PurposePost-operative complications following fixation of pelvic fractures can lead to mortality and increased morbidity. Available literature regarding complications is heterogeneous and knowledge on risk factors is limited. This study aims to identify the most common post-operative complications and their possible risk factors following pelvic fracture surgery.MethodsA retrospective cohort study was performed in two level-1 trauma centers in the Netherlands between January 2015 and January 2021. Included patients were all adult patients (≥ 18 years) with an operatively treated pelvic fracture (pelvic ring and/or acetabular fractures). Post-operative complications included surgical site infections (SSI), material-related complications, neurological complications, malunion/non-union and performed reoperations. A forward stepwise multivariable logistic regression analysis was used to identify any risk factors associated with these complications.ResultsComplications occurred in 55 (24%) of the 233 included patients. SSI’s were most common, occurring in 34 (15%) patients. Duration of surgery (odds ratio 1.01 per minute, 95% confidence interval 1.00–1.01) and obesity (odds ratio 1.10 per BMI point, 95% confidence interval 1.29–7.52) were independent risk factors for development of SSI. Less common post-operative complications were material-related complications (8%) and neurological damage (5%).ConclusionLimiting operation time by using less invasive and less time-consuming surgical approaches may reduce the risk of SSI. More awareness and post-operative screening for early signs of SSI is mandatory, especially in obese patients. Future research should include large prospective patient cohorts to determine risk factors for other post-operative complications associated with pelvic fracture surgery.