The Seasonal Variability of Surgical Site Infections in Knee and Hip Arthroplasty

Seasonal Impact on Wound Healing and Surgical Site Infections after Reduction Mammoplasty

Background: The incidence of reduction mammoplasty has been steadily increasing over recent decades. Surgical site infections (SSIs) represent a common yet preventable complication across surgical disciplines. Studies across various surgical specialties have indicated a seasonal influence on SSIs, primarily correlated with higher temperatures and humidity. However, there remains a scarcity of clear data regarding the seasonal effects on complications specifically in breast surgery. Methods: We conducted a retrospective review encompassing all patients who underwent primary bilateral reduction mammoplasties at our institution between 1 June 2016, and 1 September 2019. The data collected included patient demographics, surgical details, and postoperative complications. The rates of SSIs and wound healing disturbances (WHDs) were correlated with local meteorological data at the time of surgery. Results: A total of 808 patients (1616 breasts) met the inclusion criteria. The mean age was 41 ± 14.8 years, with a mean BMI of 28.9 ± 5.2 kg/m2 and a mean follow-up duration of 8.9 ± 9.8 months. Nineteen cases (2.35%) of surgical site infections and 77 cases (9.52%) of wound healing disturbances were reported. No statistically significant increase in the risk of SSIs (p = 0.928) or WHDs (p = 0.078) was observed during the warmer months of the year. Although no specific risk factors were identified for surgical site infections, both resection weight (p < 0.001) and diabetes mellitus (p = 0.001) demonstrated increased risks for wound healing disturbances. Conclusions: While seasonal temperature variations have been shown to impact SSIs and WHDs in body contouring procedures, our findings suggest that breast reduction surgery may not be similarly affected.

Contrasting seasonality of the incidence of incisional surgical site infection after general and gastroenterological surgery: an analysis of 8436 patients in a single institute

BACKGROUND

While seasonality of hospital-acquired infections, including incisional SSI after orthopaedic surgery, is recognized, the seasonality of incisional SSI after general and gastroenterological surgeries remains unclear.

AIM

To analyse the seasonality and risk factors of incisional SSI after general and gastroenterological surgeries.

METHODS

This was a retrospective, single-institute, observational study using univariate and multivariate analyses. The evaluated variables included age, sex, surgical approach, surgical urgency, operation time, wound classification, and the American Society of Anesthesiologists physical status (ASA-PS).

FINDINGS

A total of 8436 patients were enrolled. General surgeries (N = 2241) showed a pronounced SSI incidence in summer (3.9%; odds ratio (OR): 1.87; 95% confidence interval (CI): 1.05-3.27; P = 0.025) compared to other seasons (2.1%). Conversely, gastroenterological surgeries (N = 6195) showed a higher incidence in winter (8.3%; OR: 1.38; 95% CI: 1.10-1.73; P = 0.005) than in other seasons (6.1%). Summer for general surgery (OR: 1.90; 95% CI: 1.12-3.24; P = 0.018) and winter for gastroenterological surgery (1.46; 1.17-1.82; P = 0.001) emerged as independent risk factors for incisional SSI. Open surgery (OR: 2.72; 95% CI: 1.73-4.29; P < 0.001) and an ASA-PS score ≥3 (1.64; 1.08-2.50; P = 0.021) were independent risk factors for incisional SSI in patients undergoing gastroenterological surgery during winter.

CONCLUSION

Seasonality exists in the incisional SSI incidence following general and gastroenterological surgeries. Recognizing these trends may help enhance preventive strategies, highlighting the elevated risk in summer for general surgery and in winter for gastroenterological surgery.

Influence of environmental temperature and heatwaves on surgical site infection after hip and knee arthroplasty: a nationwide study

BACKGROUND

Previous studies reported higher incidence of surgical site infection (SSI) after procedures performed in summer or with high temperatures. However, no study used detailed climate data to assess this risk after hip and knee arthroplasty, and no study specifically investigated the role of heatwaves.

AIM

To assess the impact of higher environmental temperatures and heatwaves on SSI rates after hip and knee arthroplasty.

METHODS

Data on hip and knee arthroplasty procedures performed between 01/2013 - 09/2019 in hospitals participating in the Swiss SSI surveillance were linked to climate data extracted from weather stations located in their vicinity. The association between temperature, heatwaves and SSI was studied using mixed effects logistic regression models fitted at the patient level. Poisson mixed models were fitted for both calendar year and month of the year to investigate the SSI incidence trajectory over time.

RESULTS

We included 116,981 procedures performed in 122 hospitals. Significantly higher SSI rates were observed for procedures performed in the summertime (incidence rate ratio 1.39, 95% CI [1.20-1.60], p<0.001; reference: autumn) or in calendar months in which the mean temperature was above 20°C (reference 05-10°C; odds ratio 1.59, 95% CI [1.27, 1.98] p<0.001). We observed a slight but non-significant increase in the rate of SSI during heatwaves (1.44% versus 1.01%, p=0.2).

CONCLUSION

SSI rates after hip and knee replacement appear to increase with higher environmental temperature. To establish if, and to what extent, heatwaves increase the risk of SSI, studies involving geographical areas with larger variability in temperature are needed.

