Introduction

Total knee arthroplasty (TKA) is a common surgical procedure for the end-stage knee osteoarthritis [1, 2], while the prevalence of chronic kidney disease (CKD) is increasing worldwide [3]. Recent studies suggest that the TKA patients with CKD carry higher risks of postoperative complications [4,5,6]. However, a single study compromises the reliability of the conclusions due to its relatively small amount of data and statistical power.

Kidney function is defined using the estimated glomerular filtration rate (GFR). The severity is classified into five stages based on the level of estimated GFR (stage I, > 90 mL/min; stage II, 60–89 mL/min; stage III, 30–59 mL/min; stage IV, 15–29 mL/min; stage V renal failure, < 15 mL/min) [7]. Patients with end-stage CKD must receive dialysis or kidney transplantation, which augment the potential risks of complications after TKA. In addition, the CKD is associated with the comorbidities such as anemia, diabetes mellitus, hypertension, weakened immune system. Each of them is an independent risk factor for postoperative complications [8]. DiMagno et al. [3] found that patients with stage III, IV, or V CKD are at greater risks of complications after TKA. Gwam et al. [4] found the dialysis-dependent patients are associated with a prolonged hospital stay, but do not carry the risk of 30-day complications. Antonia et al. [5] suggested stage III and IV CKD were associated with the major postoperative complications. Currently, no meta-analysis elucidated the outcomes of TKA in CKD patients.

The purpose of this meta-analysis was to review the current evidence in the literature to find out whether the CKD affects the infection, revision, transfusion, readmission, mortality, and the length of stay (LOS) after TKA. The primary outcomes were infection, revision, and mortality. The secondary outcomes were transfusion rate, the length of hospital stay, and readmission. This is the first meta-analysis to assess the outcomes of TKA in CKD patients.

Materials and Methods

Search strategy

The systematic literature review was structured to adhere to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement, which included the requirements deemed essential for the transparent reporting of results [9]. Ethical approval was not needed because all the data presented in this study were extracted from the published articles and did not cover any personal data. We searched the online databases including Medline, PubMed, Embase, and the Cochrane Library from their dates of inception to June 30, 2020. We searched the following terms: (Renal Insufficiency OR Kidney Insufficiency OR Kidney Failure OR Renal Failure OR Kidney Failure, Chronic OR End-Stage Kidney Disease OR End-Stage Renal Disease OR Dialysis OR Hemodialysis) AND (Arthroplasty, Replacement, Knee OR Arthroplasty, Knee Replacement OR Knee Replacement Arthroplasty OR Knee Arthroplasty, Total OR Total Knee Arthroplasty OR Total Knee Replacement OR Knee Arthroplasty OR Arthroplasty, Knee OR Arthroplasties, Knee Replacement OR Replacement Arthroplasty, Knee). Publication language was limited to English. The references of the selected articles were also searched and reviewed.

Eligibility criteria

The articles included in the meta-analysis met all of the following inclusion criteria (in the PICOS order): (1) population: patients undergoing primary TKA or minimally invasive TKA; (2) intervention: CKD group; (3) comparison intervention: non-CKD group; (4) outcome measures: at least one of the following outcomes was reported: infection, revision, transfusion, the length of stay (LOS), re-admission, and mortality; (5) study design: prospective study, retrospective study or registry study. The articles that did not assessthe outcomes mentioned above were excluded. The articles evaluating the revision surgery or unicompartmental knee arthroplasty, involving no comparison between CKD and non-CKD or combining outcomes of TKA and total hip arthroplasty were excluded. The conference abstracts, case reports, biochemical trials, letters, and reviews were also excluded.

Data extraction

Two reviewers (CJ and YY) independently checked the full text of the selected articles. Raw information including characteristics of the articles (author, publication year, study design, and follow-up period) and patients’ demographic details (the number of patients, average age, gender ratio, and stage of CKD) were extracted. The primary outcomes were the incidence of postoperative complications, including dislocation, infection, deep vein thrombosis (DVT), pulmonary embolism (PE), revision surgeries, and mortality. The secondary outcomes included re-admission, transfusion, and duration of hospitalization. If data were incomplete or could not be extracted directly, we contacted the corresponding authors to ensure the integrity of the data.

Statistical analysis

We used the Review Manager software (v 5.3; Cochrane Collaboration) to perform the meta-analysis. The extracted data were independently entered into the Review Manager by one author and independently checked by another author. The results of the selected studies were pooled for meta-analysis when two or more results were available. We applied the Mantel-Haenszel method to compute the pooled odds ratio (OR). An OR with a 95% confidence interval (CI) or a mean difference with a 95% CI was categorized as dichotomous outcomes or continuous outcomes, respectively. A P value of < 0.05 was deemed to be statistically significant. We used the Q and chi² tests to estimate the P value and I² of the heterogeneity measures. All outcomes were pooled on the random-effect model.

