Introduction

Total knee arthroplasty (TKA) is an efficient and common procedure used to treat advanced osteoarthritis of the knee. Geriatric patients make up the majority of TKA patients, with insurance beneficiaries accounting for around 75% of TKA procedures [1]. According to Cram et al. [2], between 1991 and 2010 there was a 161% rise in yearly TKA volume. This rise is attributable to the elderly population’s improvement in function, independence, and pain as well as the growing acceptance of invasive therapy [3, 4]. For the surgical management of bilateral knee arthritis, there is still debate regarding whether to do a simultaneous or phased total knee arthroplasty. When the procedure is performed at the same time, there is a higher risk of significant complications or even death, according to various studies. However, some researchers are of the opinion that there is little to no evidence linking simultaneous TKA to an increase in risks or complications. There have been inconsistent findings when simultaneous bilateral TKA and staged bilateral TKA have been compared in a few randomized and nonrandomized controlled trials [5,6,7,8].

After having a complete knee arthroplasty, four out of five patients are satisfied with the results [6]. However, geriatric patients with comorbidities may have higher risks and expenditures, which could prevent them from having as many elective orthopaedic surgeries. Patients who are 85 years or older are 41% less likely than younger patients to undergo TKA [1]. Older patients who did not have surgery made up nearly half of those who were not given TKA [7]. Age has a variable impact on surgical outcomes, according to previous studies [7,8,9,10,11], and there is no clear relationship between age and TKA candidacy.

Because of ethical concerns, it is challenging to conduct a controlled randomized trial of patients with bilateral knee arthritis. Furthermore, because patients with higher comorbidity are frequently thought to be undesirable candidates for simultaneous TKA and are typically excluded from studies of those procedures, many of the research addressing the problems linked to bilateral TKA may have selection bias. Last but not least, and perhaps most significantly, the majority of the studies had rather small sample sizes and were likely underpowered to detect differences between the two treatments choices due to the relative rarity of serious complications following TKA.

Through meta-analysis, data can be gathered to address important issues like the safety of bilateral TKA in patients over 75 years of age. We gathered the available published data using stringent selection criteria to see if the occurrence of severe complications and mortality varied between bilateral and staged TKA. To assess the safety of simultaneous bilateral TKA compared with staged bilateral TKA in patients, all randomized and nonrandomized trials that compared the two procedures were considered. A more accurate method of patient selection would be made possible by a greater comprehension of the advantages and disadvantages of TKAs in this group. In order to clarify the effect of age on total knee arthroplasty, we systematically reviewed and evaluated studies that investigated the association of age on surgical outcomes.

Materials and methods

Study selection and information source

In this study, we adhered to the PRISMA 2020 guidelines and the Cochrane Handbook for systematic reviews and meta-analyses [12, 13]. We conducted a comprehensive literature search using EMBASE, PubMed (MEDLINE), Cochrane, and Google Scholar to find peer-reviewed articles on bilateral TKA. Additionally, we manually searched the references of relevant articles, tables of contents from major orthopedic journals (2010–2023), and bibliographies of key arthroplasty textbooks, including “The Adult Knee,” “Campbell’s Operative Orthopaedics,” and “Joint Replacement Arthroplasty.“

We screened study titles and abstracts for potential inclusion, considering all studies comparing the safety of simultaneous bilateral TKA with staged bilateral TKA, irrespective of diagnosis, surgical approach, or prosthesis type. For studies with overlapping patient populations, the one with the longest follow-up was selected. Data on population characteristics, interventions, and outcomes were extracted, though variables such as weight, race, BMI, comorbidities, prior knee surgeries, surgical methods, anesthesia techniques, perioperative antibiotics, thromboembolic prophylaxis, and postoperative rehabilitation details were inconsistently reported. Our primary outcomes were mortality and major complications, including deep vein thrombosis, pulmonary embolism, neurological complications, and cardiac issues.

Data extraction

Every relevant detail that was presented in the studies was extracted after an independent evaluation, including but not limited to demographics, prior procedures, and information on thromboembolic and infection prevention, patient satisfaction, functional outcome, and complication rate. In each report, details were obtained regarding the characteristics of the investigated population. The number of patients who underwent a simultaneous or staged procedure, as well as any complications that were indicated and the requirement for revision surgeries, were also noted.

Statistical analysis

Odd ratios (ORs) or standard mean differences (SMDs) with associated 95% confidence intervals (CI) were estimated and pooled across trials to evaluate the disparity between the 2 approaches, with a value of P < 0.05 being considered significant. Using a forest plot, the meta-analysis of relevant variables was graphically summarized.

Publication bias was assessed by ROBIS tool. All analyses were performed using the RevMan 5.3 software.