The Temporality of Deep Surgical Site Infection Rates Following Spinal Laminectomy and Fusion

BACKGROUND

Deep surgical site infections (dSSI) following spinal laminectomy and fusion are serious complications associated with poor patient outcomes. The objective of this study is to investigate the monthly and seasonal variability of dSSI rates following common spinal surgeries to investigate the "July effect," which refers to the alleged increase in adverse health outcomes due to new hospital trainees at the beginning of the academic year.

METHODS

We performed a retrospective analysis of patients who had a dSSI following laminectomy (without fusion) or spinal fusion (with or without laminectomy) at a single large urban academic medical center between January 2009 and August 2018. The change in dSSI rate over the entire study period was calculated. The monthly and seasonal variability of dSSI were assessed using a Poisson regression model to assess for the presence of the July effect.

RESULTS

A total of 7931 laminectomies and 14,637 spinal fusions were reviewed. The average dSSI rates following laminectomy and spinal fusion were 0.46 (SD, 0.47) and 1.26 (SD, 0.86) per 100 patients, respectively. The rate of dSSI following spinal fusion significantly decreased over the study period (rate ratio [RR] = 0.89, 95% CI 0.84-0.94, P < 0.01). With summer as the reference season, there were significantly lower dSSI rates following spinal fusions performed in the fall (RR = 0.62, 95% CI 0.39-0.98, P = 0.04 ). With July as the reference month, there was a significantly higher dSSI rate in April following spinal fusions.

CONCLUSION

The overall decrease in dSSI rate over the study period is consistent with previous reports. The monthly analysis revealed no significant differences in either procedure, calling into question the July effect.

CLINICAL RELEVANCE

This study is relevant to practicing spinal surgeons and can inform surgeons about seasonal data regarding dSSIs.

LEVEL OF EVIDENCE: 3

Risk factors associated with surgical site infections following joint replacement surgery: a narrative review

Background

Surgical site infection following joint replacement surgery is still a significant complication, resulting in repeated surgery, prolonged antibiotic therapy, extended postoperative hospital stay, periprosthetic joint infection, and increased morbidity and mortality. This review discusses the risk factors associated with surgical site infection.

Related risk factors

The patient-related factors include sex, age, body mass index (BMI), obesity, nutritional status, comorbidities, primary diagnosis, living habits, and scores of the American Society of Anesthesiologists physical status classification system, etc. Surgery-related factors involve preoperative skin preparation, prolonged duration of surgery, one-stage bilateral joint replacement surgery, blood loss, glove changes, anti-microbial prophylaxis, topical anti-bacterial preparations, wound management, postoperative hematoma, etc. Those risk factors are detailed in the review.

Conclusion

Preventive measures must be taken from multiple perspectives to reduce the incidence of surgical site infection after joint replacement surgery.

Association of Warmer Weather and Infectious Complications Following Transrectal Ultrasound-Guided Prostate Biopsy

The seasonal and meteorological factors in predicting infections after urological interventions have not been systematically evaluated. This study aimed to determine the seasonality and the effects of the weather on the risk and severity of infectious complications (IC) after a transrectal ultrasound-guided prostate biopsy (TRUS-Bx). Using retrospectively collected data at the tertiary care hospital in Taiwan, we investigated the seasonal and meteorological differences in IC after TRUS-Bx. The IC included urinary tract infection (UTI), sepsis, and a positive culture finding (PCF). The severity was assessed on the basis of the Common Terminology Criteria for Adverse Events grading system. The prevalences of the infectious complications (UTI, sepsis, PCF and grade ≥ 3 IC) were significantly higher in the summer than in the winter. Monthly temperature and average humidity were significant factors for IC. After adjusting the demographic factors, multivariate regression revealed that UTI, sepsis, PCF, and grade ≥ 3 IC increased by 12.1%, 16.2%, 21.3%, and 18.6% for every 1 °C increase in the monthly average temperature, respectively (UTI: p = 0.010; sepsis: p = 0.046; PCF: p = 0.037; grade ≥ 3 IC: p = 0.021). In conclusion, the development and severity of IC after TRUS-Bx had significant seasonality. These were dose-dependently associated with warmer weather. Infectious signs after TRUS-Bx should be monitored more closely and actively during warm weather.

Similar infection rates in a new wound closure method following knee arthroplasty

Surgical site infections, defined as acute wound infections requiring surgical intervention within 90 days post-surgery, were retrospectively compared between a novel, zipper-like closure method (ZM) and staples in 682 patients (904 knees) and 772 patients (971 knees), respectively. The incidence of deep infections was 0.6% for staples and 0.2% for ZM (p = 0.169) and superficial infections was 0.1% for staples and 0.0% for ZM (p = 0.518). With no difference in wound complications, the ZM may be preferred since the two-week post-operative clinic visit required for wound check and staple removal was eliminated, thereby, decreasing clinic volume.

Warm Weather and Surgical Site Infections: A Meta-analysis

Seasonal variability, in terms of warm weather, has been demonstrated to be a significant risk factor for surgical site infections (SSIs). However, this remains an underexposed risk factor for SSIs, and many clinicians are not aware of this. Therefore, a systematic review and meta-analysis has been conducted to investigate and quantify this matter.

METHODS

Articles were searched in Embase, Medline Ovid, Web of Science, Cochrane Central, and Google Scholar, and data were extracted from relevant studies. Meta-analysis used random effects models to estimate and compare the pooled odds ratios (OR) and corresponding confidence intervals (CIs) of surgery performed during the warmest period of the year and the colder period of the year.

