7
454
1.0
262
1.0
407
0.9
158 982
0.6 3.6
442 1197
1.0 2.6
397
1.5
350
0.8
206
0.8
567
1.2
20
0.1
31
0.1
97
0.4
240
0.5
2
0.0
0
0
%
StageddStratified by Time Intervala (%) 1-90 d (N ¼ 9229)
91-180 d (N ¼ 15,445)
181-365 d (N ¼ 20,745)
0.1 0.2 0.4 0.2
0.1 0.1 0.4 0.2
0.1 0.1 0.4 0.3
0.1 0.9
0.1 1.2
0.2 1.4
0.4
0.7
0.8
0.9
0.9
1.1
0.6
0.8
1.1
0.8 1.9
1.0 2.5
1.0 3.0
0.4
0.7
1.0
0.9
1.4
1.3
0.1
0.1
0.1
0.6
0.5
0.5
0.0
0.0
0.0
a For the staged cohort, complication rates denote the proportion of patients who experienced at least 1 complication within the specified number of days following either the first or second stage of surgery.
while superficial knee infection and death within 30 days of surgery were among the least frequent (Table 2). Only 1 patient experienced a minor mechanical malfunction within 1 year, and therefore this outcome was excluded from further analysis. The absolute risk difference for any complication between the sim-
3
BTKA and staged-BTKA cohorts was 1% or less. The absolute risk differences were also 1% or less when comparing staged-BTKAs with different lengths of time between stages (Table 2). A longer time interval between stages corresponded to a half percent higher rate of cardiorespiratory complications, urinary complications, pulmonary embolism, and deep knee infection, and a 1% rise in deep venous thrombosis. Over the time period of the study from 2005 to 2012, all outcomes saw a small reduction in risk. The incidence of respiratory complications was reduced 1.2% for both sim-BTKAs and stagedBTKAs (from 1.2% to 0%), deep vein thrombosis was reduced 1.1% for sim-BTKAs only (from 3.7% to 2.6%), and other complications saw reductions smaller than 1%. Univariate Analysis When analyses were performed without adjusting for confounders, the sim-BTKA cohort was found to have statistically significant higher unadjusted odds of mortality within 30 and 90 days of operation, compared to the staged-BTKA cohort (Table 3). This mortality difference disappeared at 1 year. Sim-BTKA patients also had statistically significant increased unadjusted odds of cardiac events (myocardial infarction and other cardiac complications), thromboembolic events (ischemic stroke, deep vein thrombosis, pulmonary embolism), and digestive complications. On the other hand, the sim-BTKA cohort had lower odds of deep knee infection, major mechanical malfunction, and hematoma. There was no significant difference in other respiratory complications, urinary complications, or superficial knee infection. Multivariate Analysis After adjusting for potential confounders, all significant findings persisted with the addition of several new findings (Table 3 and Fig.1). Specifically, the sim-BTKA cohort continued to have increased odds of mortality within 30 days (odds ratio [OR] ¼ 3.37, 95% confidence interval [CI] ¼ 2.2-5.16) and 90 days (OR ¼ 2.93, 95% CI ¼ 2.05-4.18) compared to the entire staged-BTKA cohort, but now also had an increased odds of mortality within 1 year (OR ¼ 1.36, 95% CI ¼ 1.06-1.75). Stratified analysis revealed that this increased odds of 1-year mortality with sim-BTKAs was only significant when comparing to staged-BTKAs with 181-365 days between stages (OR ¼ 1.38, 95% CI ¼ 1.01-1.87), and no longer significant when compared to staged-BTKAs with shorter time intervals. Again, sim-BTKA patients were found to have increased odds of cardiac events such as myocardial infarction (OR ¼ 2.74, 95% CI ¼ 2.15-3.49) and other cardiac complications (OR ¼ 1.34, 95% CI ¼ 1.161.55), thromboembolic events such as ischemic stroke (OR ¼ 2.33, 95% CI ¼ 1.64-3.3), deep vein thrombosis (OR ¼ 1.36, 95% CI ¼ 1.231.5), and pulmonary embolism (OR ¼ 2.04, 95% CI ¼ 1.76-2.37), and of digestive complications (OR ¼ 1.91, 95% CI ¼ 1.65-2.2) compared to the entire staged-BTKA cohort. Additionally, the sim-BTKA cohort was found to have an increased odds of respiratory complications (OR ¼ 1.26, 95% CI ¼ 1.02-1.55) and urinary complications (OR ¼ 1.37, 95% CI ¼ 1.15-1.63). However, these 2 differences disappeared as the time interval of staged surgery increased. Specifically, sim-BTKA had a significantly higher odds of respiratory complications when compared to staged BTKAs 1-90 days apart (OR ¼ 1.9, 95% CI ¼ 1.292.8), but not when compared to staged-BTKAs 91-180 or 181-365 days apart. Similarly, sim-BTKA had a significantly higher odds of urinary complications when compared to staged-BTKAs 0-90 days apart (OR ¼ 1.91, 95% CI ¼ 1.4-2.62) and 91-180 days apart (OR ¼ 1.52, 95% CI ¼ 1.2-1.93), but not 181-365 days apart. There remained a lower odds of hematoma (OR ¼ 0.58, 95% CI ¼ 0.47-0.7), deep knee infection (OR ¼ 0.71, 95% CI ¼ 0.6-0.85), and
4
E.L. Tsay et al. / The Journal of Arthroplasty xxx (2019) 1e6
Table 3 Unadjusted and Risk-Adjusted Odds of Complications. Complication
Unadjusted Comparison Adjusted Comparison OR (95% CI)
Death (30 d) Death (90 d) Death (1 y) Myocardial infarction (30 d) Ischemic stroke (30 d) Cardiac complications (30 d) Respiratory complications (30 d) Digestive complications (30 d) Urinary complications (30 d) Hematoma (30 d) Deep vein thrombosis (60 d) Pulmonary embolism (60 d) Deep knee infection (1 y) Superficial knee infection (1 y) Major mechanical malfunction (1 y)
2.42 2.2 1.08 2.08
P Value OR (95% CI) b
(1.65-3.56) <.001 (1.58-3.05) <.001b (0.85-1.37) .55 (1.65-2.64) <.001b
3.37 2.93 1.36 2.74
(2.2-5.16) (2.05-4.18) (1.06-1.75) (2.15-3.49)
1.78 (1.29-2.45) <.001b 2.33 (1.64-3.3) 1.19 (1.04-1.35)
.009b 1.34 (1.16-1.55)
1.01 (0.84-1.21)
.92
1.26 (1.02-1.55)
P Value <.001b <.001b .015b <.001b <.001b <.001b .034b
1.73 (1.52-1.97) <.001b 1.91 (1.65-2.2)
<.001b
1.07 (0.92-1.25)
<.001b
.38
1.37 (1.15-1.63)
0.59 (0.49-0.71) <.001b 0.58 (0.47-0.7) 1.38 (1.26-1.5) <.001b 1.36 (1.23-1.5) 1.9 (1.64-2.2)
<.001b 2.04 (1.76-2.37)a <.001b
0.6 (0.51-0.71) <.001b 0.71 (0.6-0.85) 1.07 (0.61-1.88) 0.67 (0.53-0.85)
<.001b <.001b
.80 .001
b
<.001b
1.21 (0.63-2.32)
.57
0.75 (0.58-0.98)
.036b
This table shows the odds of developing each complication after simultaneous surgery, with staged surgery as the reference group. Adjusted comparisons adjusted for age, sex, race (white, black, Hispanic, Asian, other), payer (Medicare, Medicaid, Commercial, other), obesity, morbid obesity, and CCI score as fixed effects and hospital as a random effect, except for a. OR, odds ratio; CI, confidence interval. a Did not adjust for hospital center. b P < .05.
