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Knee Surgery: A Meta Analysis Poised To Drive Down Surgical Site Infection Rates

Knee Surgery: A Meta Analysis Poised To Drive Down Surgical Site Infection Rates


This systematic review and meta-analysis aimed to determine the prevalence of surgical site infection (SSI) following knee surgery and identify associated risk factors. A comprehensive search of international electronic databases, including Scopus, PubMed, and Web of Science, as well as Persian databases, was conducted up to October 1, 2023. Keywords such as ‘Prevalence,’ ‘Surgical wound infection,’ ‘Surgical site infection,’ and ‘Orthopedics’ were utilized. The quality of included studies was assessed using the Appraisal tool for Cross-Sectional Studies (AXIS tool).


The study encompassed data from 11,028 individuals across seven selected studies. The collective prevalence of SSI after knee surgery was found to be 3.0%, with a confidence interval of 1.2% to 7.5%. Subgroup analyses revealed varying prevalence rates across different patient populations, particularly among those with diabetes mellitus (DM), hypertension (HTN), and a history of tobacco use.


For patients with DM, the combined prevalence of SSI after knee surgery was 5.1%, while for patients with HTN, it was 1.8%. Additionally, patients with a history of tobacco use had a collective SSI prevalence of 4.8%. Subgroup analysis by country showed a prevalence of 3.0% in China and 2.0% in the USA.


The variations in SSI prevalence among different studies suggest the influence of various risk factors among knee surgery patient populations. To mitigate the impact of SSI on knee surgery patients, tailored interventions are recommended. These findings underscore the importance of understanding and addressing risk factors to improve postoperative outcomes.


In the realm of orthopedic surgery, a surgical site infection (SSI) manifests as an infection occurring within 30 days post knee surgery in cases without fixation devices, or within 1 year if metallic implants are present. SSIs are significant complications across orthopedic and various surgical domains, influenced by factors such as the expanding scope of orthopedic procedures, their complexity, and frequent implant utilization. Incidence rates vary widely, ranging from 1.4% to 41.9%, posing unique challenges in treatment due to the complexities of bone and joint infections and a substantial long-term recurrence risk of 10%–20%. These infections can be superficial or deep, impacting outer layers of incisions or penetrating deeper structures like muscles and joints.


Preventable by nature, SSIs have garnered attention in recent guidelines, emphasizing the imperative to mitigate this costly complication, particularly in orthopedic procedures including knee surgeries. Understanding associated risk factors is crucial for effective prevention. Common factors include prolonged surgery duration, diabetes, smoking, and obesity, though their definitive impact on SSIs post-knee surgery remains unclear. To address this gap, a systematic review and meta-analysis were undertaken to delineate SSI prevalence and associated factors in knee surgery patients.


This systematic review and meta-analysis adhered to the PRISMA checklist for Preferred Reporting Items. A thorough search strategy encompassed international electronic databases like Scopus, PubMed, and Web of Science, as well as Persian databases such as Iranmedex and the Scientific Information Database (SID). Utilizing Medical Subject Headings keywords like “Prevalence,” “Surgical wound infection,” “Surgical site infection,” and “Orthopaedics,” the search spanned records up to October 1, 2023, with equivalent Persian keywords also considered. Two researchers independently conducted this extensive search, excluding grey literature, including expert comments, conference presentations, theses, and ongoing research. EndNote facilitated data management. Selection criteria involved initial screening of titles and abstracts, followed by identification and removal of duplicate papers. Discrepancies were resolved by a third researcher, with thorough reference examination to prevent data loss.


Data extraction encompassed various details such as author name, publication year, study location, sample size, demographics, surgery specifics, comorbidities, and lifestyle factors. Quality assessment employed the Appraisal tool for Cross-Sectional Studies (AXIS tool), comprising 20 items scored on a two-point Likert scale. Quality was categorized as high, fair, or low based on correct response percentages. Two researchers independently conducted data extraction and quality evaluation, ensuring rigor and reliability.

Inclusion Criteria

This systematic review delved into the body of published cross-sectional studies, encompassing both Persian and English literature, to investigate the prevalence of surgical site infections (SSI) among patients who underwent knee surgery.

Exclusion Criteria

The analysis excluded reviews, case studies, conference materials, letters to the editor, legal proceedings, and qualitative research. This decision was made to maintain the integrity and focus of our study on pertinent and empirically grounded sources. By excluding these types of materials, we ensure that our findings are based on rigorous and substantive research, thereby enhancing the reliability and validity of our conclusions.