RESULTS

The systematic review included 20 studies (58,599,475 patients), of which 14 studies (58,441,420 patients) were included for meta-analysis. Various types of surgical procedures across different geographic regions were included. The warmest period of the year was associated with a statistically significant increase in the risk of SSIs (OR 1.39, 95%CI: [1.34-1.45], P < 0.0001). Selection of specific types of surgical procedures (eg, orthopedic or spinal surgery) significantly altered this increased risk.

CONCLUSIONS

The current meta-analysis showed that warm weather seasons are associated with a statistically significant risk increasement of 39% in developing SSIs. This significant risk factor might aid clinicians in preoperative patient information, possible surgical planning adjustment for high risk patients, and potentially specific antibiotic treatments during the warmer weather seasons that could result in decrease of SSIs.

Incidence of Surgical Site Infections in Multicenter Study-Implications for Surveillance Practice and Organization

Introduction: WHO core components of healthcare-associated infections (HAIs) prevention and control include their surveillance system. In Poland, there are no widespread multi-center infection surveillance networks based on continuous, targeted, active methodology. One of the most important form of HAIs are surgical site infections (SSIs). The aim of this study was to analyze the incidence of SSIs, in the context of seasonal differentiation. Seasonal differentiation could be connected with weather conditions, but it also can be affected by personnel absence due to holidays and furlough. The second aspect may influence organization of work and increased absenteeism may contribute to lowering the quality of patient care. Healthcare associated infections are the phenomenon which can be especially affected by such factors. Methods: The data used originate from the targeted, active surveillance reports obtained from the six years period, based on the ECDC recommendations. Results: Highest incidence rates of SSIs were found after operations performed in June and August, equal to 1.8% and 1.5% respectively and the lowest in October was 0.8%. These differences were statistically significant: for June incidence: OR 1.6, 95% CI 1.03–2.5, p = 0.015. Another approach showed a significant difference between the level of incidence in the period from November to January together with from June to August (1.35%), comparing to the rest of the year (1.05%). Also the rates of enterococcal and Enterobacterales infections were significantly higher for the period comprising months from November till January and from June to August. In Poland these are periods of increased number of absences associated with summer, national and religious holidays. Conclusions: Our results show that the short-term surveillance data limited to several days or months are not sufficient to obtain a valuable description of the epidemiological situation due to HAI. Efforts should be undertaken in order to implement wide net of hospital acquired infections, including SSI on the country level.

Seasonal impact on surgical site infections and wound healing disturbance in carpal tunnel surgery: A retrospective cohort study

Carpal tunnel syndrome is the most common entrapment syndrome of a peripheral nerve. The gold standard treatment is open carpal tunnel release which has a high success rate, a low complication rate, and predictable postoperative results. However, it has not been analysed yet if there is a seasonal influence on complications for carpal tunnel release, a highly elective procedure. In this retrospective study, we determine whether there is a seasonal impact on surgical site infections (SSI) and wound healing disorders (WHD) in primary carpal tunnel syndrome surgery. Between 2014 and 2018, we have assessed 1385 patients (65% female, 35% male) at a mean age of 61.9 (SD 15.3) years, which underwent open carpal tunnel release because of primary carpal tunnel syndrome. The seasonal data such as the warm season (defined as the period from 1st of June until 15th of September), the average daily and monthly temperature, and the average relative humidity were analysed. Patient demographics were examined including body mass index, alcohol and nicotine abuse, the use of anticoagulants and antiplatelet drugs as well as comorbidities. These data were correlated regarding their influence to the rate of surgical site infections and wound healing disorders in our study collective. A postoperative SSI rate of 2.4% and a WHD rate of 7% were detected. Our data confirms the warm season, the average monthly temperature, and male sex as risk factors for increasing rates of WHDs. Serious SSIs with subsequent revision surgery could be correlated with higher age and higher relative humidity. However there is no seasonal impact on SSIs. We therefore advise considering the timing of this elective surgery with scheduling older male patients preferably during the cold season to prevent postoperative WHDs.

Revision for periprosthetic joint infection rate stratified by seasonality of operation in a national population of total and unicompartmental knee arthroplasty patients: a register-based analysis

Aim: The aim of this study was to investigate whether the revision rate for periprosthetic joint infection (PJI) depends on the season of the primary procedure using a national population of knee arthroplasty (KA) patients. Seasonal variation of some surgical procedures has been observed to impact subsequent infection risks, with a higher risk of revision for surgeries performed during summer, but an analysis of PJI rates based on a national arthroplasty register has yet to be completed. We hypothesized that an increased risk of revision due to PJI could be demonstrated in a national population when primary surgery was performed during the summer. Methods: The Danish Knee Arthroplasty Registry (DKR) was used to determine the risk of revision due to PJI within 2 years after primary surgery. All primary KA procedures between 1 January 1997 and 31 December 2014 and revisions until 31 December 2016 were identified. Smoothing spline regression was used to identify possible seasonal pattern effects of the primary procedure on revision risk, and logistic regression was used to calculate risk of infection differences between seasons. Results: A total number of 124 809 primary procedures was registered in the study period. After excluding duplicates and matching primary procedures with the first revisions within 2 years after the primary procedure, 3391 were identified. Of these, 348 cases were recorded with an indication of deep infection requiring revision. Spline regression analyses did not demonstrate any clear seasonal pattern of the primary procedure regarding the risk of revision for infection or any other cause. Logistic regression found a decreased risk of revision for infection when the primary procedure was performed during the summer in the years 1997 to 2005, no influence on the risk of revision for infection in 2005 to 2012, and an increased risk of revision for infection following summer procedures during the years 2013 to 2014. Conclusion: It was not possible to demonstrate a consistent seasonal variation of the risk of revision for PJI following primary KA. This is most likely because the underlying etiologies for PJI are not subject to seasonal variation.

