Abstract
BackgroundIn the stabilization of femoral fractures in mono- and polytrauma, clinical practice has shown better care through intramedullary nailing. However, the reason why this is the case is not fully understood. In addition to concomitant injuries, the immunological aspect is increasingly coming to the fore. Neutrophil granulocytes (PMNL), in particular next to other immunological cell types, seem to be associated with the fracture healing processes. For this reason, the early phase after fracture (up to 72 h after trauma) near the fracture zone in muscle tissue was investigated in a pig model.Material and methodsA mono- and polytrauma pig model (sole femur fracture or blunt thoracic trauma, hemorrhagic shock, liver laceration, and femur fracture) was used to demonstrate the immunological situation through muscle biopsies and their analysis by histology and qRT-PCR during a 72 h follow-up phase. Two stabilization methods were used (intramedullary nail vs. external fixator) and compared with a nontraumatized sham group.ResultsMonotrauma shows higher PMNL numbers in muscle tissue compared with polytrauma (15.52 ± 5.39 mono vs. 8.23 ± 3.36 poly; p = 0.013), regardless of the treatment strategy. In contrast, polytrauma shows a longer lasting invasion of PMNL (24 h vs. 72 h). At 24 h in the case of monotrauma, the fracture treated with external fixation shows more PMNL than the fracture treated with intramedullary nailing (p = 0.026). This difference cannot be determined in polytrauma probably caused by a generalized immune response. Both monotrauma and polytrauma show a delayed PMNL increase in the muscle tissue of the uninjured side. The use of intramedullary nailing in monotrauma resulted in a significant increase in IL-6 (2 h after trauma) and IL-8 (24 and 48 h after trauma) transcription.ConclusionThe reduction of PMNL invasion into the nearby muscle tissue of a monotrauma femur fracture stabilized by intramedullary nailing supports the advantages found in everyday clinical practice and therefore underlines the usage of nailing. For the polytrauma situation, the fixation seems to play a minor role, possibly due to a generalized immune reaction.
Highlights
In the stabilization of femoral fractures in mono- and polytrauma, clinical practice has shown better care through intramedullary nailing
The reduction of PMNL invasion into the nearby muscle tissue of a monotrauma femur fracture stabi‐ lized by intramedullary nailing supports the advantages found in everyday clinical practice and underlines the usage of nailing
The main results of our study can be summarized as follows: 1. Monotrauma was associated with higher neutrophil counts in the muscle tissue compartment compared with polytrauma, whereas polytrauma resulted in a prolonged PMNL infiltration of the muscle tissue
Summary
In the stabilization of femoral fractures in mono- and polytrauma, clinical practice has shown better care through intramedullary nailing. Neutrophil granulocytes (PMNL), in particular next to other immunological cell types, seem to be associated with the fracture healing processes. For this reason, the early phase after fracture (up to 72 h after trauma) near the fracture zone in muscle tissue was investigated in a pig model. In the early pro-inflammatory phase of fracture healing, neutrophil granulocytes (PMNL) are one of the first immune cells recruited into the fracture site. There, they form an extracellular "emergency matrix" by releasing fibronectin, which provides a structure even before the migration of connective tissue cells [3]. The initiation of this mobilization and migration of PMNL depends on interleukin (IL)-8 [4, 5]
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