major mechanical malfunction (OR ¼ 0.75, 95% CI ¼ 0.58-0.98) for simultaneous vs staged patients overall. However, the difference in deep knee infection disappeared when comparing sim-BTKA to staged-BTKA with the shortest time interval of 1-90 days. Furthermore, the decreased odds of major mechanical malfunction with simBTKA was not significant for staged-BTKA 91-180 days apart. There remained no significant difference in superficial knee infection. Discussion Considering the rising demand for knee arthroplasties with an aging US population [1,2], simultaneous-bilateral surgeries may become more common as surgeons aim at maximizing productivity and minimizing wait times for these effective procedures. To better characterize the impact of simultaneous knee arthroplasties, the present study aimed at comparing the perioperative and postoperative risks of sim-BTKAs vs staged-BTKAs in a large, diverse patient population over a recent time frame. In doing so, we showed that sim-BTKA has higher risks of multiple adverse outcomes relative to staged-BTKA, but these outcomes were uncommon and the absolute risk differences between cohorts small. We also showed that the timing of staged surgery has a minimal impact on absolute risks but a significant impact on the relative risk comparison between simultaneous and staged surgery. While the majority of TKAs are unilateral, approximately 7% of these procedures are performed as simultaneous-bilateral arthroplasties and approximately 15% are performed as staged-bilateral arthroplasties [11]. Proponents of sim-BTKA highlight its many advantages, which include shorter overall length of stay, higher patient satisfaction, reduced cost, and speed of recovery [12e14]. However, there are multiple reports to suggest that sim-BTKAs have increased
rates of certain adverse outcomes [4,5,15e18]. The utility of simultaneous knee arthroplasties remains controversial [3]. The present study findings are consistent with those of a retrospective cohort study by Meehan et al [4], which demonstrated a decreased odds of joint infection with sim-BTKA compared to staged-BTKA. This differs from a case-control study by Pulido et al [19] which found sim-BTKA to be an independent risk factor for developing prosthetic joint infections. However, Pulido et al compared sim-BTKAs to a heterogeneous group including both staged-BTKAs and unilateral TKAs. By limiting our study cohort to patients with bilateral disease requiring 2 arthroplasties, we are able to demonstrate that simultaneous-bilateral surgery poses a reduced risk of joint infection requiring reoperation compared to staged-bilateral surgery. The present study findings also support prior findings that patients who underwent sim-BTKAs have a higher risk of cardiac complications [4,5,20], death [5,17,18], stroke [4], venous thromboembolism [5,15], urinary complications [4], and digestive complications [4] compared to their staged-BTKA counterparts, even after adjusting for confounders. Patients who underwent simultaneous surgery tended to be healthier than those who underwent staged surgery, most likely reflecting careful preoperative patient selection. The fact that these patients face increased odds of multiple complications, even after accounting for these baseline differences in health, points toward the inherent risk in undergoing this larger, more extensive surgery. On the other hand, the risks of staged surgery are likely underestimated in this study. Due to its retrospective nature, this study could only identify staged patients who had successfully completed both operations, and not those who had dropped out due to a disqualifying health event. In fact, anywhere from 10% to 14% of all staged patients may be unaccounted for, if using complication rates of completed staged-BTKAs in this study as a conservative estimate and published complication rates of unilateral TKAs as an upper estimate [4,21]. By not accounting for staged dropouts and their associated complications, the risks of staged surgery may be downplayed. Overall, all complications are rare and the absolute risk differences between the simultaneous and staged cohorts are small. The frequencies of many outcomes analyzed in this study are comparable to those reported in prior literature, with most occurring in less than 1% of patients [4,15]. These incidences may be lower in specific patient groups [16,20], indicating that careful consideration of patient characteristics is vital when selecting candidates for simultaneous surgery. This study also examined the effect of staged surgery timing on its risk profile relative to simultaneous surgery. The optimal timing of staged surgery remains an area of controversy and despite wide consensus among surgeons that surgeries should be staged at least 90 days apart to minimize mortality and overall complications, there remains significant variation in practice [3,22,23]. In this study, the timing of staged surgery had surprisingly minimal effect on complication rates. This is consistent with the findings of 2 recent studies by Chen et al and Yeh et al [22,23]. However, the timing of staged surgery did modify the comparative risk profiles of simultaneous vs staged surgery. For instance, closely staged BTKAs no longer had any benefit in 1-year mortality over simultaneous BTKAs. The odds of acquiring a prosthetic infection that required reoperation was similar between simultaneous surgery and closely spaced staged surgeries, but as the time interval between surgeries increased so did the odds of infection. This suggests that having 2 separate exposures over time poses a greater risk of infection than a single exposure or exposures over a short time frame. The risks and benefits of simultaneous and staged surgery should be weighed in each individual scenario and are influenced by patient factors as well as the timing of staged surgery.
E.L. Tsay et al. / The Journal of Arthroplasty xxx (2019) 1e6
5
Fig. 1. Risk-adjusted odds ratios and confidence intervals (#) within 60 days; (o) within 90 days; and (*) within 365 days. All other complications were measured within 30 days. The adjusted odds of complications occurring after sim-BTKA compared to staged-BTKA, with staged-BTKAs stratified by the number of days that passed between stages. Bars represent the 95% confidence intervals. Did not adjust for hospital center in models for superficial knee infection (for 1- to 90-day and 91- to 180-day intervals), ischemic stroke (for 1- to 90-day and 91- to 180-day intervals), and pulmonary embolism (for all staged-BTKAs). Sim-BTKA, simultaneous-bilateral total knee arthroplasty; staged-TKA, staged-bilateral total knee arthroplasty.
Ultimately, these 2 surgical options may have minimal differences in perioperative risks. The statistically significant differences and small absolute risk differences of these rare perioperative complications should be thoroughly discussed with patients, with the knowledge that sim-BTKAs offer many advantages [12e14]. The strengths of this study are its inclusion of inpatient data from multiple states over a recent time frame, allowing results to be more broadly generalizable to the current practice. Although surgical care has undergone multiple changes in the 9 years over which this study was conducted, outcomes remained stable with only a minimal downtrend in complication rates, and thus the study findings are relevant to modern-day practice. To our knowledge, this is the largest study to date comparing sim-BTKA and staged-BTKA with over 60,000 patients. Limitations of the present study are its retrospective nature, which as mentioned precludes intention-to-treat analyses due to difficulties in identifying patients who were initially slated for staged surgery but did not go on to complete the second stage. In addition, this study was limited to variables included in the Healthcare Cost and Utilization Project database. Thus, it did not account for unmeasured variables such as specific surgeon technique, prosthesis type, the mode and duration of deep venous thrombosis prophylaxis, or CCI score. CCI score was calculated indirectly from patient comorbidities recorded through ICD-9 coding data. Furthermore, the ICD-9 coding system does not record laterality and thus we used the time of occurrence in order to associate complications such as infection and mechanical malfunction with a particular stage of surgery. Large, randomized, prospective studies are needed in order to further define the differences in outcomes between simultaneous and staged
surgery and to best prepare orthopedic surgeons and providers for the impending surge in demand for TKAs. Conclusions Despite a higher statistical odds of experiencing many adverse outcomes for patients who undergo sim-BTKA vs staged-BTKA, these outcomes are all uncommon and the absolute differences in perioperative risks between these 2 surgical options are small. These minimal differences in absolute risk and their interplay with patient-specific as well as surgery-specific factors should be taken into consideration when discussing the advantages and disadvantages of both options for bilateral knee arthroplasty, timing of staged surgery, relative risks of specific complications, and informing shared decision-making. Acknowledgments We thank Matthew Callahan for his assistance with the database, and we thank Karla Lindquist for her guidance with statistical analyses. References [1] Kurtz S, Ong K, Lau E, Mowat F, Halpern M. Projections of primary and revision hip and knee arthroplasty in the United States from 2005 to 2030. J Bone Joint Surg Am 2007;89:780. https://doi.org/10.2106/JBJS.F.00222. [2] Cross M, Smith E, Hoy D, Nolte S, Ackerman I, Fransen M, et al. The global burden of hip and knee osteoarthritis: estimates from the global burden of disease 2010 study. Ann Rheum Dis 2014;73:1323e30. https://doi.org/ 10.1136/annrheumdis-2013-204763.