Climate change and antibiotic resistance: a deadly combination

Climate change is driven primarily by humanity's use of fossil fuels and the resultant greenhouse gases from their combustion. The effects of climate change on human health are myriad and becomingly increasingly severe as the pace of climate change accelerates. One relatively underreported intersection between health and climate change is that of infections, particularly antibiotic-resistant infections. In this perspective review, the aspects of climate change that have already, will, and could possibly impact the proliferation and dissemination of antibiotic resistance are discussed.

Patient-Related Risk Factors for Unplanned 30-Day Hospital Readmission Following Primary and Revision Total Knee Arthroplasty: A Systematic Review and Meta-Analysis

Total knee arthroplasty (TKA) is a highly effective procedure for advanced osteoarthritis of the knee. Thirty-day hospital readmission is an adverse outcome related to complications, which can be mitigated by identifying associated risk factors. We aimed to identify patient-related characteristics associated with unplanned 30-day readmission following TKA, and to determine the effect size of the association between these risk factors and unplanned 30-day readmission. We searched MEDLINE and EMBASE from inception to 8 September 2020 for English language articles. Reference lists of included articles were searched for additional literature. Patients of interest were TKA recipients (primary and revision) compared for 30-day readmission to any institution, due to any cause, based on patient risk factors; case series were excluded. Two reviewers independently extracted data and carried out critical appraisal. In-hospital complications during the index admission were the strongest risk factors for 30-day readmission in both primary and revision TKA patients, suggesting discharge planning to include closer post-discharge monitoring to prevent avoidable readmission may be warranted. Further research could determine whether closer monitoring post-discharge would prevent unplanned but avoidable readmissions. Increased comorbidity burden correlated with increased risk, as did specific comorbidities. Body mass index was not strongly correlated with readmission risk. Demographic risk factors included low socioeconomic status, but the impact of age on readmission risk was less clear. These risk factors can also be included in predictive models for 30-day readmission in TKA patients to identify high-risk patients as part of risk reduction programs.

Unicompartmental knee arthroplasty is associated with lower proportions of surgical site infection compared with total knee arthroplasty: A retrospective nationwide database study

BACKGROUND

This study aimed to clarify the association between types of knee arthroplasty (KA) (total knee arthroplasty (TKA) or unicompatmental knee arthroplasty (UKA)) and surgical site infection (SSI) with adjustment for various factors, using a Japanese national database.

METHODS

Data on 181,608 patients who underwent unilateral primary KA for osteoarthritis from 2010 to 2017 were obtained from the Japanese Diagnosis Procedure Combination database. SSI was identified based on International Classification of Diseases 10th Revision codes. Deep SSI (i.e. periprosthetic joint infection (PJI)) was identified as SSI treated with surgical procedures. Multivariable logistic regression analyses for SSI and PJI were performed, in which dependent variables included types of KA, patient backgrounds (sex, age, body mass index (BMI), smoking status, comorbidities), and seasonality.

RESULTS

Eight percent of analyzed patients underwent UKA, while 92% underwent TKA. The proportions of SSI and PJI after UKA were 0.9% and 0.3%, respectively, both of which were lower than those after TKA (1.9% and 0.6%) (P < 0.001). Multivariable analyses showed lower proportions of SSI for UKA (adjusted odds ratio, 0.47; 95% confidence interval, 0.37-0.60; P < 0.001) and PJI (adjusted odds ratio, 0.47; 95% confidence interval, 0.34-0.65; P < 0.001) than TKA. Other factors associated with both SSI and PJI included male sex, BMI >30 kg/m², renal dysfunction and summer season.

CONCLUSION

UKA was associated with lower proportions of SSI and PJI than TKA. Surgeons should carefully consider the indication of UKA before performing TKA, especially in patients with knee unicompartmental osteoarthritis who are at a high risk for SSI or PJI.

Seasonal patterns of incidence, demographic factors and microbiological profiles of infectious keratitis: the Nottingham Infectious Keratitis Study

PURPOSE

The purpose of this study is to examine the seasonal patterns of incidence, demographic factors and microbiological profiles of infectious keratitis (IK) in Nottingham, UK.

METHODS

A retrospective study of all patients who were diagnosed with IK and underwent corneal scraping during 2008-2019 at a UK tertiary referral centre. Seasonal patterns of incidence (in per 100,000 population-year), demographic factors, culture positivity rate and microbiological profiles of IK were analysed.