The last search was done in September 2023, and the following search terms were used: total knee arthroplasty (TKA), complications following TKA, bilateral TKA, and simultaneous bilateral vs. staged bilateral TKA. Additionally, we looked for any potentially pertinent studies using the “related articles” option. This method of searching produced 751 non-duplicated articles [Fig. 1].

Fig. 1
figure 1

PRISMA flowchart of the Meta-analysis

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Results

In the search for research on the variables that affect Simultaneous bilateral TKA in patients, 848 citations were found; 751 citations were included after screening for duplicates. When inclusion and exclusion criteria were applied to abstracts, 648 articles were eliminated from the review. Following the application of inclusion and exclusion criteria to 103 full-length manuscripts, 24 articles were selected for review. Table 1 shows the relevant findings from these 24 publications.

Table 1 Characteristic Features of the Included Studies
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The risk of bias was assessed using the ROBIS tool, and the findings revealed that the methods and outcomes of the literature search qualified for a low risk of bias [Table 2].

Table 2 ROBIS Tool for assessing risk of bias in meta-analysis
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Eligible studies

A total of 24 articles were selected for inclusion in the meta-analysis [Table 1]. The published reports included information on 1, 86,054 patients. There were 2,18,385 patients included in the meta-analysis. 93,074 patients underwent simultaneous bilateral TKA, and 125,311 patients underwent staged bilateral TKA. Data on the rates of deep venous thrombosis in the two groups were provided by twelve articles [17, 18, 23,24,25,26,27,28,29,30,31, 35]. Thirteen articles reported on the prevalence of pulmonary embolism in the population under study [17, 18, 21, 23,24,25,26,27,28,29,30,31, 35]. The prevalence of cardiac complications was calculated using twelve trials [15,16,17,18, 24, 25, 27, 29, 30, 35,36,37]. Twenty studies provided data on the rate or prevalence of mortality in the sample [14, 15, 17, 18, 20,21,22,23,24,25,26,27,28,29,30, 32, 33, 35,36,37]. The two groups of patients were compared in terms of the prevalence of the five most serious complications: deep venous thrombosis, pulmonary embolism, cardiac events, neurological complications and mortality. The analysis revealed that, even though a large number of studies on this topic have been published, the overall conclusions are inconclusive. The reporting of the results, specifically the final odds ratio, varies significantly across the articles. The majority of the articles do not specify the exact age criteria for TKA.

Deep venous thrombosis

The risk of a deep venous thrombosis event was lower in patients after staged bilateral TKA, and this finding was statistically significant (P value < 0.00001, Odds ratio [OR] 1.31, 95% Confidence interval [CI] 1.17–1.46) [Fig. 2]. The pooled odds ratio was 1.31 overall. For a sample size of 1,33,000 patients the highest odds ratio was 3.74 in a study that did not have a significant impact on the overall result.

Fig. 2
figure 2

Forest plot for Deep venous thrombosis following simultaneous bilateral total knee arthroplasty

OR – Odd’s ratio, CI – Confidence interval, df – degree of freedom

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Pulmonary embolism

Similar to the findings for deep venous thrombosis, the risk of pulmonary embolism was the higher in patients who had simultaneous bilateral TKA than in patients who had staged bilateral TKA (P value < 0.00001, OR 1.58, 95% CI 1.30–1.91) [Fig. 3]. Three of the articles made the most significant contributions to the overall calculation. After bilateral TKA, the highest odds ratio for pulmonary embolism was 12.05.

Fig. 3
figure 3

Forest plot for Pulmonary embolism following simultaneous bilateral total knee arthroplasty

OR – Odd’s ratio, CI – Confidence interval, df – degree of freedom

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Cardiac complications

The likelihood of cardiac complications varied little between groups as well. The analysis of twelve articles revealed no increase in the prevalence of cardiac events in patients who underwent simultaneous bilateral TKA as compared to staged bilateral TKA (P value = 0.60, OR 0.93, 95% CI 0.70–1.23) [Fig. 4]. The highest odds ratio recorded was 1.64.

Fig. 4
figure 4

Forest plot for Cardiac complications following simultaneous bilateral total knee arthroplasty

OR – Odd’s ratio, CI – Confidence interval, df – degree of freedom

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Mortality

The prevalence of mortality significant in the population that had undergone simultaneous bilateral TKA as compared to those who underwent staged bilateral TKA (P value < 0.00001, OR 1.86, 95% CI 1.53–2.26) [Fig. 5].

Fig. 5
figure 5

Forest plot for Mortality following simultaneous bilateral total knee arthroplasty

OR – Odd’s ratio, CI – Confidence interval, df – degree of freedom

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Neurological complications

The prevalence of neurological complications were found to be higher in patients undergoing simultaneous bilateral TKA (P value < 0.002, OR 1.44, 95% CI 1.14–1.82) [Fig. 6].

