Surgical site infections (SSIs) are a leading healthcare-associated infection (HAI) and are an important cause of morbidity and mortality after surgical procedures worldwide.[1] The Centers for Disease Control and Prevention (CDC) define an SSI as an infection that happens within 30 days of surgery or within 1 year if an implant was placed during the procedure, involving the site of the surgical incision, the deep soft tissues, or the organ/space handled during surgery.[2] Orthopedic surgery is especially susceptible to SSIs due to the use of implants, prosthetic joints, and internal fixation devices that create surface areas for adhesion of bacteria and the biofilm that forms.[3] These infections can result in longer healing times, longer hospital stays, implant rejection, osteomyelitis, reoperation, healthcare expenses, and permanent disability and quality of life issues.[4] Despite having made significant advances in surgical techniques, perioperative antibiotic prophylaxis, and infection prevention strategies, SSIs remain a significant challenge in orthopedic practice.[5]

Globally, surgical site infection (SSI) is estimated to be one of the most common preventable surgical complications, with about 20% of all healthcare-associated infections (HAIs) being attributed to surgical site infection.[6] The occurrence of SSI is influenced by a complex interaction of patient-, procedure-, and hospital-related factors.[7] Advanced age, diabetes mellitus, obesity, smoking, malnutrition, anemia, immunosuppression, and other chronic co-morbidities are significant factors in postoperative infections.[8]

Likewise, extended operating times, emergency operations, open fractures, implant insertion, heavy blood loss, inadequate antibiotic treatment, and failure to follow aseptic precautions are significant risk factors for infection.[9] Microbiologically, Staphylococcus aureus, including methicillin-resistant S. aureus (MRSA), continues to be the most common pathogen, although the number of Gram-negative organisms is increasing, especially for trauma-related procedures.[10] The identification of these predictors at an early stage would be crucial to take effective preventive measures and improve surgical results.[11]

The negative effect of orthopedic SSIs is much more than just wound complications.[12] Patients with postoperative infections usually receive extended hospital stays, multiple surgical debridements, extended antibiotic treatment, implant removal or revision surgery, and intensive rehabilitation.[13]

While many studies have examined orthopedic SSI, there is significant variation in the incidence and risk factors among studies of SSI in different healthcare settings, especially in developing countries where there are limited local epidemiological data. Any variations in patient characteristics, surgical techniques, microbial flora, and infection prevention practices require individual institution evaluation to determine modifiable risk factors and to direct evidence-based intervention. Hence, the study was designed as a prospective observational study to identify the incidence, risk factors, and clinical impact of surgical site infection after orthopedic surgery in a tertiary care hospital. The results will inform the creation of relevant local evidence to help formulate successful infection prevention measures, better post-operative results, and to decrease the overall burden of SSIs in orthopedic practice.

This study was a prospective observational study that aimed to identify the prevalence, risk factors, and outcomes of surgical site infections (SSIs) in people who underwent orthopedic surgery. The study was carried out in the Orthopedic Ward and Trauma Centre, DHQ Teaching Hospital, Dera Ismail Khan, Khyber Pakhtunkhwa, Pakistan. The study was carried out for 12 months from 1st January 2024 to 31st December 2025. Sample size was determined using OpenEpi version 3.01, a single population proportion estimation. In a previous prospective study, Gul et al. found the incidence of surgical site infections was 12.5% in patients undergoing orthopedic surgery.[14] A minimum sample size of 168 patients was calculated, given an expected prevalence of 12.5%, a 95% confidence level, and a margin of error of 5%. The sampling technique was non-probability, consecutive sampling. Patients of the Orthopedic Surgery and Trauma Department who were admitted to the ward, had fulfilled the selection criteria, and had undergone orthopedic surgery during the study period were invited to participate in the study. Recruitment was carried out continuously until the required sample size was met. The study involved patients aged 18 years and older who had undergone elective surgery or emergency surgery in DHQ Teaching Hospital, Dera Ismail Khan, including orthopedic surgery involving internal fixation, external fixation, implant placement, or any orthopedic operative procedure. Patients who signed informed consent forms and agreed to attend for postoperative follow-up for 30 days were recruited. Previous surgical wound infection, chronic osteomyelitis, previous operation with an active systemic infection, pathological fracture due to malignancy, and patients who had undergone minor procedures that do not warrant an operative incision were excluded. Those who died within 48 hours from surgery unrelated to surgical site infection, were moved to another health care facility before the end of the follow-up, or were lost to follow-up were also excluded from the final analysis. Eligible participants were selected after obtaining informed consent and ethical approval from the Institutional Review Board and were asked to complete a structured, predesigned data collection proforma for baseline demographic and clinical data. Data were collected for aspects including age, gender, body mass index, smoking status, diabetes mellitus, hypertension, anemia, American Society of Anesthesiologists (ASA) physical status classification, indication for surgery, type of surgery (elective vs emergency), wound classification, duration of surgery, use of implants, administration and timing of prophylactic antibiotics, and other relevant perioperative variables.[15] Surgery was conducted according to the normal operating protocols in the hospital, with extreme care taken to follow the rules of asepsis in a careful manner. All patients were assessed for clinical signs of surgical site infection every day during their hospital stay. The size of the wound was evaluated according to the CDC diagnostic criteria for SSI by the attending orthopedic surgeon. Patients were then followed for 30 days after surgery either in the outpatient clinic or by telephone interviews. A wound swab or tissue sample was taken under sterile conditions whenever SSI was suspected and sent to the microbiology laboratory for culture and antimicrobial susceptibility testing following standard laboratory protocol. Data on the time of onset of SSI, the microorganisms identified, the need for reoperation, length of hospital stay, rehospitalization, removal of the implant, and other complications following surgery were collected. All data collected were verified daily for completeness and accuracy prior to the data being entered in the database. Data were recorded and analysed with SPSS version 26.0. Continuous variables were presented as mean ± SD. Frequencies and percentages were used to summarize categorical variables such as gender, diabetes mellitus, smoking, type of surgery, wound classification, implant type, and surgical site infection. The rate of surgical site infection was defined as the number of patients with SSI/30 days after surgery. The Chi-square test and Fisher's exact test were used to investigate associations between potential predictor variables and SSI for categorical variables and between predictor variables and SSI for continuous variables using the Independent t-test. Those variables that had a p-value <0.20 in univariate analysis were included in a multivariable binary logistic regression model to determine factors independently associated with surgical site infection. Odds ratios (ORs) were adjusted for age and other known risk factors and presented with 95% confidence intervals (CIs). A p-value < 0.05 was considered statistically significant.