RESULTS

A total of 1272 IK cases were included. The overall incidence of IK was highest during summer (37.7, 95% confidence interval (CI): 31.3-44.1), followed by autumn (36.7, 95% CI: 31.0-42.4), winter (36.4, 95% CI: 32.1-40.8) and spring (30.6, 95% CI: 26.8-34.3), though not statistically significant (p = 0.14). The incidence of IK during summer increased significantly over the 12 years of study (r = 0.58, p = 0.049), but the incidence of IK in other seasons remained relatively stable throughout the study period. Significant seasonal variations were observed in patients' age (younger age in summer) and causative organisms, including Pseudomonas aeruginosa (32.9% in summer vs. 14.8% in winter; p < 0.001) and gram-positive bacilli (16.1% in summer vs. 4.7% in winter; p = 0.014).

CONCLUSION

The incidence of IK in Nottingham was similar among four seasons. No temporal trend in the annual incidence of IK was observed, as reported previously, but there was a significant yearly increase in the incidence of IK during summer in Nottingham over the past decade. The association of younger age, P. aeruginosa and gram-positive bacilli infection with summer was likely attributed to contact lens wear, increased outdoor/water activity and warmer temperature conducive for microbial growth.

Healthcare resources attributable to methicillin-resistant Staphylococcus aureus orthopedic surgical site infections

The number of orthopedic surgeries is increasing as populations steadily age, but surgical site infection (SSI) rates remain relatively consistent. This study aimed to quantify the healthcare resources attributable to methicillin-resistant Staphylococcus aureus (MRSA) SSIs in orthopedic surgical patients. The analysis was conducted using a national claims database comprising data from almost all Japanese residents. We examined patients who underwent any of the following surgeries between April 2012 and March 2018: amputation (AMP), spinal fusion (FUSN), open reduction of fracture (FX), hip prosthesis (HPRO), knee prosthesis (KPRO), and laminectomy (LAM). Propensity score matching was performed to identify non-SSI control patients, and generalized estimating equations were used to estimate the differences in outcomes between the case and control groups. The numbers of MRSA SSI cases (infection rates) ranged from 64 (0.03%) to 1,152 (2.33%). MRSA SSI-attributable increases in healthcare expenditure ranged from $11,630 ($21,151 vs. $9,521) for LAM to $35,693 ($50,122 vs. $14,429) for FX, and increases in hospital stay ranged from 40.6 days (59.2 vs. 18.6) for LAM to 89.5 days (122.0 vs. 32.5) for FX. In conclusion, MRSA SSIs contribute to substantial increases in healthcare resource utilization, emphasizing the need to implement effective infection prevention measures for orthopedic surgeries.

The Association of Climatic Factors with Rates of Surgical Site Infections: 17 Years' Data From Hospital Infection Surveillance

BACKGROUND

Surgical site infections (SSI) are among the most common healthcare- associated infections. The aim of our explorative study was to determine how selected climatic factors are associated with SSI rates.

METHODS

SSI rates were calculated for operative procedures included in the surgi- cal site infection surveillance component (OP-KISS) of the German Nosocomial Infection Surveillance System (Krankenhaus-Infektions-Surveillance-System, KISS) during the years from 2000 to 2016. The surgeries were associated with department-related and patient-related data. Data of the German Meteorological Service (Deutscher Wetterdienst, DWD), including outdoor temperature and rainfall, were used to analyze the association between climatic factors and rates of SSI. Analyses focused on temperature which showed strong correlations with other climatic parameters. A descriptive analysis was performed, using the chi-squared test. Adjusted odds ratios (AORs) were calculated for SSI rates in relation to tem- perature, using a multivariable logistic regression model.

RESULTS

For the altogether 2 004 793 included operative procedures, 32 118 SSIs were documented. Temperatures ≥ 20 °C were associated with a significantly higher occurrence of SSI compared to temperatures <5 °C (AOR: 1.13; 95% confi- dence intervals [1.06; 1.20]). This increase was found for gram-positive pathogens (AOR: 1.13 [1.03; 1.23]) and, even more pronounced, for gram-negative pathogens (AOR: 1.20 [1.07; 1.35]). The association was strongest for superficial SSI caused by gram-negative pathogens (AOR: 1.38 [1.16; 1.64]).

CONCLUSION

An association between climatic factors and SSI rates was demon- strated. The predicted rise in global temperatures by up to 4 °C by the end of this century compared to preindustrial levels may increase the likelihood of SSI and should be taken into consideration in future preventive strategies.

Seasonal influence on postoperative hip fracture complications: Retrospective cohort of more than 1000 patients from a tertiary-care university hospital

Background

Hip fractures account for one of the most debilitating conditions affecting the general population amongst the developed and developing nations. Investigators aimed to study the influence of the ongoing season i.e. whether patients operated upon in summer or winter, on post-operative complications occurring within 30 days of surgical procedure for hip fractures at a tertiary care hospital and level 1 trauma center.

Materials and methods

Investigators conducted a non-funded, non-commercialized retrospective cohort of 1045 patients with hip fractures managed surgically. Primary exposure was surgical procedures undertaken during the summer months (April–September). Our primary outcome was determining post-operative complication rates from January 2010 to December 2018 and evaluating impact of the season through univariate and multivariable regression analyses using Cox Proportional Hazard Algorithm with STATA V15. The work has been reported in line with the STROCSS criteria.

Results

Age, ASA status, type of procedure, mechanism of injury and Charlson Comorbidity Index (CCI) were identified as significant associated factors with postoperative complications after hip fracture surgery. Although overall results revealed a rising rate of complications during the summer season with a relative risk (RR; 95% CI) of 1.1(0.89–1.32), univariate and multivariable analysis did not show any significant correlations.