Quality evaluation

Because no randomized trials were included, the Newcastle-Ottawa scale (0 = very poor to 9 = rigorous) was applied to evaluate the quality of non-randomized studies. The Newcastle-Ottawa scale-based methodological quality assessment was conducted in three domains: study selection, intergroup comparability, and exposure (Table 1). A higher score indicated a better quality of an article. Two reviewers (CJ and YY) independently assessed the included articles, and disagreements were resolved by discussion with a third reviewer (WS). The sensitivity analysis was also conducted to evaluate whether any single study had the weight to skew on the whole estimate and data. Publication bias analyses were not performed due to the relatively scant literature.

Table 1 Newcastle-Ottawa scale
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Results

Search results and study characteristics

A total of 881 articles were initially identified from the online registerry databases, and 858 articles were excluded after primary review of the titles and abstracts. After further full-text evaluation, 16 articles that did not meet the inclusion criteria were excluded. Finally, 7 articles were included in the meta-analysis (Fig. 1) [6, 10,11,12,13,14,15]. The baseline characteristics of the studies and patient demographic details are shown in Table 2. Among them, 6 articles [6, 10,11,12, 14, 15] were defined as having CKD using the international classification of diseases (ICD) or diagnostic codes on their electronic medical records or registry databases. One article [13] was defined as having CKD by calculating the estimated GFR (< 60 mL/min/1.73 m2 ; stage II-V). All 7 studies were matched control studies. The Newcastle-Ottawa scales of the included studies ranged from 6 to 9, indicating that the quality of the included studies was at the upper-middle level, and the outcomes of the included studies could be considered to be reliable (Table 1). The 7 studies included a total of 4,329,455 patients. Among them, 14,515 patients (TKA group; 0.33 %) suffered from chronic kidney disease prior to TKA, and 4,314,940 patients (no-TKA group; 99.66 %) had not. The mean age of the two groups were similar. Of the 7 studies, the percentage of female patients ranged from 27 to 77 %, and the mean follow-up periods lasted 2 to 3.4 years.

Fig. 1
figure 1

PRISMA flowchart. A total of 881 studies were evaluated. Titles and abstracts were assessed, and 23 full-text articles were eligible for evaluation. Sixteen articles were excluded, and 7 articles remained for the final analysis. TKA: total knee arthroplasty; THA: total hip arthroplasty; CKD: chronic kidney disease

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Table 2 Characteristics of the included studies
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Meta-analyses

Venous thrombus embolism (PE and DVT) were reported in 2 studies [6, 14], the incidences of VTE were 1.09 % in CKD group and 1 % in non-CKD group (OR 1.08, 95 % CI 0.80–1.47, P = 0.61) (Fig. 2). Postoperative infection was reported in 5 studies [6, 10,11,12, 14], but there was no significant difference between the groups (OR 3.77, 95 % CI 0.86–16.52, P = 0.08) (Fig. 3a). Revision surgeries were reported in 3 studies [6, 10, 15], but there was no significant difference between the groups (OR 1.12, 95 % CI 0.95–1.31, P = 0.19) (Fig. 3b). Blood transfusion was reported in 3 studies [11,12,13], and the incidences were 37 % (707 of 1903 patients) in CKD group and 19 % (803,664 of 4,181,644 patients) in non-CKD group (OR 5.22, 95 % CI 1.95–13.98, P = 0.001) (Fig. 3c). The LOS was assessed in 2 studies [11, 13], including 4,183,502 patients. There was no significant difference between the groups (mean difference = 1.35, 95 % CI –0.12–2.82, P = 0.07) (Fig. 4a). Re-admission was assessed in 2 studies [6, 14]. The pooled results showed that the CKD group had a higher re-admission rate than the non-CKD group (OR 1.95, 95 % CI 1.27–3.00, P < 0.0001) (Fig. 4b). Postoperative mortality was assessed in 3 studies [1, 11, 14]. The pooled results indicated that the CKD group was associated with higher postoperative mortality, compared to the non-CKD group (OR 3.09, 95 % CI 1.77–5.43, P < 0.0001) (Fig. 4c). Sensitivity analysis was conducted among the outcomes with a high heterogeneity, and showed that removing any single study did not change the statistical results.