A total of 168 patients who underwent orthopedic surgery were included in the study. The mean age of the participants was 43.8 ± 15.2 years, with the majority being male (66.7%). The mean body mass index was 26.1 ± 4.3 kg/m². The prevalence of diabetes mellitus, hypertension, anemia, and smoking was 22.6%, 29.2%, 18.5%, and 27.4%, respectively. Most patients were classified as ASA II (48.2%), followed by ASA I (32.7%) and ASA III (19.1%). (Table 1).

The majority of surgical procedures were emergency ones (56.0%), and 44.0% were elective surgeries. The most frequent indication for surgery was trauma and fracture fixation (61.3%). The mean operative time was 109.4 ± 36.8 minutes, and 75.0% of patients received orthopedic implants. Prophylactic antibiotics were given to 97.6% of patients, 90.5% receiving them within the recommended 60 minutes before skin incision. (Table 2).

During the 30-day postoperative follow-up, 11 patients (6.5%) developed surgical site infections. The most common type of SSI was superficial incisional (63.6%), followed by deep incisional (27.3%) and organ/space (9.1%) infections. The most common microorganism found in infected wounds was S. aureus (45.5%), followed by MRSA, E. coli, K. pneumoniae, and P. aeruginosa. (Table 3).

The mean time to SSI was 8.2 ± 3.4 days after surgery among the patients who did develop infection. The average length of stay in hospital was 14.6 ± 5.2 days. Of the infected patients, 27.3% required reoperation, 18.2% required implant removal, and 36.4% were readmitted to the hospital. In the follow-up period, the majority of patients (90.9%) improved with treatment. (Table 4).

The following factors were found to be significantly associated with the development of surgical site infection (p < 0.05) by univariate analysis: older age, obesity, diabetes mellitus, ASA III status, prolonged operative duration, and delayed administration of prophylactic antibiotics. There was no significant association between SSI and gender, smoking status, use of implants, or emergency surgery. (Table 5).

Variables that had a p-value less than 0.20 in univariate analysis proceeded to a multivariate logistic regression model. Diabetes mellitus (p = 0.032), obesity (p=0.047), anemia (p = 0.045), operative duration > 120 minutes (p =0.006), and delayed administration of the prophylactic antibiotic (p = 0.005) remained independent predictors of surgical site infection after adjustment for potential confounders. (Table 6).