Conclusions

The results of this study did not demonstrate a significant seasonal variability in the rate of postoperative complications for hip fracture patients operated upon during the hot months of summer. More research is required to analyze postoperative complications in order to optimize patients’ outcomes.

•

The number of hip fractures has been observed to double as the population ages.

•

Surgical management is the gold standard and most effective management option.

•

Operating patients during summer is postulated to carry higher risk of postoperative complications.

•

However, this higher risk was statistically insignificant in the current study.

Summer, sun and sepsis-The influence of outside temperature on nosocomial bloodstream infections: A cohort study and review of the literature

BACKGROUND

The incidence of many infections is seasonal e.g. surgical site infections, urinary tract infection and bloodstream infections. We questioned whether there is seasonal variation even in climate-controlled hospitalized patients, and analyzed the influence of climate parameters on nosocomial bloodstream infections.

METHODS AND FINDINGS

The retrospective cohort study is based on two databases: The German national surveillance system for nosocomial infections in intensive care units (ICU-KISS) from 2001 to 2015 and aggregated monthly climate data. Primary bloodstream infection (PBSI) is defined as a positive blood culture with one (or more) pathogen(s) which are not related to an infection on another site and which were not present at admission. Monthly infection data were matched with postal code, calendar month and corresponding monthly climate and weather data. All analyses were exploratory in nature. 1,196 ICUs reported data on PBSI to KISS. The ICUs were located in 779 hospitals and in 728 different postal codes in Germany. The majority of the 19,194 PBSI were caused by gram-positive bacteria. In total, the incidence density of BSI was 17% (IRR 1.168, 95%CI 1.076-1.268) higher in months with high temperatures (≥20°C) compared to months with low temperatures (<5°C). The effect was most prominent for gram-negatives; more than one third (38%) higher followed by gram-positives with 13%. Fungi reached their highest IRR at moderately warm temperatures between 15-20°C. At such temperatures fungi showed an increase of 33% compared to temperatures below 5°C. PBSI spiked in summer with a peak in July and August. PBSI differed by pathogen: The majority of bacteria increased with rising temperatures. Enterococci showed no seasonality. S. pneumoniae reached a peak in winter time. The association of the occurrence of PBSI and temperatures ≥20°C was stronger when the mean monthly temperature in the month prior to the occurrence of BSI was considered instead of the temperature in the month of the occurrence of BSI. High average temperatures ≥20°C increased the risk of the development of a PBSI by 16% compared with low temperatures <5°C.

CONCLUSIONS

Most nosocomial infections are endogenous in nature; the microbiome plays a crucial role in host health. If gut and skin microbiome varies with season, environmental parameters will contribute to the observed incidence patterns. Similarly, the impact of global warming on both local weather patterns and extreme weather events may influence the acquisition of pathogens. A better understanding of the etiology of these infections is needed to provide guidance for future infection control strategies.

Does a "July Effect" Exist for Fellowship Training in Total Hip and Knee Arthroplasty?

BACKGROUND

The hypothetical association between health-care errors and the transition of the medical academic year has been termed the "July effect." Data supporting its existence are conflicting, particularly in orthopedic surgery, and prior studies have inappropriately grouped fellows with resident trainees. No studies to date have examined whether a training initiation effect exists among surgical fellows in adult reconstructive orthopedics.

METHODS

This is a level IV retrospective cohort study reviewing 15,650 primary hip and knee arthroplasties performed from 2006 to 2016 at a single institution. Forty arthroplasty fellows were trained during this 10-year period. Primary outcome measures included intraoperative complications, additional procedures, revisions, and nonoperative complications within 90 days of surgery. These complication rates were analyzed by quarter of academic year and by temporal progression through three-month fellowship rotations.

RESULTS

There were no differences in intraoperative complication, revision, or nonoperative complication rates between any academic quarter. There was a single statistically lower rate of additional procedures in the third quarter (1.2%) than in the fourth quarter (1.8%, P = .04). The most common complication in this subset was wound dehiscence for patients undergoing hip arthroplasty and stiffness for patients undergoing knee arthroplasty. There was no difference in complication rates during the first, second, or third month as fellows progressed through a single rotation.

CONCLUSION

This study does not support the existence of a training-initiation effect among fellows in adult hip and knee reconstruction. Graduated autonomy can be safely employed in a fellowship program without negatively impacting patient outcomes, ensuring the continued high-caliber training of future surgeons.

The Relationship Between Medicaid Coverage and Outcomes Following Total Knee Arthroplasty: A Systematic Review

BACKGROUND

Access to elective total knee arthroplasty is important in the treatment of end-stage arthritis, and numerous initiatives, including Medicaid expansion, have sought to improve patients' ability to undergo this procedure. However, despite this, the role of Medicaid insurance in patient outcomes remains unclear. The purpose of this study was to perform a systematic review of the literature to explore the relationship between preoperative Medicaid insurance status and outcomes following primary total knee arthroplasty.

METHODS

A systematic review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines to identify studies examining outcomes in patients who had Medicaid and were undergoing total knee arthroplasty. Studies including complex revision operations or less common indications for total knee arthroplasty were excluded. Data on insurance status, postoperative complications, length of stay, readmissions, and subsequent revision surgical procedures were collected for each article.