6
E.L. Tsay et al. / The Journal of Arthroplasty xxx (2019) 1e6
[3] Memtsoudis SG, Hargett M, Russell LA, Parvizi J, Cats-Baril WL, Stundner O, et al. Consensus statement from the consensus conference on bilateral total knee arthroplasty group. Clin Orthop Relat Res 2013;471:2649e57. https:// doi.org/10.1007/s11999-013-2976-9. [4] Meehan JP, Danielsen B, Tancredi DJ, Kim S, Jamali AA, White RH. A population-based comparison of the incidence of adverse outcomes after simultaneous-bilateral and staged-bilateral total knee arthroplasty. J Bone Joint Surg Am 2011;93:2203e13. https://doi.org/10.2106/JBJS.J.01350. [5] Restrepo C, Parvizi J, Dietrich T, Einhorn TA. Safety of simultaneous bilateral total knee arthroplasty. A meta-analysis. J Bone Joint Surg Am 2007;89: 1220e6. https://doi.org/10.2106/JBJS.F.01353. [6] Fu D, Li G, Chen K, Zeng H, Zhang X, Cai Z. Comparison of clinical outcome between simultaneous-bilateral and staged-bilateral total knee arthroplasty: a systematic review of retrospective studies. J Arthroplasty 2013;28:1141e7. https://doi.org/10.1016/j.arth.2012.09.023. [7] HCUP Databases. Healthcare cost and utilization project (HCUP). agency for healthcare research and quality, rockville, MD. www.hcup-us.ahrq.gov/ sidoverview.jsp. Updated April, 2017. [accessed 19.04.19]. [8] Charlson ME, Pompei P, Ales KL, MacKenzie CR. A new method of classifying prognostic comorbidity in longitudinal studies: development and validation. J Chronic Dis 1987;40:373e83. [9] Bates D, Martin M, Bolker B, Walker S. Fitting linear mixed-effects models using lme4. J Stat Softw 2015;67:1. https://doi.org/10.18637/jss.v067.i01. [10] R The R Project Stat Comput n.d. https://www.r-project.org/. [Accessed 15 December 2017]. [11] Levit K, Wier L, Stranges E, Ryan K, Elixhauser A. HCUP facts and figures: Statistics on hospital-based care in the united states. http://www.hcup-us. ahrq.gov/reports.jsp; 2007. Updated 2009. [accessed 15.12.17]. [12] March LM, Cross M, Tribe KL, Lapsley HM, Courtenay BG, Cross MJ, et al. Two knees or not two knees? Patient costs and outcomes following bilateral and unilateral total knee joint replacement surgery for OA. Osteoarthr Cartil 2004;12:400e8. https://doi.org/10.1016/j.joca.2004.02.002. [13] Ritter MA, Harty LD. Debate: simultaneous bilateral knee replacements: the outcomes justify its use. Clin Orthop Relat Res 2004:84e6.
[14] Hadley S, Day M, Schwarzkopf R, Smith A, Slover J, Zuckerman J. Is simultaneous bilateral total knee arthroplasty (BTKA) as safe as staged BTKA? Am J Orthop 2017;46:E224e9. [15] Barrett J, Baron JA, Losina E, Wright J, Mahomed NN, Katz JN. Bilateral total knee replacement: staging and pulmonary embolism. J Bone Joint Surg Am 2006;88:2146e51. https://doi.org/10.2106/JBJS.E.01323. [16] Yoon H-S, Han C-D, Yang I-H. Comparison of simultaneous bilateral and staged bilateral total knee arthroplasty in terms of perioperative complications. J Arthroplasty 2010;25:179e85. https://doi.org/10.1016/j.arth.2008.11.103. [17] Hussain N, Chien T, Hussain F, Bookwala A, Simunovic N, Shetty V, et al. Simultaneous versus staged bilateral total knee arthroplasty: a meta-analysis evaluating mortality, peri-operative complications and infection rates. HSS J 2013;9:50e9. https://doi.org/10.1007/s11420-012-9315-7. ttir A, Lidgren L, Robertsson O. Higher early mortality with simul[18] Stef ansdo taneous rather than staged bilateral TKAs: results from the Swedish Knee Arthroplasty Register. Clin Orthop Relat Res 2008;466:3066e70. https:// doi.org/10.1007/s11999-008-0404-3. [19] Pulido L, Ghanem E, Joshi A, Purtill JJ, Parvizi J. Periprosthetic joint infection: the incidence, timing, and predisposing factors. Clin Orthop Relat Res 2008;466:1710e5. https://doi.org/10.1007/s11999-008-0209-4. [20] Peskun C, Mayne I, Malempati H, Kosashvili Y, Gross A, Backstein D. Cardiovascular disease predicts complications following bilateral total knee arthroplasty under a single anesthetic. Knee 2012;19:580e4. https://doi.org/10.1016/ j.knee.2011.09.010. [21] Bohm ER, Molodianovitsh K, Dragan A, Zhu N, Webster G, Masri B, et al. Outcomes of unilateral and bilateral total knee arthroplasty in 238,373 patients. Acta Orthop 2016;87:24e30. https://doi.org/10.1080/17453674.2016.1181817. [22] Chen A, Rasouli M, Vegari D, Huang R, Maltenfort M, Parvizi J. Staged bilateral total knee arthroplasty: time of the second side. J Knee Surg 2014;28:311e4. https://doi.org/10.1055/s-0034-1384215. [23] Yeh J, Chen J, Lee W, Chong H, Pang H, Tay D, et al. Identifying an ideal time frame for staged bilateral total knee arthroplasty to maximize functional outcome. J Knee Surg 2017;30:682e6. https://doi.org/10.1055/s0036-1597273.