Fig. 6
figure 6

Forest plot for Neurological complications following simultaneous bilateral total knee arthroplasty

OR – Odd’s ratio, CI – Confidence interval, df – degree of freedom

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Discussion

TKA remains one of the most effective orthopaedic surgical procedures and is considered extremely safe. Although the majority of patients with knee arthritis undergo unilateral TKA, patients with symptomatic arthritis of both knees are not uncommon. The orthopaedic surgeon must then determine whether bilateral simultaneous TKA is a safe procedure to perform in this circumstance. Furthermore, the majority of patients suffering from knee arthritis are over the age of 60 years. Simultaneous Bilateral TKA in these patients is still being debated. There is a need to decide whether simultaneous TKA in patients is safe.

There are numerous benefits to performing simultaneous bilateral TKA in patients during a single anaesthetic session. Some of the benefits of this approach include patient convenience, a shorter length of stay in the hospital, and a potentially shorter period of rehabilitation and disability. On the other hand, some surgeons are hesitant to perform simultaneous bilateral TKA during a single anaesthetic session due to concerns about increased complications. When an orthopaedic surgeon searches the literature for information on the safety of simultaneous bilateral TKA, he or she may come across contradictory results. The apparent conflict noted in the literature could be caused by a number of factors. Because complications like pulmonary embolism are uncommon, the majority of studies have a type-II statistical error due to a small patient population. Furthermore, the effect of probable, and significant, selection bias cannot often be gleaned from these studies.

The investigators of a recent study attempted to overcome the aforementioned limitations by including a large patient sample [35]. In that study, patients who had simultaneous bilateral TKA had a higher incidence of pulmonary embolism than patients who had staged bilateral TKA. The incidence of pulmonary embolism in the first three months after arthroplasty was 1.45% in patients who had a single procedure compared to 0.77% in patients who had a staged bilateral TKA. Despite its strengths, this study suffered from the limitations inherent to analyses involving the Medicare database, as previously outlined. The Medicare database lacks important clinical information such as operative details. Hence, it was not possible for the investigators in that study to distinguish adequately between staged and simultaneous bilateral procedures.

As a result, this meta-analysis was carried out in order to combine data from a number of qualified studies in order to determine the prevalence of serious complications, including death, after bilateral TKA. The meta-analysis collected data and discovered that major complications such as pulmonary embolus, neurological events, deep venous thrombosis and death were significant after simultaneous bilateral TKA. The prevalence of cardiac complications appeared to be slightly lower after simultaneous bilateral TKA compared to staged bilateral TKA, but this difference was not statistically significant. This complication was not reported in all of the studies included in this meta-analysis. Although it was not a direct finding of this study, one could conclude that patients with concurrent cardiopulmonary conditions may not be good candidates for simultaneous bilateral TKA, even with recent advances in surgical and anaesthesia techniques.

Limitations

This study thoroughly examines the existing research on simultaneous bilateral TKA vs. staged bilateral TKA and the complications associated with the procedure. This study is unusual in its methodology and findings since, to our knowledge, there aren’t any reviews conducted in accordance with PRISMA standards that attempt to determine whether simultaneous bilateral TKA is safe patients. This study does, however, contain certain restrictions. Because of the difficulty in extracting the relevant information, this meta-analysis did not distinguish between simultaneous and staged bilateral total knee arthroplasty as a whole. Another potential limitation of this meta-analysis is related to the strict criteria for inclusion of randomized and comparative studies, as some potentially relevant studies may have been excluded. This step was necessary in order to eliminate important confounding variables. Finally, the meta-analysis was intended to evaluate the prevalence of major and life-threatening complications associated with simultaneous bilateral TKA. Hence, information on other complications such as periprosthetic infection or functional recovery was not sought. The majority of the studies did not provide information pertinent to these problems.

Based on our results, we recommend that the strategy for performing bilateral TKA should be carefully selected based on patient age, comorbidity profile and preference. Patients should be carefully counseled regarding the respective incidence of complications and consequent risks associated with each respective strategy. Further matched prospective studies comparing both clinical outcomes and patient reported outcomes following simultaneous bilateral TKA and staged bilateral TKA are required.

Conclusion

Staged bilateral TKA is associated with less complication rates as compared to simultaneous bilateral TKA. Hence, patients should be counselled and selected based on the risks respective to each strategy. However, there is a need for high-quality, prospective studies to better evaluate the clinical, functional and cost effectiveness of simultaneous bilateral TKA compared to staged bilateral TKA.