Early intramedullary fracture stabilization results in prolonged pulmonary damage in a rodent multiple trauma model

Abstract text (incl. references and figure legends)

Introduction In polytraumatized patients, severe pulmonary complications can be promoted by either post-traumatic hyperinflammation or immunosuppression. This fragile immunological situation can be disbalanced by operative procedures, potentially impairing the pulmonary recovery.¹ Thus, particularly in patients with a severe blunt chest trauma, the operative concept of damage control orthopedics(DCO) to minimize the perioperative inflammation competes with the early total care(ETC) concept, that is preferred in patients with different trauma patterns.² In this study, we assessed the influence of the operative strategy on pulmonary recovery in a rodent, multiple trauma model.

Materials & Methods Male Sprague Dawley rats(n=24,14 weeks old) received a blunt chest trauma(TxT), traumatic hemorrhage(TH), and a femoral shaft fracture. Subsequent fracture stabilization was performed with either intramedullary nailing(IF, n=9) or external fixation(EF, n=9) with switch to IF at day 6 after trauma. Sham groups(n=6) underwent analgosedation only. Histological pulmonary damage was examined blinded 7 and 21 days after the trauma, using the Lung injury score(LIS) and modified LIS (mLIS).

Results No significant differences were found between IF and EF at day 7(0.23 vs. 0.19;p=0.67). However, LIS and mLIS were higher in the IF group after 21 days compared to the EF group(0.35 vs. 0.29;p=0.11 and 1.64 vs. 1.33;p=0.19). Differences in mLIS and LIS became significant, excluding markers of an early immune response. Equal changes were observed in circulating inflammatory mediators.

Conclusion Early treatment choices effect the delayed pulmonary recovery after trauma, while the secondary switch towards IF did not result in additional pulmonal damage. In patients suffering from polytrauma with severe TxT and TH, primary EF could lead to an improved pulmonary recovery.

References ¹Hofman,M. et al. EJTES, 2020 ²Pape, H-C. et al. Injury, 2019. Granted by the AO Trauma Germany foundation.

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