E.L. Tsay et al. / The Journal of Arthroplasty xxx (2019) 1e6
6.e1
Appendix
Appendix A ICD-9 Codes for Complications. Complication
ICD-9 Codes
Death (30 d, 90 d, 1 y) Myocardial infarction (30 d) Ischemic stroke (30 d) Cardiac complications (30 d) Respiratory complications (30 d) Digestive complications (30 d) Urinary complications (30 d) Hematoma (30 d) Deep vein thrombosis (60 d)
Coded from discharge disposition ‘410.01’, ‘410.11’, ‘410.21’, ‘410.31’, ‘410.41’, ‘410.51’, ‘410.61’, ‘410.71’, ‘410.81’, ‘410.91’ ‘997.02’, ‘433.01’, ‘433.11’, ‘433.21’, ‘433.31’, ‘433.81’, ‘433.91’, ‘434.01’, ‘434.11’, ‘434.91’ ‘997.1’ ‘997.3’ ‘997.4’, ‘560.1’ ‘997.5’ ‘998.12’, ‘719.16’ ‘415.11’, ‘415.19’, ‘451.81’, ‘451.83’, ‘451.89’, ‘453.40’, ‘453.41’, ‘453.42’, ‘453.8’, ‘453.9’ ‘444.22’, ‘444.81’, ‘996.77’ ‘415.11’, ‘415.19’ Any of (‘996.66’, ‘996.67’, ‘998.59’) AND any of (‘00.80’, ‘00.81’, ‘00.82’, ‘00.83’, ‘00.84’, ‘80.06’, ‘80.16’, ‘80.76’, ‘80.86’, ‘80.96’, ‘81.55’, ‘86.05’, ‘86.22’) Any of (‘996.66’, ‘996.67’, ‘998.59’) WITHOUT any of (‘00.80’, ‘00.81’, ‘00.82’, ‘00.83’, ‘00.84’, ‘80.06’, ‘80.16’, ‘80.76’, ‘80.86’, ‘80.96’, ‘81.55’, ‘86.05’, ‘86.22’) Any of (‘718.36’, ‘718.56’, ‘996.40’, ‘996.41’, ‘996.42’, ‘996.43’, ‘996.44’, ‘996.45’, ‘996.46’, ‘996.47’, ‘996.49’, ‘996.77’, ‘996.78’) AND any of (‘77.86’, ‘78.55’, ‘78.67’, ‘79.06’,‘80.46’, ‘81.55’) Any of (‘718.36’, ‘718.56’, ‘996.40’, ‘996.41’, ‘996.42’, ‘996.43’, ‘996.44’, ‘996.45’, ‘996.46’, ‘996.47’, ‘996.49’, ‘996.77’, ‘996.78’) AND any of (‘83.91’)
Pulmonary embolism (60 d) Deep knee infection (1 y) Superficial knee infection (1 y) Major mechanical malfunction (1 y)
Minor mechanical malfunction (1 y)
ICD, International Classification of Diseases, Ninth Revision.
Contents lists available at ScienceDirect
The Journal of Arthroplasty journal homepage: www.arthroplastyjournal.org
Bilateral Simultaneous vs Staged Total Knee Arthroplasty: Minimal Difference in Perioperative Risks Ellen L. Tsay, MS *, Trevor R. Grace, MD, Thomas Vail, MD, Derek Ward, MD Department of Orthopaedic Surgery, University of California, San Francisco, San Francisco, CA
a r t i c l e i n f o
a b s t r a c t
Article history: Received 19 March 2019 Received in revised form 15 June 2019 Accepted 1 July 2019 Available online xxx
Background: With the rising utilization of total joint arthroplasty, the role of simultaneous-bilateral surgery will have an expanding impact. The purpose of this study is to examine the risks of perioperative complications with this approach in total knee arthroplasty (TKA), to inform shared decision-making. Methods: We reviewed national hospital discharge data from 2005 to 2014 to compare outcomes between simultaneous-bilateral TKAs (sim-BTKAs) and staged-bilateral TKAs (staged-BTKAs). Hierarchical logistic regression analyses were used to adjust for confounders. Outcomes analyzed included mortality, various medical complications, knee infection, and mechanical complications. Results: This study analyzed 27,301 sim-BTKAs and 45,419 staged-BTKAs. Patients who underwent simultaneous surgery had a statistically significant higher adjusted odds of mortality, cardiac events, thromboembolic events, and complications involving the urinary and digestive systems, and a lower adjusted odds of deep knee infection and hematoma. Thirteen of the 14 complications had overall incidences less than 2% and 1 outcome had an incidence of 3%. The absolute between-group risk difference for any complication was 1% or less. Conclusion: Sim-BTKAs have a statistically significant increased odds of multiple complications compared to staged-BTKAs. However, the absolute risk differences between these options are minimal and the occurrence of any complication is low. Level of Evidence: Therapeutic Level III. © 2019 Elsevier Inc. All rights reserved.
Keywords: knee arthroplasty simultaneous bilateral staged joint arthroplasty
As the population ages over the coming decades, the prevalence of knee osteoarthritis and thus the demand for surgical knee arthroplasty are expected to rise [1,2]. In fact, the number of total knee arthroplasties (TKAs) performed in the United States is projected to reach 3.48 million per year by 2030, representing a 675% increase from 2005 [2]. To meet these rising demands, the role of simultaneous-bilateral surgery will likely expand in the treatment of patients with bilateral symptomatic arthritis [1]. However, an accurate and up-to-date understanding of their risks is required if simultaneous-bilateral arthroplasties are to be considered over staged arthroplasties [3]. Prior studies have shown variable differences in perioperative risks between simultaneous-bilateral total knee arthroplasty (sim-
BTKA) and staged-bilateral total knee arthroplasty (staged-BTKA). Some studies report considerably higher mortality and cardiopulmonary risk with sim-BTKA, whereas others report reduced risks of periprosthetic joint infection and mechanical malfunction [3e6]. In the face of evolving evidence and rising demands, further assessment of these perioperative risks is warranted. The purpose of this study is to compare outcomes between simBTKA and staged-BTKA in a large, diverse patient population over a recent time frame to quantify and appropriately categorize the associated risks of these 2 surgical knee arthroplasty options. Materials and Methods Inclusion Criteria
One or more of the authors of this paper have disclosed potential or pertinent conflicts of interest, which may include receipt of payment, either direct or indirect, institutional support, or association with an entity in the biomedical field which may be perceived to have potential conflict of interest with this work. For full disclosure statements refer to https://doi.org/10.1016/j.arth.2019.07.002. * Reprint requests: Ellen L. Tsay, MS, Department of Orthopaedic Surgery, University of California, San Francisco, San Francisco, CA 94143. https://doi.org/10.1016/j.arth.2019.07.002 0883-5403/© 2019 Elsevier Inc. All rights reserved.
This study involved a retrospective analysis of nation-wide linked discharge data from all inpatient care records from community hospitals in the states of California, Florida, New York, North Carolina, Nebraska, and Utah. Patients are linked across multiple visits via a unique identifier and their diagnoses and
2
E.L. Tsay et al. / The Journal of Arthroplasty xxx (2019) 1e6
procedures tracked using the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) coding system. Records were acquired from the State Inpatient Databases, developed as part of the Healthcare Cost and Utilization Project [7]. Records were extracted for all patients who underwent at least 1 TKA between the years of 2005 and 2014 using the ICD-9 code 81.54. Patients were identified as having undergone a sim-BTKA if they received 2 primary TKA procedure codes on the same day. Patients were identified as having undergone a staged-BTKA if they received 2 primary TKA procedure codes on separate days and within 365 days of one another. Outcome Evaluation Fourteen unique outcomes were identified using the appropriate ICD-9-CM codes (Appendix A). Death was evaluated within the first 30 days, 90 days, and 1 year after surgery. Perioperative complications evaluated within the first 30 days of surgery included ischemic stroke, myocardial infarction, other cardiac complications, respiratory complications, digestive complications, urinary complications, and hematoma. Medical complications evaluated during first 60 days of surgery included deep vein thrombosis and pulmonary embolism. Orthopedic complications of deep knee infection, superficial knee infection, major mechanical malfunction, and minor mechanical malfunction were evaluated within 1 year of surgery. Deep knee infection was defined as a periprosthetic joint infection requiring revision knee arthroplasty, device or liner removal, arthrotomy, debridement, synovectomy, or other excision. Superficial knee infection was defined as a periprosthetic joint infection not requiring the aforementioned procedures. Mechanical malfunction included issues such as loosening, surface wear, dislocation, ankylosis, periprosthetic fracture, and periprosthetic osteolysis. Malfunctions requiring subsequent reoperation or revision knee arthroplasty were considered major mechanical malfunctions, while those that only required subsequent lysis of adhesions were considered minor mechanical malfunctions. Statistical Analysis First, the incidence of each outcome was calculated for the simBTKA and staged-BTKA cohorts and followed over time to determine whether any trends or changes had occurred over the study period. In addition, for the staged-BTKA cohort, we calculated separate incidence rates for patients who waited different amounts of time between the 2 operations in order to ascertain whether the timing of second surgery affects outcomes. To determine the unadjusted relative odds of developing each outcome with sim-BTKA compared to staged-BTKA, univariate logistic regression analyses were performed for each outcome. Next, to adjust for potential confounders, we built separate hierarchical multivariate logistic regression analyses with adjustment for age, sex, race, payer, morbid obesity, obesity, and Charlson Comorbidity Index (CCI) all treated as fixed effects, and hospital treated as a random effect. The CCI is a tool for predicting mortality that has been widely used and validated in various patient populations [8]. The CCI score is a weighted sum of chronic risk factors such as diabetes, hemiplegia, rheumatic disease, cerebrovascular disease, and other conditions. In this study, CCI scores were calculated from patients’ diagnosis codes and used as a proxy for their health status and comorbid conditions. In addition to an overall comparison between the sim-BTKA and staged-BTKA cohorts, stratified comparisons were also made comparing simBTKAs to (1) staged-BTKAs with 1-90 days between operations, (2) staged-BTKAs with 91-180 days between operations, and (3) staged-BTKAs with 181-365 days in between operations.
