Fat and bone marrow embolism in total hip arthroplasty.

A number of cardiovascular and pulmonary complications have been reported to occur occasionally after insertion of a total hip prosthesis. Of the proposed causes of these reactions, the possibility of fat embolism has received considerable support. The increase in intramedullary pressure, produced by the mechanical compression of the femoral canal during the insertion of the stem, seems to be the decisive pathogenic factor for the development of emboli. Surgeons' proclivity to deny the clinical relevance of intraoperative emboli is directly related to their awareness of and their attempt to avoid this phenomenon. Depending on the preoperative clinical condition of the patient, the cardiorespiratory impairment may be subclinical for those with good reserve, or clinical for those with poor reserve. In cases with preexisting cardiorespiratory diseases, severe embolism can also lead to death. Moreover, tissue thromboplastin from bone marrow forced into the draining veins of the proximal femur during insertion of the stem leads to activation of the clotting cascade, lesions of the venous endothelium, and thrombogenesis. A correlation was found between the embolic events observed using transesophageal echocardiography and the cardiopulmonary function of the patients during the perioperative period. A modified surgical technique was designed to reduce the intramedullary pressure during insertion of the stem to prevent intraoperative embolic events. Surgical prevention of fat and bone marrow embolism can also reduce the incidence of postoperative deep vein thrombosis.