RESULTS

A total of 13 studies showing 6.18 million patients undergoing total knee arthroplasty were included in the qualitative synthesis. Seven analyses described an important association between Medicaid coverage and short-term readmissions, and 2 analyses showed a relationship between Medicaid and prolonged length of stay. However, the included studies did not describe a significant association between Medicaid and postoperative mortality or revision rates.

CONCLUSIONS

Patients with Medicaid undergoing total knee arthroplasty may be more likely to experience an increased length of stay and to be readmitted postoperatively. The unique factors associated with these patients may help to inform customized perioperative surveillance and optimization to improve outcomes in this group.

LEVEL OF EVIDENCE

Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Effectiveness of Iodophor vs Chlorhexidine Solutions for Surgical Site Infections and Unplanned Reoperations for Patients Who Underwent Fracture Repair: The PREP-IT Master Protocol

IMPORTANCE

The risk of developing a surgical site infection after extremity fracture repair is nearly 5 times greater than in most elective orthopedic surgical procedures. For all surgical procedures, it is standard practice to prepare the operative site with an antiseptic solution; however, there is limited evidence to guide the choice of solution used for orthopedic fracture repair.

OBJECTIVE

To compare the effectiveness of iodophor vs chlorhexidine solutions to reduce surgical site infections and unplanned fracture-related reoperations for patients who underwent fracture repair.

DESIGN, SETTING, AND PARTICIPANTS

The PREP-IT (Program of Randomized Trials to Evaluate Pre-operative Antiseptic Skin Solutions in Orthopaedic Trauma) master protocol will be followed to conduct 2 multicenter pragmatic cluster randomized crossover trials, Aqueous-PREP (Pragmatic Randomized Trial Evaluating Pre-Operative Aqueous Antiseptic Skin Solution in Open Fractures) and PREPARE (Pragmatic Randomized Trial Evaluating Pre-Operative Alcohol Skin Solutions in Fractured Extremities). The Aqueous-PREP trial will compare 4% aqueous chlorhexidine vs 10% povidone-iodine for patients with open extremity fractures. The PREPARE trial will compare 2% chlorhexidine in 70% isopropyl alcohol vs 0.7% iodine povacrylex in 74% isopropyl alcohol for patients with open extremity fractures and patients with closed lower extremity or pelvic fractures. Both trials will share key aspects of study design and trial infrastructure. The studies will follow a pragmatic cluster randomized crossover design with alternating treatment periods of approximately 2 months. The primary outcome will be surgical site infection and the secondary outcome will be unplanned fracture-related reoperations within 12 months. The Aqueous-PREP trial will enroll a minimum of 1540 patients with open extremity fractures from at least 12 hospitals; PREPARE will enroll a minimum of 1540 patients with open extremity fractures and 6280 patients with closed lower extremity and pelvic fractures from at least 18 hospitals. The primary analyses will adhere to the intention-to-treat principle and account for potential between-cluster and between-period variability. The patient-centered design, implementation, and dissemination of results are guided by a multidisciplinary team that includes 3 patients and other relevant stakeholders.

DISCUSSION

The PREP-IT master protocol increases efficiency through shared trial infrastructure and study design components. Because prophylactic skin antisepsis is used prior to all surgical procedures and the application, cost, and availability of all study solutions are similar, the results of the PREP-IT trials are poised to inform clinical guidelines and bring about an immediate change in clinical practice.

TRIAL REGISTRATION

ClinicalTrials.gov Identifiers: NCT03385304 and NCT03523962.

Seasonal effect on the incidence of post-operative wound complications after trauma-related surgery of the foot, ankle and lower leg

INTRODUCTION

Post-operative wound complications remain among the most common complications of orthopedic (trauma) surgery. Recently, studies have suggested environmental factors such as season to be of influence on wound complications. Patients operated in summer are reported to have more wound complications, compared to other seasons. The aim of this study was to identify if "seasonality" was a significant predictor for wound complications in this cohort of trauma-related foot/ankle procedures.

MATERIALS AND METHODS

This retrospective cohort study included all patients undergoing trauma-related surgery (e.g. fracture fixation, arthrodesis, implant removal) of the foot, ankle or lower leg. Procedures were performed at a Level 1 Trauma Center between September 2015 until March 2019. Potential risk factors/confounders were identified using univariate analysis. Procedures were divided into two groups: (1) performed in summer (June, July or August), (2) other seasons (September-May). The number of surgical wound complications (FRIs, SSIs or wound dehiscence) was compared between the two groups, corrected for confounders, using multivariate regression.

RESULTS

A total of 599 procedures were included, mostly performed in the hindfoot (47.6%). Patients were on average 46 years old, and mostly male (60.8%). The total number of wound complications was 43 (7.2%). Age, alcohol abuse, open fracture and no tourniquet use were independent predicting factors. No difference in wound complications was found between summer and other seasons, neither in univariate analysis [4 (3.2%) vs 39 (8.2%), p = 0.086] nor when corrected for predicting factors as confounders (p = 0.096).

CONCLUSIONS

No seasonality could be identified in the rate of wound complications after trauma surgery of the lower leg, ankle and foot in this cohort. This lack of effect might result from the temperate climate of this cohort. Larger temperature and precipitation differences may influence wound complications to a larger extent. However, previous studies suggesting seasonality in wound complications might also be based on coincidence.