Statistical Software Analyses were performed in R 3.3.3 using the stats package glm() function for univariate analyses and lme4 package glmer() function for multivariate analyses [9,10]. Results Baseline Characteristics Between 2005 and 2014, 72,720 patients met the inclusion criteria. Out of these, 27,301 underwent sim-BTKA and 45,419 underwent staged-BTKA (Table 1). The mean age of the sim-BTKA patients was similar to that of the staged-BTKA patients, but a greater proportion of these patients were male, white, and had commercial insurance. Staged-BTKA patients had slightly higher CCI scores than sim-BTKA patients and were more likely to be obese or morbidly obese. The baseline characteristics of the study population remained similar over time, from 2005 to 2012. The mean time interval between the first-stage and second-stage surgeries was 181 days (range, 1-365 days). Complication Rates All 14 outcomes were uncommon: the risks of developing any single complication ranged from 0.1% to 3.6% within a cohort, and over 90% of patients did not experience any of the outcomes assessed. Nine complications had overall incidences of 1% or less, and 4 complications had incidences less than 2%. Deep vein thrombosis in the 60 days following surgery was the most frequent outcome (rate ¼ 3% overall; 3.6% in simultaneous; 2.8% in staged), Table 1 Baseline Demographics. Risk Factor
Age (y)a <50 50-64 65-74 >74 Male sex Race White Black Hispanic Asian Other Payerb Medicare Medicaid Commercial Other Chronic comorbidity Morbid obesity Obesity Charlson Comorbidity Index scorec 0 1-2 3-4 5þ
Simultaneous (N ¼ 27,301)
Staged (N ¼ 45,419)
No.
%
No.
%
1095 10,734 10,344 5128 11,807
4.0 39.3 37.9 18.8 43.2
1938 16,211 17,372 9898 16,980
4.3 35.7 38.2 21.8 37.4
23,394 1441 1345 496 625
85.7 5.3 4.9 1.8 2.3
36,345 2750 4246 1010 1068
80 6.1 9.3 2.2 2.4
14,752 441 11,297 811
54.0 1.6 41.4 3.0
26,359 1495 15,703 1862
58 3.3 34.6 4.1
1832 4117
6.7 15.1
6019 11,542
13.3 25.4
591 11,234 12,056 3420
2.2 41.1 44.2 12.5
619 13,875 21,462 9463
1.4 30.6 47.3 20.8
Sim-BTKA, simultaneous-bilateral total knee arthroplasty; staged-TKA, stagedbilateral total knee arthroplasty. a The mean age was 65.8 y for sim-BTKA patients and 66.6 y for staged-BTKA patients. b For patients in the staged cohort, the value at the first arthroplasty was used. c The mean Charlson Comorbidity Index score was 2.91 for sim-BTKA patients and 3.40 for staged-BTKA patients.
E.L. Tsay et al. / The Journal of Arthroplasty xxx (2019) 1e6 Table 2 Unadjusted Rates of Complications in the Study Cohorts. Complication
Death (30 d) Death (90 d) Death (1 y) Myocardial infarction (30 d) Ischemic stroke (30 d) Cardiac complications (30 d) Respiratory complications (30 d) Digestive complications (30 d) Urinary complications (30 d) Hematoma (30 d) Deep vein thrombosis (60 d) Pulmonary embolism (60 d) Deep knee infection (1 y) Superficial knee infection (1 y) Major mechanical malfunction (1 y) Minor mechanical malfunction (1 y) Complication
Death (30 d) Death (90 d) Death (1 y) Myocardial infarction (30 d) Ischemic stroke (30 d) Cardiac complications (30 d) Respiratory complications (30 d) Digestive complications (30 d) Urinary complications (30 d) Hematoma (30 d) Deep vein thrombosis (60 d) Pulmonary embolism (60 d) Deep knee infection (1 y) Superficial knee infection (1 y) Major mechanical malfunction (1 y) Minor mechanical malfunction (1 y)
Simultaneous (N ¼ 27,301)
Staged (N ¼ 45,419)a
No.
%
No.
64 83 110 156
0.2 0.3 0.4 0.6
44 63 170 125
0.1 0.1 0.4 0.3
78
0.3
73
0.2
404
1.5
567
1.2
182
0.7
300
0.7
468
1.7
454
1.0
262
1.0
407
0.9
158 982
0.6 3.6
442 1197
1.0 2.6
397
1.5
350
0.8
206
0.8
567
1.2
20
0.1
31
0.1
97
0.4
240
0.5
2
0.0
0
0
%
StageddStratified by Time Intervala (%) 1-90 d (N ¼ 9229)
91-180 d (N ¼ 15,445)
181-365 d (N ¼ 20,745)
0.1 0.2 0.4 0.2
0.1 0.1 0.4 0.2
0.1 0.1 0.4 0.3
0.1 0.9
0.1 1.2
0.2 1.4
0.4
0.7
0.8
0.9
0.9
1.1
0.6
0.8
1.1
0.8 1.9
1.0 2.5
1.0 3.0
0.4
0.7
1.0
0.9
1.4
1.3
0.1
0.1
0.1
0.6
0.5
0.5
0.0
0.0
0.0
a For the staged cohort, complication rates denote the proportion of patients who experienced at least 1 complication within the specified number of days following either the first or second stage of surgery.
