Stabilization of femoral shaft fractures is a controversial issue in the management of patients with multiple trauma. Intramedullary nailing usually is preferred primarily; in recent years, however, pulmonary complications (e.g., ARDS) have been reported that were attributed to the reaming procedure. To study the effects of different nailing methods in a model of severe trauma, hemorrhagic shock and lung contusion were created at day 1 in sheep prepared by the method described by Staub. After recuperation (day 3) the animals in the study group (group 1) underwent intramedullary nailing of a closed femur without prior reaming; group 2 was treated with reaming and nailing according to AO standards. The reaming procedure led to an acute increase of pulmonary arterial pressure only in group 2 (19.8 ± 2.1 to 31.0 ± 4.6 mm Hg). Pulmonary triglyceride levels increased at parallel time points from 18.27 ± 2.3 to 33.04 ± 7.37 mg/dL only in group 2. Stimulatory capacity of polymorphonuclear leukocytes (PMNL) increased in the study group and decreased in controls (group 1: 2.652 ± 0.23 x 106 cpm to 3.387 ± 1.34 x 106 cpm; group 2: 2.699 ± 0.34 x 106 cpm to 2.460 ± 0.187 x 106 cpm). Intramedutery nailing caused an increase of lung capillary permeability in both groups; in the study group less damage was seen (group 1:0.390 ± 0.0006 to 0.354 ± 0.011; group 2:0.391 ± 0.0004 to 0.336 ± 0.015; p < 0.05). Intramedullary nailing after severe shock and lung contusion causes lung damage as a result of PMNL activation and triglyceride embolism; these effects are significantly less if nailing is performed without prior reaming.
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