Table 1. Baseline demographic and clinical characteristics of the study participants (n = 168)

Table 2. Operative and perioperative characteristics (n= 168)

Table 3. Incidence and microbiological profile of surgical site infection

Table 4. Clinical outcomes among patients with SSI (n = 11)

Table 5. Univariate analysis of predictors of surgical site infection

Table 6. Multivariable binary logistic regression for predictors of surgical site infection

In the present study, a total of 6.5% of SSI occurred following orthopedic surgery, with superficial SSI being the most common type, which accounted for almost 2/3 of all surgical site infections. This incidence is within the range reported in modern orthopedic literature, and the rates of SSI are mainly dependent on the type of procedure, the characteristics of the patients, and the hospital environment. The incidence of SSI after ORIF of distal femur fractures was determined to be 6.0% in a prospective study conducted by Chao Zhu et al., a figure similar to our results.[16] Likewise, in 2026, research on orthopedic implant surgery in Pakistan showed a similar incidence rate, highlighting the importance of trauma-related surgeries and orthopedic implants in causing an infection after surgery.[17] In our study, Staphylococcus aureus was found to be the most common pathogen recovered from wounds, followed by methicillin-resistant Staphylococcus Aureus (MRSA), Escherichia coli, Klebsiella Pneumoniae, and Pseudomonas Aeruginosa. These results corroborate earlier studies that have identified S. Aureus as the most common cause of orthopedic infections due to its tendency to attach to orthopedic implants and develop biofilms. Gram-positive Cocci were also the most common pathogens in orthopedic implant infections in all the epidemiological studies published from 2021 to 2026, and similarly, Zhu et al. reported S. Aureus to be the most prevalent microorganism in infected fracture fixation cases.[16, 18] The univariate analysis revealed that age was significantly associated with SSI. Older age has long been known to be a key factor in a decrease in immune function, less tissue perfusion, and more comorbid conditions that may all contribute to impaired wound healing. The same was seen in recent orthopedic studies, such as the multicenter study of patellar fracture done in 2025, where higher-risk patient subgroups (higher ASA score and longer hospital stay) accounted for a significant proportion of the postoperative infections.[19] In the multivariable analysis, obesity was an independently associated factor of SSI. Patients with BMI ≥ 30 kg/m² had significantly higher odds of having postoperative infection than non-obese patients. This is consistent with the recent study by Brian D. Rust et al., which showed that BMI is a better predictor of SSI than local adiposity following fixation of distal femur fracture. There have been other orthopedic studies since 2021 that found similar associations, in which obesity was associated with longer operative time, worse wound healing, and bacterial colonization.[20] Another interesting finding from the present study was that diabetes mellitus was another independent risk factor for SSI. Hyperglycemia affects the function of leukocytes, collagen synthesis, and tissue repair, all of which make people more likely to get a postoperative wound infection. Similar results have been seen in many orthopedic studies, such as the prospective study by Zhu et al., which highlighted the need for improving metabolic status before surgery.[16] Similarly, the PakSurg-1 multicenter cohort emphasized the significance of patient comorbidities and perioperative optimization as two key factors to consider in the strategies for the prevention of SSI.[21] Our study showed an independent association between anemia and SSI. Limited oxygen levels in healing tissues result in diminished collagen formation and immune response within the wounded area, making the patient susceptible to infection. While anemia itself has not been consistently studied in all orthopedic studies, some recent studies have documented that factors of poor nutrition and physiological status are significant factors for increased postoperative complications, consistent with our findings and highlighting the need to correct reversible hematological abnormalities before surgery.[16, 22] In our study, SSI-affected patients were hospitalized for longer, had more readmissions, reoperations, and implant removals, indicating the significant clinical burden of postoperative infection. These observations align with recent orthopedic and national surgical cohorts that showed that SSI significantly contributes to patient morbidity, surgical costs, and healthcare utilization. Overall, our results confirm existing evidence that proper patient optimization, antibiotic prophylaxis at the correct time, limiting surgery time when possible, and strict attention to infection control measures are critical to reducing surgical site infection and maximizing postoperative results in orthopedic surgery. Limitations There were several limitations with this research. Firstly, it was performed in a single tertiary care hospital, which may restrict the generalizability of the results to other health care settings. Second, follow-up was conducted for 30 days after surgery, as recommended by the CDC, but infections that happen later after the surgery may not have been detected. Third, the relatively low number of surgical site infection cases may have reduced the statistical power to uncover weaker associations with some potential risk factors. Fourth, because of the exclusion of other factors, like nutritional status, blood glucose levels before surgery, during surgery, and after surgery, blood loss during surgery, and surgeon-related variables, which may affect the incidence of SSI. Lastly, microbiological cultures were conducted only for clinically suspected cases of SSI, and molecular characterization of antimicrobial resistance was not conducted.

Orthopedic surgery SSI is still a significant postoperative problem associated with orthopedic surgery that leads to prolonged hospital stays, reoperation, readmission, and high health care costs. Diabetes mellitus, obesity, anemia, operative duration more than two hours, and delayed administration of prophylactic antibiotics were found to be independent predictors of SSI in the present study. Early recognition and optimization of these modifiable risk factors, in addition to careful and careful application of evidence-based infection prevention measures and timely antimicrobial prophylaxis, can significantly decrease the incidence of SSI and enhance postoperative outcomes. Larger multicenter prospective studies are recommended to confirm these results and to create comprehensive risk prediction models for orthopedic surgical patients.