while superficial knee infection and death within 30 days of surgery were among the least frequent (Table 2). Only 1 patient experienced a minor mechanical malfunction within 1 year, and therefore this outcome was excluded from further analysis. The absolute risk difference for any complication between the sim-
3
BTKA and staged-BTKA cohorts was 1% or less. The absolute risk differences were also 1% or less when comparing staged-BTKAs with different lengths of time between stages (Table 2). A longer time interval between stages corresponded to a half percent higher rate of cardiorespiratory complications, urinary complications, pulmonary embolism, and deep knee infection, and a 1% rise in deep venous thrombosis. Over the time period of the study from 2005 to 2012, all outcomes saw a small reduction in risk. The incidence of respiratory complications was reduced 1.2% for both sim-BTKAs and stagedBTKAs (from 1.2% to 0%), deep vein thrombosis was reduced 1.1% for sim-BTKAs only (from 3.7% to 2.6%), and other complications saw reductions smaller than 1%. Univariate Analysis When analyses were performed without adjusting for confounders, the sim-BTKA cohort was found to have statistically significant higher unadjusted odds of mortality within 30 and 90 days of operation, compared to the staged-BTKA cohort (Table 3). This mortality difference disappeared at 1 year. Sim-BTKA patients also had statistically significant increased unadjusted odds of cardiac events (myocardial infarction and other cardiac complications), thromboembolic events (ischemic stroke, deep vein thrombosis, pulmonary embolism), and digestive complications. On the other hand, the sim-BTKA cohort had lower odds of deep knee infection, major mechanical malfunction, and hematoma. There was no significant difference in other respiratory complications, urinary complications, or superficial knee infection. Multivariate Analysis After adjusting for potential confounders, all significant findings persisted with the addition of several new findings (Table 3 and Fig.1). Specifically, the sim-BTKA cohort continued to have increased odds of mortality within 30 days (odds ratio [OR] ¼ 3.37, 95% confidence interval [CI] ¼ 2.2-5.16) and 90 days (OR ¼ 2.93, 95% CI ¼ 2.05-4.18) compared to the entire staged-BTKA cohort, but now also had an increased odds of mortality within 1 year (OR ¼ 1.36, 95% CI ¼ 1.06-1.75). Stratified analysis revealed that this increased odds of 1-year mortality with sim-BTKAs was only significant when comparing to staged-BTKAs with 181-365 days between stages (OR ¼ 1.38, 95% CI ¼ 1.01-1.87), and no longer significant when compared to staged-BTKAs with shorter time intervals. Again, sim-BTKA patients were found to have increased odds of cardiac events such as myocardial infarction (OR ¼ 2.74, 95% CI ¼ 2.15-3.49) and other cardiac complications (OR ¼ 1.34, 95% CI ¼ 1.161.55), thromboembolic events such as ischemic stroke (OR ¼ 2.33, 95% CI ¼ 1.64-3.3), deep vein thrombosis (OR ¼ 1.36, 95% CI ¼ 1.231.5), and pulmonary embolism (OR ¼ 2.04, 95% CI ¼ 1.76-2.37), and of digestive complications (OR ¼ 1.91, 95% CI ¼ 1.65-2.2) compared to the entire staged-BTKA cohort. Additionally, the sim-BTKA cohort was found to have an increased odds of respiratory complications (OR ¼ 1.26, 95% CI ¼ 1.02-1.55) and urinary complications (OR ¼ 1.37, 95% CI ¼ 1.15-1.63). However, these 2 differences disappeared as the time interval of staged surgery increased. Specifically, sim-BTKA had a significantly higher odds of respiratory complications when compared to staged BTKAs 1-90 days apart (OR ¼ 1.9, 95% CI ¼ 1.292.8), but not when compared to staged-BTKAs 91-180 or 181-365 days apart. Similarly, sim-BTKA had a significantly higher odds of urinary complications when compared to staged-BTKAs 0-90 days apart (OR ¼ 1.91, 95% CI ¼ 1.4-2.62) and 91-180 days apart (OR ¼ 1.52, 95% CI ¼ 1.2-1.93), but not 181-365 days apart. There remained a lower odds of hematoma (OR ¼ 0.58, 95% CI ¼ 0.47-0.7), deep knee infection (OR ¼ 0.71, 95% CI ¼ 0.6-0.85), and
4
E.L. Tsay et al. / The Journal of Arthroplasty xxx (2019) 1e6
Table 3 Unadjusted and Risk-Adjusted Odds of Complications. Complication
Unadjusted Comparison Adjusted Comparison OR (95% CI)
Death (30 d) Death (90 d) Death (1 y) Myocardial infarction (30 d) Ischemic stroke (30 d) Cardiac complications (30 d) Respiratory complications (30 d) Digestive complications (30 d) Urinary complications (30 d) Hematoma (30 d) Deep vein thrombosis (60 d) Pulmonary embolism (60 d) Deep knee infection (1 y) Superficial knee infection (1 y) Major mechanical malfunction (1 y)
2.42 2.2 1.08 2.08
P Value OR (95% CI) b
(1.65-3.56) <.001 (1.58-3.05) <.001b (0.85-1.37) .55 (1.65-2.64) <.001b
3.37 2.93 1.36 2.74
(2.2-5.16) (2.05-4.18) (1.06-1.75) (2.15-3.49)
1.78 (1.29-2.45) <.001b 2.33 (1.64-3.3) 1.19 (1.04-1.35)
.009b 1.34 (1.16-1.55)
1.01 (0.84-1.21)
.92
1.26 (1.02-1.55)
P Value <.001b <.001b .015b <.001b <.001b <.001b .034b
1.73 (1.52-1.97) <.001b 1.91 (1.65-2.2)
<.001b
1.07 (0.92-1.25)
<.001b
.38
1.37 (1.15-1.63)
0.59 (0.49-0.71) <.001b 0.58 (0.47-0.7) 1.38 (1.26-1.5) <.001b 1.36 (1.23-1.5) 1.9 (1.64-2.2)
<.001b 2.04 (1.76-2.37)a <.001b
0.6 (0.51-0.71) <.001b 0.71 (0.6-0.85) 1.07 (0.61-1.88) 0.67 (0.53-0.85)
<.001b <.001b
.80 .001
b
<.001b
1.21 (0.63-2.32)
.57
0.75 (0.58-0.98)
.036b
This table shows the odds of developing each complication after simultaneous surgery, with staged surgery as the reference group. Adjusted comparisons adjusted for age, sex, race (white, black, Hispanic, Asian, other), payer (Medicare, Medicaid, Commercial, other), obesity, morbid obesity, and CCI score as fixed effects and hospital as a random effect, except for a. OR, odds ratio; CI, confidence interval. a Did not adjust for hospital center. b P < .05.
