Reamed femoral nailing in sheep: Does irrigation and aspiration of intramedullary contents alter the systemic response?

Background: Reaming of the femoral canal has been demonstrated to introduce intramedullary contents into the circulation with subsequent pulmonary embolization. The aim of this study was to investigate whether this effect can be minimized by use of a reamer system that provides simultaneous irrigation and aspiration of intramedullary contents. Methods: A unilateral lung contusion was created and intramedullary femoral nailing was subsequently performed in eighteen female skeletally mature Merino sheep. The animals were divided into three groups, of six animals each, to receive one of three types of treatment: reamed femoral nailing; reaming, irrigation, and aspiration; and unreamed femoral nailing. Blood samples were obtained and a bronchoalveolar lavage was performed at baseline, immediately after creation of the lung contusion, immediately after intramedullary nailing, and at four hours after surgery. Pulmonary permeability, polymorphonuclear leukocyte activity, and systemic hemostatic response were measured. Lung specimens were obtained for histological evaluation. Results: At baseline and immediately after creation of the lung contusion, endothelial permeability was comparable among the three groups. At four hours postoperatively, pulmonary permeability was significantly higher in the group treated with reamed femoral nailing (urea/protein ratio; 256.7) than in the group treated with reaming, irrigation, and aspiration (urea/protein ratio, 91.5) and the group treated with unreamed femoral nailing (urea/protein, 110.64) (p < 0.05). The stimulatory capacity of the polymorphonuclear leukocytes was significantly decreased (p < 0.05) only in the group treated with reamed femoral nailing; the other two groups had no significant decrease postoperatively (p > 0.05). The D-dimer level at four hours postoperatively was significantly higher in the group treated with reamed femoral nailing than it was in the other two groups (p < 0.05). Histological examination showed that the grades of edema and polymorphonuclear leukocyte diapedesis were also highest in the group treated with reamed femoral nailing. Conclusions: It appears that, in the presence of a unilateral pulmonary injury, the systemic effects of intramedullary reaming of an intact femur can be minimized with use of a modified reamer design that simultaneously irrigates the canal and removes debris. Additional clinical validation of this reaming system is necessary.