INTRAMEDULLARY PRESSURE CHANGES AND FAT INTRAVASATION DURING INTRAMEDULLARY NAILING - AN EXPERIMENTAL-STUDY IN SHEEP

In this study, intramedullary reaming and nailing were performed follo wing the insertion of pressure transducers in intact tibias and femora . The femur and tibia were instrumented in 12 sheep (group I) and both tibiae in four (group II). The eight procedures of group II were moni tored additionally using echocardiography to detect emboli. Intravasat ion of fat globules was demonstrated in the blood by the Gurd test and correlated with intramedullary pressure and with echocardiographic mo nitoring in group II. Medullary nailing was found to be always associa ted with a severe increase in intramedullary pressure, reaching an ave rage of 1126 mm Hg (304 to 1450 mm Hg) in the tibia and of 753 mm Hg ( 310 to 1126 mm Hg) in the femur during the first reaming procedures. P article or fat intravasation was greatest during nail insertion. This phenomenon did not depend on the rise in intramedullary pressure. Our findings indicate that fat and bone marrow intravasation occurs during reaming and nailing in long bones. The maximum embolization of marrow contents demonstrated by echocardiography is seen during nail inserti on independent of the changes in intramedullary pressure.