Medicaid insurance status predicts postoperative mortality after total knee arthroplasty in state inpatient databases

Aim: Medicaid versus private primary insurance status may predict in-hospital mortality and morbidity after total knee arthroplasty (TKA). Materials & methods: Regression models were used to test our hypothesis in patients in the State Inpatient Database (SID) from five states who underwent primary TKA from January 2007 to December 2014. Results: Medicaid patients had greater odds of in-hospital mortality (odds ratio [OR]: 1.73; 95% CI: 1.01-2.95), greater odds of any postoperative complications (OR: 1.25; 95% CI: 1.18-1.33), experience longer lengths of stay (OR: 1.09; 95% CI: 1.08-1.10) and higher total charges (OR: 1.03; 95% CI: 1.02-1.04). Conclusion: Medicaid insurance status is associated with higher in-hospital mortality and morbidity in patients after TKA compared with private insurance.

Association between higher ambient temperature and orthopaedic infection rates: a systematic review and meta-analysis

INTRODUCTION

Many infectious diseases display seasonal variation corresponding with particular conditions. In orthopaedics a growing body of evidence has identified surges in post-operative infection rates during higher temperature periods. The aim of this research was to collate and synthesize the current literature on this topic.

METHODS

A systematic review and meta-analysis was performed using five databases (PubMed, Embase, CINAHL, Web of Science and Central (Cochrane)). Study quality was assessed using the Grading of Recommendations Assessment, Development and Evaluation method. Odds ratios (ORs) were calculated from monthly infection rates and a pooled OR was generated using the DerSimonian and Lairds method. A protocol for this review was registered with the National Institute for Health Research International Prospective Register of Systematic Reviews (CRD42017081871).

RESULTS

Eighteen studies analysing over 19 000 cases of orthopaedic related infection met inclusion criteria. Data on 6620 cases and 9035 controls from 12 studies were included for meta-analysis. The pooled OR indicated an overall increased odds of post-operative infection for patients undergoing orthopaedic procedures during warmer periods of the year (pooled OR 1.16, 95% confidence interval 1.04-1.30).

CONCLUSION

A small but significantly increased odds of post-operative infection may exist for orthopaedic patients who undergo procedures during higher temperature periods. It is hypothesized that this effect is geographically dependent and confounded by meteorological factors, local cultural variables and hospital staffing cycles.

Humidity a potential risk factor for prosthetic joint infection in a tropical Australian hospital

BACKGROUND

Many pathogens of importance, including the staphylococcal species of concern in orthopaedics, demonstrate seasonal variations influenced by environmental factors. The aim of this study was to investigate the role of humidity as a risk factor for deep prosthetic joint infection following total knee arthroplasty (TKA) in a tropical Australian hospital.

METHODS

A retrospective cohort study of all TKAs performed over a 13-year period was conducted at the author's institution. Univariate analysis was used to individually assess for a range of risk factors including humidity >60% and apparent temperature >30°C (86°F). Odds ratios (ORs) were reported. P-values <0.25 were considered as potentially important risk factors and P-values <0.05 were considered statistically significant.

RESULTS

A total of 1058 primary TKAs were performed with a deep prosthetic joint infection incidence of 2.7%. Four potential risk factors were identified with P-values <0.25: (i) humidity >60% (OR 1.4; 95% confidence interval (CI) 0.68-3.04; P = 0.221); (ii) apparent temperature >30°C (86°F) (OR 2.4; 95% CI 0.56-10.1; P = 0.174); (iii) male gender (OR 2.2; 95% CI 1.02-4.81; P = 0.057); and (iv) American Society of Anesthesiologists score of III or IV (OR 2.1; 95% CI 1.00-4.49; P = 0.064).

CONCLUSION

Humidity and apparent temperature may be potentially important risk factors for infection following TKA.

Surgical masks as source of bacterial contamination during operative procedures

Background

Surgical masks (SMs) are used to reduce bacterial shedding from the mouth, nose and face. This study aimed to investigate whether SMs may be a potential source of bacterial shedding leading to an increased risk of surgical site infection.

Methods

Bacterial contamination of the SMs was tested by making an impression of the external surface of the mask on sterile culture media immediately. We investigated the difference in bacterial counts between the SMs worn by surgeons and those placed unused in the operating room (OR), and the bacterial count variation with indicated wearing time. Moreover, the difference in bacterial counts on the external surface between the first and second layers of double-layered SMs was also assessed.

Results

The bacterial count on the surface of SMs increased with extended operating times; significant difference was found between the 4- to 6-hour and 0-hour groups (p < 0.05). When we analysed the bacterial counts from the same surgeon, a significant increase was noted in the 2-hours group. Moreover, the bacterial counts were significantly higher among the surgeons than the OR. Additionally, the bacterial count of the external surface of the second mask was significantly higher than that of the first one.

Conclusions

The source of bacterial contamination in SMs was the body surface of the surgeons rather than the OR environment. Moreover, we recommend that surgeons should change the mask after each operation, especially those beyond 2 hours. Double-layered SMs or those with excellent filtration function may also be a better alternative.

The translational potential of this article

This study provides strong evidence for the identification that SMs as source of bacterial contamination during operative procedures, which should be a cause for alarm and attention in the prevention of surgical site infection in clinical practice.