[Embolism and intramedullary femoral surgery]

All intramedullary femoral surgery entails embolic phenomena which explain peroperative collapses formally known as bone cement implantation syndrome, as well as perioperative fat embolism syndromes. Locally, the bigger the cavity is, the higher the number of accidents: 2.5-5 per cent for GUEPAR hinged-knee prosthesis, 1.75 per cent for total hip arthroplasty with long stem, and 0.1 per cent during classic THA with cement limited to the metaphysis. Anomalies in bone vascularization also increase risk: 10.5-13 per cent during prophylactic nailing for shaft metastases, 1-11.5 per cent during hemiarthroplasty cemented in osteoporotic bone of femoral neck fractures, and only 0.1 per cent during THA implanted because of arthrosis. Not only cement, but also rods, reamers, nails, implants, ultrasonic tool for cement extraction, increase the pressure inside the cavity. Methylmethacrylate is no longer the only incriminated factor, even if it is responsible for a major part of the compressive load. The intensity and duration of the pressure are correlated with the number of embolic phenomena and with measured cardiopulmonary parameters. The intracavity fat content is expelled (an empty cavity, as in THA revision, does not lead to embolic phenomena). Then filters through the intraosseous veins whose diameter limit the size of the extruded embolic phenomena. The ultrasonography of the inferior vena cava shows innumerable fine particles and thrombi which are already organized under the influence of procoagulant factors released from the operative shield and which remain crumbly. These emboli cross the cardiac cavities. Transesophageal echocardiography (TEE), of recent use, does quantify the amount of right atrial filling, duration of echogenesis and size of particles: the result is higher in patients who underwent cemented versus noncemented THA: however the embolism score is no an indicator of seriousness because it is not correlated with cardiorespiratory manifestations; TEE shows only one fourth of the patent foramen ovale, whereas the atrial septal defect is surely one of the most efficient systemic invasion mechanisms to produce perioperative fat embolism. Lung response is most often asymptomatic, even if all patients undergoing intramedullary surgery display an increase in pulmonary vascular resistance which is managed by the right heart only, as well as pulmonary (and sometimes systemic) microvascular fat obstruction. Common operating room monitoring procedures do not detect successive embolic phenomena before they cause pulmonary arterial hypertension which then has repercussions on the left heart and in turn causes peroperative hemodynamic accidents. Only pulmonary arterial pressure measurement with a Swan-Ganz catheter gives early and durable signs of an intolerance to embolic load. Preventive treatment is surgical as there is an inverse relation between embolic marrow and marrow eliminated by large volume washes (which is often more effective than draining). Cement indications in older patients as well as the choice of fixation techniques in femoral fractures must take into account the cardio-pulmonary condition of the patient. Resuscitation procedures dealing with these complications end in the patient's death in half of the cases.