Clinical Study Of Surgical Site Infection After Foot And Ankle Surgery

Foot and ankle surgery involves foot and ankle fracture as well as elective orthopedic surgery,and the risk of incision infection after foot and ankle surgery is relatively high due to the special anatomical location of the foot and ankle,bone morphological characteristics,thin soft tissue wrapping,blood supply,and bacterial colonization preference.Defining the population characteristics,combined disease characteristics,bad living habits,surgical characteristics,preoperative laboratory indicators and other factors of posto-perative incision infection has important clinical significance for better mana-gement and prevention of postoperative incision infection.Previous studies have identified multiple associated risk factors such as diabetes,smoking,obesity,timing of surgery,antibiotic prophylaxis,hypoalbuminemia,increased intraoperative temperature,use of drains,etc.,but these findings may be limited by some methodological shortcomings,such as retrospective studies,high selection of study populations,relatively small sample sizes,relatively few included covariates and confounding variables,and may therefore be biased;in addition,these findings are almost exclusively single-center studies and therefore the applicability or extrapolation of the results is low.In the past 10 years,with the continuous economic and social development of China and the improvement of people’s living standards,the demand for foot orthopedic surgery is increasing,and the base number of patients undergoing surgery is increasing,so it may continue to face the increase of infection events for a certain period of time,which will have a significant impact on the patients themselves,the medical insurance system,families and society.Therefore,the study of the incidence and risk factors of incision infection after foot and ankle surgery will have very positive practical significance and medical needs.Peri-ankle fractures are the most common clinical orthopedic injuries,most of which are intra-articular fractures and require surgical treatment,but the surgical results are affected by complications,especially the occurrence of surgical site infections,although low,but the consequences are serious and even disabling.At present,there are not many studies on peri-ankle fractures,but the results are consistent and the incidence variability is large,and the methods taken to determine the risk factors are different,and the inclusion of adjusted confounding variables and covariates is insufficient,affecting the final results and applicability.In this study,we determined the risk factors of surgical treatment of deep surgical site infection(DSSI)of peri-ankle fractures by propensity score(PSM).Elective foot and ankle surgery is an extremely important part of foot and ankle surgery,which plays a very critical role in reconstructing foot and ankle anatomy,correcting lower limb alignment and restoring walking function.However,due to the anatomical characteristics of foot and ankle(thin subcutaneous tissue,relatively poor blood supply)and the environment of forefoot and midfoot(humid),it is easy to lead to bacterial colonization and reproduction,which may cause infection after surgery,affect the surgical effect,and in severe cases,it can be disabled and significantly reduce its walking ability.At present,there are many studies on fractures around the ankle joint,but few studies on elective foot and ankle surgery.This study investigated the incidence of surgical site infection and its related risk factors after elective foot and ankle surgery by reviewing the inpatient medical records of patients.Part One Risk factors for deep infection at the incision site after Sur-gery for periankle fractures: a case control study based on propensity score matching(PSM)Objective: Periarticular ankle fractures are the most common clinical injuries in orthopedics,most of which are intra-articular fractures and require surgical treatment,but the surgical results are affected by complications,especially the occurrence of surgical site infection.Although they occur low,the consequences are serious and even disabling.At present,there are not many studies on periarticular ankle fractures,but the results are consistent,the incidence variability is large,the methods to determine the risk factors are different,and the inclusion of adjusted confounding variables and covariates is insufficient,affecting the final results and applicability.In this study,we determined the risk factors of surgical treatment of deep ankle fracture incision site infection(DSSI)by propensity score distribution ratio(PSM).Methods: First,the base number of surgically treated cases and the number of cases with deep infection of adult peri-ankle fractures were determined by consulting the inpatient medical records of patients,and the incidence of incision site infection was determined in the case group and the control group after strict inclusion and exclusion criteria,based on which the incidence of incision site infection was calculated;then,according to the six most commonly used baseline variables,namely age,gender,living area(city or population),insurance type(public fee or other),fracture site(single ankle,double ankle,and three ankles),and operation date(accurate to the day),the propensity score of patients with deep incision site infection was calculated,according to the propensity score,the nearest neighbor matching method was adopted,with a clamp value of 0.01 and no replacement,and the patients were selected from the control group as the case group for pairing,with a ratio of 1:2,and the standardized mean difference(SMD)was used to assess the balance after pairing between groups,with a SMD ≥ 0.15 index imbalance,< 0.15 as balanced between groups,and the process