major mechanical malfunction (OR ¼ 0.75, 95% CI ¼ 0.58-0.98) for simultaneous vs staged patients overall. However, the difference in deep knee infection disappeared when comparing sim-BTKA to staged-BTKA with the shortest time interval of 1-90 days. Furthermore, the decreased odds of major mechanical malfunction with simBTKA was not significant for staged-BTKA 91-180 days apart. There remained no significant difference in superficial knee infection. Discussion Considering the rising demand for knee arthroplasties with an aging US population [1,2], simultaneous-bilateral surgeries may become more common as surgeons aim at maximizing productivity and minimizing wait times for these effective procedures. To better characterize the impact of simultaneous knee arthroplasties, the present study aimed at comparing the perioperative and postoperative risks of sim-BTKAs vs staged-BTKAs in a large, diverse patient population over a recent time frame. In doing so, we showed that sim-BTKA has higher risks of multiple adverse outcomes relative to staged-BTKA, but these outcomes were uncommon and the absolute risk differences between cohorts small. We also showed that the timing of staged surgery has a minimal impact on absolute risks but a significant impact on the relative risk comparison between simultaneous and staged surgery. While the majority of TKAs are unilateral, approximately 7% of these procedures are performed as simultaneous-bilateral arthroplasties and approximately 15% are performed as staged-bilateral arthroplasties [11]. Proponents of sim-BTKA highlight its many advantages, which include shorter overall length of stay, higher patient satisfaction, reduced cost, and speed of recovery [12e14]. However, there are multiple reports to suggest that sim-BTKAs have increased
rates of certain adverse outcomes [4,5,15e18]. The utility of simultaneous knee arthroplasties remains controversial [3]. The present study findings are consistent with those of a retrospective cohort study by Meehan et al [4], which demonstrated a decreased odds of joint infection with sim-BTKA compared to staged-BTKA. This differs from a case-control study by Pulido et al [19] which found sim-BTKA to be an independent risk factor for developing prosthetic joint infections. However, Pulido et al compared sim-BTKAs to a heterogeneous group including both staged-BTKAs and unilateral TKAs. By limiting our study cohort to patients with bilateral disease requiring 2 arthroplasties, we are able to demonstrate that simultaneous-bilateral surgery poses a reduced risk of joint infection requiring reoperation compared to staged-bilateral surgery. The present study findings also support prior findings that patients who underwent sim-BTKAs have a higher risk of cardiac complications [4,5,20], death [5,17,18], stroke [4], venous thromboembolism [5,15], urinary complications [4], and digestive complications [4] compared to their staged-BTKA counterparts, even after adjusting for confounders. Patients who underwent simultaneous surgery tended to be healthier than those who underwent staged surgery, most likely reflecting careful preoperative patient selection. The fact that these patients face increased odds of multiple complications, even after accounting for these baseline differences in health, points toward the inherent risk in undergoing this larger, more extensive surgery. On the other hand, the risks of staged surgery are likely underestimated in this study. Due to its retrospective nature, this study could only identify staged patients who had successfully completed both operations, and not those who had dropped out due to a disqualifying health event. In fact, anywhere from 10% to 14% of all staged patients may be unaccounted for, if using complication rates of completed staged-BTKAs in this study as a conservative estimate and published complication rates of unilateral TKAs as an upper estimate [4,21]. By not accounting for staged dropouts and their associated complications, the risks of staged surgery may be downplayed. Overall, all complications are rare and the absolute risk differences between the simultaneous and staged cohorts are small. The frequencies of many outcomes analyzed in this study are comparable to those reported in prior literature, with most occurring in less than 1% of patients [4,15]. These incidences may be lower in specific patient groups [16,20], indicating that careful consideration of patient characteristics is vital when selecting candidates for simultaneous surgery. This study also examined the effect of staged surgery timing on its risk profile relative to simultaneous surgery. The optimal timing of staged surgery remains an area of controversy and despite wide consensus among surgeons that surgeries should be staged at least 90 days apart to minimize mortality and overall complications, there remains significant variation in practice [3,22,23]. In this study, the timing of staged surgery had surprisingly minimal effect on complication rates. This is consistent with the findings of 2 recent studies by Chen et al and Yeh et al [22,23]. However, the timing of staged surgery did modify the comparative risk profiles of simultaneous vs staged surgery. For instance, closely staged BTKAs no longer had any benefit in 1-year mortality over simultaneous BTKAs. The odds of acquiring a prosthetic infection that required reoperation was similar between simultaneous surgery and closely spaced staged surgeries, but as the time interval between surgeries increased so did the odds of infection. This suggests that having 2 separate exposures over time poses a greater risk of infection than a single exposure or exposures over a short time frame. The risks and benefits of simultaneous and staged surgery should be weighed in each individual scenario and are influenced by patient factors as well as the timing of staged surgery.
E.L. Tsay et al. / The Journal of Arthroplasty xxx (2019) 1e6
5
Fig. 1. Risk-adjusted odds ratios and confidence intervals (#) within 60 days; (o) within 90 days; and (*) within 365 days. All other complications were measured within 30 days. The adjusted odds of complications occurring after sim-BTKA compared to staged-BTKA, with staged-BTKAs stratified by the number of days that passed between stages. Bars represent the 95% confidence intervals. Did not adjust for hospital center in models for superficial knee infection (for 1- to 90-day and 91- to 180-day intervals), ischemic stroke (for 1- to 90-day and 91- to 180-day intervals), and pulmonary embolism (for all staged-BTKAs). Sim-BTKA, simultaneous-bilateral total knee arthroplasty; staged-TKA, staged-bilateral total knee arthroplasty.
Ultimately, these 2 surgical options may have minimal differences in perioperative risks. The statistically significant differences and small absolute risk differences of these rare perioperative complications should be thoroughly discussed with patients, with the knowledge that sim-BTKAs offer many advantages [12e14]. The strengths of this study are its inclusion of inpatient data from multiple states over a recent time frame, allowing results to be more broadly generalizable to the current practice. Although surgical care has undergone multiple changes in the 9 years over which this study was conducted, outcomes remained stable with only a minimal downtrend in complication rates, and thus the study findings are relevant to modern-day practice. To our knowledge, this is the largest study to date comparing sim-BTKA and staged-BTKA with over 60,000 patients. Limitations of the present study are its retrospective nature, which as mentioned precludes intention-to-treat analyses due to difficulties in identifying patients who were initially slated for staged surgery but did not go on to complete the second stage. In addition, this study was limited to variables included in the Healthcare Cost and Utilization Project database. Thus, it did not account for unmeasured variables such as specific surgeon technique, prosthesis type, the mode and duration of deep venous thrombosis prophylaxis, or CCI score. CCI score was calculated indirectly from patient comorbidities recorded through ICD-9 coding data. Furthermore, the ICD-9 coding system does not record laterality and thus we used the time of occurrence in order to associate complications such as infection and mechanical malfunction with a particular stage of surgery. Large, randomized, prospective studies are needed in order to further define the differences in outcomes between simultaneous and staged
surgery and to best prepare orthopedic surgeons and providers for the impending surge in demand for TKAs. Conclusions Despite a higher statistical odds of experiencing many adverse outcomes for patients who undergo sim-BTKA vs staged-BTKA, these outcomes are all uncommon and the absolute differences in perioperative risks between these 2 surgical options are small. These minimal differences in absolute risk and their interplay with patient-specific as well as surgery-specific factors should be taken into consideration when discussing the advantages and disadvantages of both options for bilateral knee arthroplasty, timing of staged surgery, relative risks of specific complications, and informing shared decision-making. Acknowledgments We thank Matthew Callahan for his assistance with the database, and we thank Karla Lindquist for her guidance with statistical analyses. References [1] Kurtz S, Ong K, Lau E, Mowat F, Halpern M. Projections of primary and revision hip and knee arthroplasty in the United States from 2005 to 2030. J Bone Joint Surg Am 2007;89:780. https://doi.org/10.2106/JBJS.F.00222. [2] Cross M, Smith E, Hoy D, Nolte S, Ackerman I, Fransen M, et al. The global burden of hip and knee osteoarthritis: estimates from the global burden of disease 2010 study. Ann Rheum Dis 2014;73:1323e30. https://doi.org/ 10.1136/annrheumdis-2013-204763.
