INTRAMEDULLARY NAILING AND PULMONARY-EMBOLISM - DOES UNREAMED NAILINGPREVENT EMBOLIZATION - AN IN-VIVO STUDY IN RABBITS

Pulmonary embolism in reamed femoral nailing has been reported and dis cussed over recent years. Does an unreamed nailing technique with a so lid nail prevent this rare but serious complication of intramedullary fixation? rn an animal model in rabbits, we studied the pathophysiolog ic impact on pulmonary function and the impact on hemostasis of reamed and unreamed nailing of intact femora and tibiae, and of femoral frac ture in relation to intramedullary pressure. No statistical difference of Pao(2), Paco(2), and Pco(2et) was found in the femur whether a rea med or unreamed procedure was performed. Two of six animals with unrea med femoral nailing, one of six animal with reamed femoral nailing, an d one of five animals with a femoral fracture fulfilled four of four o r three of four criteria for embolization (increase of the difference of Paco(2) and Pco(2et), decrease of Pao(2), increase of blast cells i n central-venous blood and bone marrow/fat in histologic section of th e lungs and bone). Tibial nailing did not alter pulmonary function in either group. Intramedullary pressure was increased in all animals wit h perioperative impairment of pulmonary function (375 to 676 mbar). An alysis of the hemostatic results showed a significant difference of pl atelet activation in reamed versus unreamed nailing of the femur 1 hou r after nailing (p < 0.01) and a significant decrease of fibrinogen an d antithrombin III (p < 0.001/p < 0.01) in reamed femoral nailing. We conclude that unreamed nailing of the femur with a solid rod may also cause bone marrow embolization with alteration of pulmonary function a s long as an important increase of the intramedullary pressure is gene rated during the nailing procedure. Reaming induces a hemostatic activ ation, which seems not responsible for the immediate pulmonary impairm ent by bone marrow embolization, but may play a role in the postoperat ive course.