was completed by R software3.6.5.Conditional logistic regression analysis was performed to identify risk factors for surgical incision site infection by querying inpatient records and surgical records and laboratory reports to collect data on patients who underwent surgical treatment for fractures around the ankle joint as covariates or confounding variables.Results: After strict inclusion and exclusion criteria,a total of 2147 patients were included in this study,of whom 74 developed deep surgical incision site infection within one year after surgery,so the incidence of deep infection was 3.4%.After propensity score matching,70 deep-infected patients met the matched needs and 140 controls comprised the study cohort.Univariate analysis showed that there were no significant differences between the two groups in any surgical history(31.4% vs 15.7%,P=0.008),time from injury to surgery(continuous variable 7.3±5.4 vs 5.9±3.1,P=0.016;among categorical variables,17.1% vs 7.1% at < 4 days;47.1% vs 75.0% at 4-10 days;35.7% vs 17.9% at > 10 days;P<0.001),surgical wound classification(cleancontamination,25.7% vs 5.7%,P<0.001),smoking(30.0% vs 16.4%,P=0.023),alcohol consumption(55.7% vs 40.7%,P=0.040),red blood cell count decreased(continuous variable,4.1±0.7 vs 4.3±0.6,P=0.047;among categorical variables,35.7% vs 22.1%,P=0.036),hemoglobin concentration(124.5±22.6 vs 133.6±18.5,P=0.002;categorical variable,32.9% vs 14.3%,P=0.002),and hematocrit(continuous variable,36.8±56.8,P=0.002).P=0.002;categorical variables,62.9% vs 43.6%,P=0.008).However,no significant differences were observed in other variables.Conditional logistic regression analysis showed that operative time < 4 or > 9(versus 4-9 days,< 4,OR=5.2(95% CI,1.8-14.9);> 9,OR=2.4(95% CI,1.1-5.1)),wound(II vs I)(OR,4.4;95% CI,1.7-11.7),current smoking(OR,2.6;95% CI,1.2-5.6),high-energy mechanism of injury(OR,2.1;95% CI,1.1-4.8),and lower hematocrit(OR,1.9;95% CI,1.0-3.9)were independent risk factors for deep incisional site infection following surgery for peri-ankle fractures.Conclusions: Timely adjustment of smoking and hematocrit and surgery within a reasonable time frame to obtain optimal soft tissue conditions may provide clinical benefits for the prevention of SSI.Part Two A retrospective study on the incidence and risk factors of surgical site infection after elective foot and ankle surgeryObjective: Elective foot and ankle surgery is an important part of foot and ankle surgery,which plays a very critical role in reconstructing foot and ankle anatomy,correcting lower limb alignment,and restoring walking func-tion.However,due to the anatomical characteristics of foot and ankle(thin subcutaneous tissue,relatively poor blood supply)and the environment of forefoot and midfoot(humid),it is easy to lead to bacterial colonization and reproduction,may cause infection after surgery,affect the surgical effect,severe cases can be disabled,and significantly reduce their walking ability.At present,there are many studies on fractures around the ankle joint,but few studies on elective foot and ankle surgery.This study investigated the inci-dence of surgical site infection and its related risk factors after elective foot and ankle surgery by reviewing the inpatient medical records of patients.Methods: This study was designed as a retrospective study in which two systematically trained investigators searched the inpatient medical record system for patients from July 2015 to June 2018,and candidate inclusion criteria were adult patients undergoing elective foot and ankle surgery during this time period with complete baseline characteristic data and complete records on incisional infections on telephone follow-up within one year after surgery.According to the status of surgical site infection recorded in the postoperative medical records and the results of telephone follow-up,it was determined whether the patients had infection,and divided into deep infection and superficial infection according to the definition of infection.Considering its rarity,the two were combined as the outcome variable(infection)to facili-tate statistical analysis.After determining enrollment,two investigators revie-wed the patients’ inpatient medical records and collected data on demo-graphics,comorbidities,and perioperative parameters from progress notes,laboratory test reports,surgical reports,and outpatient follow-up registers.Differences between infected and non-infected groups were analyzed by univariate analysis,and independent associations between independent varia-bles and outcome variables were confirmed by multivariate logistic regression models.Results: A total of 1201 patients underwent 1259 elective foot and ankle surgeries,of whom 26(2.1%)developed surgical site infections,with superficial and deep infection rates of 1.3% and 0.8%,respectively.Microbial culture showed 7 cases of Pseudomonas aeruginosa,6 cases of methicillin-resistant Staphylococcus aureus(MRSA),5 cases of methicillin-susceptible Staphylococcus aureus(MSSA),2 cases of methicillin-resistant coagulasenegative staphylococci(MRCNS),2 cases of Escherichia coli,and 1 case of Proteus mirabilis.Five factors were identified as independently associated with SSI,including increased preoperative hospital stay(OR,1.21;95% CI,1.09 to1.30),allograft or bone substitute(OR,3.76;95% CI,1.51 to 5.30),increased fasting glucose levels(OR,1.17;95% CI,1.04 to 1.26),decreased ALB levels(OR,2.33;95% CI,1.19 to 3.05),and increased preoperative neutrophil counts(OR,1.72;95% CI,1.27 to 2.12).Conclusions: The incidence of surgical site infection after elective foot and ankle surgery is low,but it is relatively high in forefoot surgery and needs special attention in clinical practice.Although most risk factors are not modifiable,they contribute to infection risk assessment and stratification.