Statistical Analysis

In this analysis, version 3 of the CMA program was utilized, employing a weighting method based on inverse variance for each study. To evaluate the variation among the studies, we utilized a forest plot to visually represent heterogeneity. We gathered data on sample sizes and the frequency of SSIs from each study to compute the overall effect size.


The degree of heterogeneity was measured using I² statistics, where values of 25%, 50%, and 75% indicated mild, moderate, and high heterogeneity respectively. Given significant variability in the results, we applied a random effects model. Subgroup analyses were performed for study-specific variables such as location to delve into the prevalence of SSI.


Additionally, a sensitivity analysis was conducted to evaluate the impact of excluding each study on the overall prevalence of SSI. This approach ensures a comprehensive understanding of the data and enhances the robustness of our findings.



The initial database search for a systematic review and meta-analysis yielded 1295 studies. After removing duplicates, 1068 papers remained. Following a thorough review of titles and abstracts, 899 studies were excluded for not aligning with the study’s objectives, and 120 studies were excluded due to various non-research-related content. After examining the full text of 44 studies, 20 were eliminated due to suboptimal research design or unsuitable results, and 17 were removed for lacking pertinent data. Ultimately, seven studies were included, comprising 11,028 individuals who underwent knee surgery, with an average age of 43.30 years and a male gender proportion of 62.50%.


All included studies were of high quality, with one study not reporting funding sources or conflicts of interest. The collective prevalence of surgical site infections (SSI) in patients who underwent knee surgery across the seven included studies was determined to be 3.0%. Although the odds ratio for SSI prevalence in men was higher than in women, this difference was not statistically significant.


Prevalence of SSI after knee surgery was also analyzed based on other risk factors. Patients with diabetes mellitus (DM) showed a prevalence of 5.1%, patients with hypertension (HTN) had a prevalence of 1.8%, and patients with a history of tobacco use had a prevalence of 4.8%.


Subgroup analysis by country revealed a prevalence of 3.0% in China and 2.0% in the USA. Sensitivity analysis was conducted by systematically removing one study at a time to assess its impact on overall results and heterogeneity between studies.


Publication bias was evaluated using the Egger regression test, which did not show any signs of bias in the prevalence of SSIs among patients with DM or HTN. However, there was suggested publication bias in the prevalence of SSI among patients with a history of tobacco use.


This comprehensive analysis provides valuable insights into the prevalence of SSIs following knee surgery and highlights potential risk factors associated with these infections.


This systematic review and meta-analysis aimed to investigate the prevalence of surgical site infections (SSIs) in individuals undergoing knee surgery. The study discovered that SSIs occurred in approximately 3.0% of patients undergoing knee surgery. SSIs not only affect patients physically but also impact them emotionally and financially, placing a burden on both patients and their families. Orthopedic surgeries, including knee surgery, are associated with a risk of SSIs, although this risk varies depending on factors such as surgical site locations.


The study compared its findings with previous investigations, revealing varying prevalence rates of SSIs in different types of orthopedic surgeries. Factors such as gender, comorbidities like diabetes mellitus (DM), and tobacco use were found to influence the occurrence of SSIs. For instance, men undergoing foot and ankle surgery exhibited a higher SSI prevalence compared to women, although this difference did not reach statistical significance. Additionally, patients with DM and smokers were observed to have elevated SSI prevalence rates.


The increased occurrence of SSIs in patients with DM and smokers can be attributed to various factors, including compromised immune function and impaired wound healing. Healthcare providers often implement additional measures, such as optimizing blood sugar levels and advising smoking cessation, to reduce the likelihood of SSIs in these patients.


However, the study acknowledged several limitations, including variability among included studies and potential publication bias. Recommendations for future research include conducting extensive prospective cohort studies focused on knee surgery patients and assessing the long-term consequences of SSIs. Moreover, randomized controlled trials are essential to evaluate the efficacy of interventions aimed at reducing SSI rates in knee surgery patients, such as preoperative optimization of comorbidities and standardized perioperative antibiotic prophylaxis.


In conclusion, the study found that the prevalence of SSIs in knee surgery patients was approximately 4.4%, with variations attributed to various factors. Tailored interventions addressing patient-specific risk factors are recommended to mitigate the impact of SSIs and enhance surgical outcomes in this patient population.

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