[Detection and effects of bone marrow intravasations in operations in the area of the femoral marrow cavity].

In recent years, during total hip replacement and intramedullary nailing large sonographic echoes some centimeters in length have been observed on transesophageal echocardiography of the right heart. The echoes have always appeared after rise in pressure in the femoral cavity. The substrate of the echoes was not known. We could not imagine that particles of bone marrow of the size observed were passing through the vessels of the femur, but on the other hand there was no other suitable explanation. For clarification of the substrate of the sonographic echoes an animal study was performed in sheep. After the application of a known pressure on the femoral cavity the distal vena cava was investigated sonographically through a laparotomy; proximally blood was taken from the vein. The study identified the large sonographic echoes as "mixed emboli" consisting of a core of bone marrow and surrounding apposition of thrombotic material. The observations explain the frequent observations of pulmonary impairment after elevation of the intrafemoral pressure. It seems possible that the intravasation of bone marrow is involved in the pathogenesis of thrombosis after orthopedic surgery.