Objectives

One commonly used rat fracture model for bone and mineral research is a closed mid-shaft femur fracture as described by Bonnarens in 1984. Initially, this model was believed to create very reproducible fractures. However, there have been frequent reports of comminution and varying rates of complication. Given the importance of precise anticipation of those characteristics in laboratory research, we aimed to precisely estimate the rate of comminution, its importance and its effect on the amount of soft callus created. Furthermore, we aimed to precisely report the rate of complications such as death and infection.

Background: Bacterial translocation is defined as a phenomenon in which live bacteria cross the intestinal barrier and spread the other systemic organs after various type of traumatic insults such as hemorrhagic shock, burn, malnutrition and abdominal trauma. It has also been shown that multiple fractures of long bones associated with head injury promote bacterial translocation. Aim: To determine whether early internal fixation of long bone fractures helps to prevent bacterial translocation. Materials and methods: Thirty-seven male Sprague-Dawley rats were divided into three groups. 1) anesthesia only (control group, n=12); 2) anesthesia + tibia fracture + femur fracture + moderate head trauma (trauma group, n=14), and 3) anesthesia + fixation of both tibia and femur fractures + moderate head trauma (fixation group, n=11). Head injury was created by using Marmarou’s impaction-acceleration model and fractures were created by using a blunt guillotine. After 24 hours, mesenteric lymph nodes, liver, spleen and systemic blood samples were quantitatively cultured to detect bacterial translocation. Finally, ileum was cultured to determine the indigenous intestinal flora. Results: The most commonly translocating bacteria were enterococci, E.coli, and group D streptococci. The incidence of bacterial translocation was lower in fixation group (2/11) than the trauma group (10/14) (Fishers exact test, p=0.025). No statistical difference was detected between the control and the fixation group. The number of organs containing viable bacteria was significantly lower in the control and fixation groups than the trauma group (Mann Whitney U test, p=0.002). Conclusion: Multiple organ failure which is the most severe complication after trauma has a mortality rate of 50–70%. It is believed that MOF results from sepsis from organisms in the intestinal flora; a process termed bacterial translocation. Our data revealed that in case of multiple long bone fractures combined with moderate head injury, systemic translocation of the gut bacteria may be prevented by early internal fixation of the bones