Obesity, Leukocytosis, Embolization, and Injury Severity Increase the Risk for Deep Postoperative Wound Infection After Pelvic and Acetabular Surgery

Objective: To determine if preoperative fever and leukocytosis without an established source of untreated infection are independent risk factors for the development of deep postoperative wound infection (DPWI) after surgical treatment of pelvic and acetabular fractures. Design: Retrospective chart and radiographic review; matched case-control comparison. Setting: Level 1 regional referral trauma center. Patients and Methods: Five hundred ninety-seven skeletally mature patients with pelvic and/or acetabular fractures requiring operative fixation (353 acetabular, 170 pelvic, and 74 combined acetabular and pelvic injuries). Retrospective chart review was performed analyzing for the following variables: injury severity score, preoperative fever, serum and urine white blood cell count; intensive care unit admission, previous infection, Morel-Lavallee lesions, pelvic arterial embolization, open fractures, intraoperative cell saver use, perioperative blood transfusions, subfascial drains, antibiotic use, and obesity [BMI (body mass index) >30]. Open pelvic or acetabular fractures were excluded. Main outcome measure was diagnosis of DPWI. Patients with a diagnosis of DPWI were then compared with a random 1: 4 matched cohort of patients without a history of DPWI. Patients were matched and grouped according to injury pattern, age, and surgical procedure. Statistical comparison of the 2 groups was performed using a Mann-Whitney test, Fisher exact test, and odds ratio (OR) with 95% confidence intervals and positive predictive values (PPVs). Results: Seventeen patients (2.8%) developed DPWI, distributed as 8 (2.3%) acetabular, 5 (2.9%) pelvic, and 4 (5.4%) pelvic-acetabular infections. Eighty patients met inclusion criteria for the matched cohort comparison. The median age of those patients with infection was 43 years (range 31-69) and those without infection were 41 years (range 24-71). Both groups were predominantly male (77% and 74% for the 2 groups, respectively). The average BMI and injury severity score of the case (infected) group were significantly higher than that of the control (noninfected) group. Of the variables examined, preoperative leukocytosis, obesity, blood transfusion, and interfacility transfer had a statistical association (P < 0.05) with DPWI after pelvic or acetabular surgery. Preoperative angioembolization reached near statistical significance (P = 0.07). However, determination of PPV and OR suggested that only obesity (OR 8, PPV 33%), obesity plus leukocytosis (OR 12, PPV 39%), and preoperative angioembolization (OR 11, PPV 67%) were strong predictors of postoperative infection. Although the infection rate for combined approaches was twice that of acetabular or pelvic surgery alone, this was not statistically significant. Conclusions: Based on the findings of this analysis, patients requiring preoperative angioembolization and having a BMI >30 have a significant increase in their risk of postoperative infection, particularly if associated with leukocytosis. Patients with both pelvic and acetabular fractures that require surgical treatment should be counseled that their risk for infection may be higher.