Fig. 2
figure 2

Forest plots of the VTE (both PE and DVT) between CKD group and non-CKD group after TKA

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Fig. 3
figure 3

(a) Forest plots of the infection between CKD group and non-CKD group after TKA; (b) Forest plots of the revision between CKD group and non-CKD group after TKA; (c) Forest plots of the transfusion between CKD group and non-CKD group after TKA

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Fig. 4
figure 4

(a) Forest plots of the length of stay between CKD group and non-CKD group after TKA; (b) Forest plots of the re-admission between CKD group and non-CKD group after TKA; (c) Forest plots of the mortality between CKD group and non-CKD group after TKA

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Discussion

Recent studies showed that the prevalence rates of CKD in TKA patients are between 6 % and 27 % [16, 17]. In this study, we found the CKD patients carried higher risks of postoperative mortality and re-admission, compared to the non-CKD patients. The CKD patients had a higher probability of postoperative transfusion than their non-CKD counterparts. However, the CKD did not affect the risks of postoperative infection, revision or LOS.

Ponnusamy et al. [11] found the CKD affected bone volume, mineralization, linear growth, and strength [18]. Tan et al. [8] demonstrated the patients with end-stage CKD carried a higher risk of VTE, because the increased inflammatory state produces the hypercoagulability [19]. The chronic inflammation produces excessive fluid in the soft tissue surrounding the knee and increases the risks of periprosthetic infection and revision surgery [20]. The CKD is often associated with a poor nutritional status, electrolyte disorders, decreased immunity, and anemia [1, 8, 21, 22]. Those factors also increase the risk of postoperative infection. McCleery et al. [10] reported that the CKD increased the risk of early periprosthetic infection by 50 %.

However, there are different conclusions. Chen et al. [1] retrospectively evaluated 15 CKD patients (18 knees) who underwent TKA with antibiotic-loaded cement, and no infection was reported after a mean follow-up period of 25 months. Ling et al. [23] evaluated 13 CKD patients (18 knees) who underwent TKA, and no infection was found after a mean follow-up period of 5 years. Warth et al. [16] found that there were no differences between the CKD patients and non-CKD patients regarding the infectious surgical site complications, such as superficial or deep wound infection, organ space infection or wound dehiscence. Several studies revealed the combined use of antibiotic-loaded bone cement and systemic antibiotic therapy can decrease the risk of postoperative infection, but similar infection rates were reported in both CKD and non-CKD patients [1]. Wang et al. [24] did not find an increased infection rate even in the patients who experienced a long period of dialysis vintage.

McCleery et al. [10] found the patients on dialysis had an increased revision rate within one year after TKA, but the result is similar to the revision rate of non-CKD patients. However, Miric et al. [6] found there was no difference between the early and later revision rates. The most common cause of revision TKA is the periprosthetic joint infection, accounted for 62 % of all revision TKAs [25]. We found the similar revision rates in the CKD and the non-CKD patients. However, confirming the actual causes of revision is often difficult, which affects the assessment of the actual revision rates.

Patients with CKD and on long-term dialysis are often associated with renal anemia, metabolic imbalance, elevated risk of bleeding, and poor vascular circulation [26]. Graves et al. [27] showed that the degree of anaemia was more pronounced in patients with more advanced CKD. Moreover, the intra- and postoperative blood loss ranges from 800 mL to 1000 mL [28]. Kaiser et al. [29] found the CKD patients had a higher rate of transfusion (24 %) compared to non-CKD patients (8 %). Our study also supports this conclusion.

Death is a rare and devastating complication of TKA, but the early reported mortality rates range from 17 to 58 % in CKD patients [6, 30, 31]. Ponnusamy et al. [11] reported athe mortality rate of 1 % in dialysis-dependent patients. Several articles reported that the CKD is the independent risk factor of mortality in the early 90 days, and is the independent risk factor of morbidity in the early 30 days [13, 32, 33]. Warth et al. [16] demonstrated the incremental mortality was associated with an increased risk of postoperative pulmonary and cardiovascular complications. Our meta-analysis supports these findings.

Our sensitivity analysis was conducted among the outcomes with a high heterogeneity. Removing any single study  did not change the statistical results. Therefore, we believe our findings in this meta-analysis are reliable.

Our meta-analysis has limitations. First, the retrospective studies included may lead to potential biases. Second, analyzing all CKD patients together without considering the severity may cause sampling bias, because there is a dose-dependent relationship between the severity of CKD and outcomes of TKA [6]. Third, owing to the relatively short duration of follow-up, infection and revision rates were potentially underestimated. Fourth, the presence of publication bias is likely to decrease our confidence in the meta-analytic findings [12]. Fifth, each comorbidity (diabetes, heart failure, peripheral vascular disease, hypertension, etc.) is analysed as an independent risk factor, but overlooking the fact that the patients with multimorbidities may lead to selection bias [3]. Sixth, in the future, more high quality and matched control studies should be conducted to improve the statistical efficiency and precision.

Conclusions

Compared to the non-CKD patients, CKD patients carry higher risks of mortality and re-admission after TKA, as well as a higher incidence of transfusion. However, the CKD may not increase the risk of infection or revision, nor the duration of hospitalization.