During the study period, a total of 4842 patients with limb fractures underwent surgery, and 363 patients were excluded under our strict criteria, with the remaining 4479 patients included for data analysis. There were 2592 males and 1887 females, with a mean age of 51.3 years (SD, 18.7;Range, 1-104).1351 (30.2%) of limb fractures were high energy injuries, and 317 (7.1%) were open fractures.The most common fractures were in the tibia and fibula (1156,25.8%) and ulna and radius (1039, 23.2%). This was followed by femoral fractures (909,20.3%).The number of fractures of humerus, foot and patella were 554 (12.4%), 423 (9.4%) and 398 (8.9%), respectively. The average preoperative hospital stay was 6.1 days (SD, 6.5;The Range of 0-61). 1087 were operated on within 2 days, 2393 on days 3 to 7, and the remaining 999 on more than 7 days after admission. [Table 1]
Microbiology:
The microorganism most frequently isolated from infected surgical wounds was Staphylococcus aureus (S. aureus) (25.1%). This was followed by Coagulase negative Staphylococcus (CONS) (18.8%). The next were Acinetobacter baumannii (AB) (12.0%) and Pseudomonas aeruginosa (PA) (8.3%) respectively. Distribution of microorganism according to fracture site also was showed in Table 2.
Methicillin-resistant S. aureus (MRSA) prevalence was 81.3% (39 strains). The prevalence of multidrug-resistant (MDR) AB and MDR PA were 78.3% (19 strains) and 6.3% (1 strains) respectively. Klebsiella pneumoniae (KP) Producing ESBL prevalence was 36.4% (4 strains).
In univariate analysis, 7 variables were found to be significantly associated with gram-positive or gram-negative bacterial infection. (P<0.05) They included Vascular injury at the fracture site, fracture type, ASA index, preoperative stay, WBC, NEUT, blood glucose and TP. 13 variables were found to be approximately associated with gram-positive or gram-negative bacterial infection., including age, BMI, cerebrovascular disease, fracture site, nerve injury at the fracture site, skin contusin at the fracture site, postoperative drainage use, LYM, HGB, ALB, GLOB. (P<0.2, P>0.05)[Table 3]
Multiple categorical variables included age, BMI, fracture site, preoperative stay, LYN, and PLT. In the multivariate regression analysis, the age group < 50 years was taken as dummy variable. BMI, LYM and PLT were used as dummy variables in the normal group. Foot fracture was used as dummy variable for fracture site. The preoperative stay group ≤ 2 days was used as dummy variable. Analysis results show that the significant risk factors for gram-negative bacterial infection occurrence are lower TP (odds ratio [OR], 4.066; 95% CI, 1.217-13.583) and higher WBC (OR, 3.133; 95% CI, 1.291-7.605).
Risk factors:
Univariate analysis revealed that the significant risk factors for development of SSIs after internal fixation of limb fractures were heart disease, diabetes mellitus, rheumatic diseases, current smoking, alcohol abuse, mechanism, fracture site, nerve injury at the fracture site, vascular injury at the fracture site, skin contusin at the fracture site, fracture type, ASA index, preoperative stay, intraoperative blood transfusion, postoperative drainage use, WBC, NEUT, LYM, RBC, HGB, PLT, blood glucose, TP and ALB. (P<0.05) The approximately risk factors were BMI, chronic obstructive pulmonary disease, cerebrovascular disease and GLOB. (P<0.2, P>0.05)
In the multivariate logistic regression model, the processing of multiple classification variables was the same as the previous part and the results had been detailed in Table 4. Our results show that the significant risk factors for SSI occurrence were current smoking, high-energy injury, femoral fracture, tibia and fibula fracture, vascular injury at the fracture site, skin contusin at the fracture site, hypohemoglobin. [Table 4]