[Incidence, Diagnosis and Risk Factors for Fracture-Related Infection (FRI): 3-Year Experience of Level I Trauma Centre].

PURPOSE OF THE STUDY The study aims to determine the incidence of fracture-related infection (hereinafter referred to as the FRI) at a Level I trauma centre over a three-year period. It also aimed to determine the risk factors, to observe confirmatory and suggestive criteria in line with the applicable recommendations, and to evaluate the bacterial spectrum in a diagnosed FRI. MATERIAL AND METHODS It is a retrospective-prospective study carried out through studying the documentation. The study included all patients diagnosed with FRI and treated between 2019 and 2021, except for the patients with hand fractures since minor phalangeal fractures of the fingers were largely treated by the outpatient department, no osteosynthesis was performed in the operating room, and these patients were not followed up at our department. RESULTS The FRI incidence was 2.33% of all osteosyntheses performed at the Level 1 trauma centre in the period 2019-2021. The FRI was most often caused by pyogenic cocci agents and the FRI developed most frequently within 6 months after osteosynthesis. The site at risk was the lower limb region. The FRI incidence was most often indicated by suggestive clinical criteria (redness, secretion, pain) and radiological criteria (delayed healing, non-union). Overall, 42.19% of treated nonunions were later diagnosed as FRI. At the time of FRI diagnosis, the CRP values were normal in 21.7% of patients. DISCUSSION The FRI incidence rate in 2019-2021 was 2.33%, which corresponds with the values reported in other papers focusing on the incidence of infectious complications after osteosynthesis. Fang and Depypere reported 1-2% of infectious complications. The most common risk factors are open fractures, which account for 20.16% in our cohort. Ktistakis and Depypere describe the incidence of osteomyelitis in 30% of treated open fractures. In our cohort, the incidence of FRI was significantly higher in lower limb fractures. Bezstarosti, Wang and Pesch published similar results, with some deviations. The time from osteosynthesis to final FRI diagnosis varied from a few weeks to several years. In more than half of the patients the FRI developed within 6 months after performed osteosynthesis. Metsemakers and Fang refer to the very same trend. The CRP levels in the study population varied a lot. Xing-qi Zhao describes CRP as a less sensitive (sensitivity 65.6%) but more specific marker (specificity 75.4%). According to the available literature, the most common agents causing infectious complications of osteosynthesis are gram-positive cocci, S. aureus in particular. In our study, G+ pyogenic cocci were clearly the most commonly detected, which is consistent with the results of studies by Fang and Depypere, focused on the incidence of infectious complications. The most common FRI clinical manifestations included wound secretion, redness, swelling and pain. Furthermore, suggestive radiological criteria, especially delayed healing and non-union also indicated the FRI occurrence. According to Fang, the most common clinical manifestations of infectious complications include pain, swelling, redness and wound dehiscence. Fang reports that the most common radiologic findings are the periosteal reaction, loosening of the implant and delayed healing or non-union, which is consistent with our cohort. In the cohort of non-unions surgically treated at our department, FRI was subsequently confirmed in 42.19% of cases. CONCLUSIONS The incidence of FRI at Level 1 trauma centre was 2.33% of operated fractures in 2019-2021, with pyogenic cocci being the most common infectious agents. The FRI usually developed within 6 months after osteosynthesis. The typical site for the FRI development was the lower limb region, the ongoing FRI was indicated by suggestive clinical criteria (redness, secretion, pain) and radiological criteria (delayed healing and a non-union). Overall, 42.19% of treated non-unions were later diagnosed as FRI. Key words: fracture-related infection, FRI, suggestive criteria, confirmatory criteria, FRI diagnosis, microbial, microbiology spectrum, osteosynthesis, complications, non-union.