6
E.L. Tsay et al. / The Journal of Arthroplasty xxx (2019) 1e6
[3] Memtsoudis SG, Hargett M, Russell LA, Parvizi J, Cats-Baril WL, Stundner O, et al. Consensus statement from the consensus conference on bilateral total knee arthroplasty group. Clin Orthop Relat Res 2013;471:2649e57. https:// doi.org/10.1007/s11999-013-2976-9. [4] Meehan JP, Danielsen B, Tancredi DJ, Kim S, Jamali AA, White RH. A population-based comparison of the incidence of adverse outcomes after simultaneous-bilateral and staged-bilateral total knee arthroplasty. J Bone Joint Surg Am 2011;93:2203e13. https://doi.org/10.2106/JBJS.J.01350. [5] Restrepo C, Parvizi J, Dietrich T, Einhorn TA. Safety of simultaneous bilateral total knee arthroplasty. A meta-analysis. J Bone Joint Surg Am 2007;89: 1220e6. https://doi.org/10.2106/JBJS.F.01353. [6] Fu D, Li G, Chen K, Zeng H, Zhang X, Cai Z. Comparison of clinical outcome between simultaneous-bilateral and staged-bilateral total knee arthroplasty: a systematic review of retrospective studies. J Arthroplasty 2013;28:1141e7. https://doi.org/10.1016/j.arth.2012.09.023. [7] HCUP Databases. Healthcare cost and utilization project (HCUP). agency for healthcare research and quality, rockville, MD. www.hcup-us.ahrq.gov/ sidoverview.jsp. Updated April, 2017. [accessed 19.04.19]. [8] Charlson ME, Pompei P, Ales KL, MacKenzie CR. A new method of classifying prognostic comorbidity in longitudinal studies: development and validation. J Chronic Dis 1987;40:373e83. [9] Bates D, Martin M, Bolker B, Walker S. Fitting linear mixed-effects models using lme4. J Stat Softw 2015;67:1. https://doi.org/10.18637/jss.v067.i01. [10] R The R Project Stat Comput n.d. https://www.r-project.org/. [Accessed 15 December 2017]. [11] Levit K, Wier L, Stranges E, Ryan K, Elixhauser A. HCUP facts and figures: Statistics on hospital-based care in the united states. http://www.hcup-us. ahrq.gov/reports.jsp; 2007. Updated 2009. [accessed 15.12.17]. [12] March LM, Cross M, Tribe KL, Lapsley HM, Courtenay BG, Cross MJ, et al. Two knees or not two knees? Patient costs and outcomes following bilateral and unilateral total knee joint replacement surgery for OA. Osteoarthr Cartil 2004;12:400e8. https://doi.org/10.1016/j.joca.2004.02.002. [13] Ritter MA, Harty LD. Debate: simultaneous bilateral knee replacements: the outcomes justify its use. Clin Orthop Relat Res 2004:84e6.
[14] Hadley S, Day M, Schwarzkopf R, Smith A, Slover J, Zuckerman J. Is simultaneous bilateral total knee arthroplasty (BTKA) as safe as staged BTKA? Am J Orthop 2017;46:E224e9. [15] Barrett J, Baron JA, Losina E, Wright J, Mahomed NN, Katz JN. Bilateral total knee replacement: staging and pulmonary embolism. J Bone Joint Surg Am 2006;88:2146e51. https://doi.org/10.2106/JBJS.E.01323. [16] Yoon H-S, Han C-D, Yang I-H. Comparison of simultaneous bilateral and staged bilateral total knee arthroplasty in terms of perioperative complications. J Arthroplasty 2010;25:179e85. https://doi.org/10.1016/j.arth.2008.11.103. [17] Hussain N, Chien T, Hussain F, Bookwala A, Simunovic N, Shetty V, et al. Simultaneous versus staged bilateral total knee arthroplasty: a meta-analysis evaluating mortality, peri-operative complications and infection rates. HSS J 2013;9:50e9. https://doi.org/10.1007/s11420-012-9315-7. ttir A, Lidgren L, Robertsson O. Higher early mortality with simul[18] Stef ansdo taneous rather than staged bilateral TKAs: results from the Swedish Knee Arthroplasty Register. Clin Orthop Relat Res 2008;466:3066e70. https:// doi.org/10.1007/s11999-008-0404-3. [19] Pulido L, Ghanem E, Joshi A, Purtill JJ, Parvizi J. Periprosthetic joint infection: the incidence, timing, and predisposing factors. Clin Orthop Relat Res 2008;466:1710e5. https://doi.org/10.1007/s11999-008-0209-4. [20] Peskun C, Mayne I, Malempati H, Kosashvili Y, Gross A, Backstein D. Cardiovascular disease predicts complications following bilateral total knee arthroplasty under a single anesthetic. Knee 2012;19:580e4. https://doi.org/10.1016/ j.knee.2011.09.010. [21] Bohm ER, Molodianovitsh K, Dragan A, Zhu N, Webster G, Masri B, et al. Outcomes of unilateral and bilateral total knee arthroplasty in 238,373 patients. Acta Orthop 2016;87:24e30. https://doi.org/10.1080/17453674.2016.1181817. [22] Chen A, Rasouli M, Vegari D, Huang R, Maltenfort M, Parvizi J. Staged bilateral total knee arthroplasty: time of the second side. J Knee Surg 2014;28:311e4. https://doi.org/10.1055/s-0034-1384215. [23] Yeh J, Chen J, Lee W, Chong H, Pang H, Tay D, et al. Identifying an ideal time frame for staged bilateral total knee arthroplasty to maximize functional outcome. J Knee Surg 2017;30:682e6. https://doi.org/10.1055/s0036-1597273.
E.L. Tsay et al. / The Journal of Arthroplasty xxx (2019) 1e6
6.e1
Appendix
Appendix A ICD-9 Codes for Complications. Complication
ICD-9 Codes
Death (30 d, 90 d, 1 y) Myocardial infarction (30 d) Ischemic stroke (30 d) Cardiac complications (30 d) Respiratory complications (30 d) Digestive complications (30 d) Urinary complications (30 d) Hematoma (30 d) Deep vein thrombosis (60 d)
Coded from discharge disposition ‘410.01’, ‘410.11’, ‘410.21’, ‘410.31’, ‘410.41’, ‘410.51’, ‘410.61’, ‘410.71’, ‘410.81’, ‘410.91’ ‘997.02’, ‘433.01’, ‘433.11’, ‘433.21’, ‘433.31’, ‘433.81’, ‘433.91’, ‘434.01’, ‘434.11’, ‘434.91’ ‘997.1’ ‘997.3’ ‘997.4’, ‘560.1’ ‘997.5’ ‘998.12’, ‘719.16’ ‘415.11’, ‘415.19’, ‘451.81’, ‘451.83’, ‘451.89’, ‘453.40’, ‘453.41’, ‘453.42’, ‘453.8’, ‘453.9’ ‘444.22’, ‘444.81’, ‘996.77’ ‘415.11’, ‘415.19’ Any of (‘996.66’, ‘996.67’, ‘998.59’) AND any of (‘00.80’, ‘00.81’, ‘00.82’, ‘00.83’, ‘00.84’, ‘80.06’, ‘80.16’, ‘80.76’, ‘80.86’, ‘80.96’, ‘81.55’, ‘86.05’, ‘86.22’) Any of (‘996.66’, ‘996.67’, ‘998.59’) WITHOUT any of (‘00.80’, ‘00.81’, ‘00.82’, ‘00.83’, ‘00.84’, ‘80.06’, ‘80.16’, ‘80.76’, ‘80.86’, ‘80.96’, ‘81.55’, ‘86.05’, ‘86.22’) Any of (‘718.36’, ‘718.56’, ‘996.40’, ‘996.41’, ‘996.42’, ‘996.43’, ‘996.44’, ‘996.45’, ‘996.46’, ‘996.47’, ‘996.49’, ‘996.77’, ‘996.78’) AND any of (‘77.86’, ‘78.55’, ‘78.67’, ‘79.06’,‘80.46’, ‘81.55’) Any of (‘718.36’, ‘718.56’, ‘996.40’, ‘996.41’, ‘996.42’, ‘996.43’, ‘996.44’, ‘996.45’, ‘996.46’, ‘996.47’, ‘996.49’, ‘996.77’, ‘996.78’) AND any of (‘83.91’)
Pulmonary embolism (60 d) Deep knee infection (1 y) Superficial knee infection (1 y) Major mechanical malfunction (1 y)
Minor mechanical malfunction (1 y)
ICD, International Classification of Diseases, Ninth Revision.