Because of a painful right-sided coxarthrosis a 57-year-old female patient underwent a cementless total arthroplasty under general anesthesia. Except for Asperger's syndrome and an occlusion of a vein in her left eye she stated no other diseases or complaints, especially no cardiac problems. Postoperatively she developed neurological symptoms of left-sided hemiparesis and hemihypesthesia. A cranial computer tomography was performed and a right-sided infarction of the thalamic region was found. A patent foramen ovale (PFO) and atrial septal aneurysm were detected 5 days later. The incidence of a PFO is given as 25% of the population. A paradoxical air embolism in the presence of a PFO is a feared complication in neurosurgical interventions in a semi-sitting or sitting position. Corpuscular emboli, such as bone, cement, fat or wound debris may be the reason for paradoxical embolisms in combination especially with partial or total hip replacement. The kind of embolism in the case described could not be clarified. Deep vein thrombosis or cardiac arrhythmia could be excluded. Therefore, it can be considered most likely that the operation site was the source of the embolism. The trigger for a paradoxical embolism is a reversal of the pressure difference between the right and left atria: normally the left atrial pressure exceeds the right atrial pressure by ca. 2-4 mm Hg, resulting possibly in a small clinically irrelevant left-to-right shunt. If the pulmonary arterial circulation is compromised and pulmonary vascular resistance increases, the pressure gradient between the left and right atria reverses and a right-to-left shunt can occur causing a paradoxical embolism. Positive end-expiratory pressure (PEEP) ventilation during anesthesia could be an important reason for a shunt reversal between the right and left atria and therefore favoring a paradoxical embolism but the pathophysiological role of PEEP has not yet been finally clarified.

Accumulating evidence implicates cerebral fat embolism (CFE) as a causative agent in post-operative confusion (POC). CFE occurs following orthopaedic procedures including, intra-medullary (IM) nailing and total joint arthroplasty (TJA). The incidence of CFE is high (59-100% TJA) and the resulting POC is associated with higher overall complication rates. Cognitive dysfunction improves in many patients but can persist - with potentially disastrous outcomes. The pathomechanics of CFE implicate circulating lipid micro-emboli (LME) that are forced from IM depots by instrumentation/nailing. Passage to the left side of the heart is possible through intra-cardiac or arteriovenous shunts in the lung. LME are propelled to the brain where they cause disruption via ischemia or by alterations in the blood-brain-barrier - causing cerebral oedema. Prevention of CFE follows established practices for preventing FES and consideration of additional techniques to remove resident fat and reduce IM pressures. When CFE occurs supportive treatment should be established.

Pulmonary embolism (PE) by solid particles is an infrequent complication encountered during orthopedic procedures. A patent foramen ovale (PFO) allows embolic material into the left-sided circulation, potentially affecting several organs. A case of a 33-year-old woman undergoing total proximal femur resection with megaprosthesis reconstruction is presented. Towards the end of surgery, cement was injected to stabilize the prosthesis. Echodense particulate matter was first seen in the right atrium, subsequently in the right ventricle, and also in significant quantities in the left atrium and ventricle. This was accompanied by significant changes in partial pressure of arterial oxygen. Despite the aforementioned disturbances, hemodynamic stability was observed throughout the event. Postoperative follow-up showed persistent hypoxemia but no other abnormalities. This intriguing case of embolism via particulate material in a patient with PFO during hip replacement surgery allows review of the physiology and pathophysiology of PE phenomena.

Cerebral embolism in patients undergoing total joint arthroplasty has an incidence rate of 0.5%. In those cases where cerebral emboli were confirmed, a venous-to-arterial circulation shunt, most commonly a patent foramen ovale, was identified. We report a case of severe cerebral fat emboli during cementless total hip arthroplasty in the absence of an intracardiac defect.

Paradoxical cerebral embolism (PCE) is defined to be a pathological condition in which emboli originating from the venous system reach the cerebral arterial circulation via the right-to-left (R-L) shunt. In patients with PCE, emboli originating from the venous system most commonly pass through the patent foramen ovale during Valsalva-provoking activities which increase the right atrial pressure above the left atrial pressure. The size of cerebral infarction caused by PCE is generally small, since the size of emboli which can pass through the R-L shunt is small. Here, we report a case of PCE which occluded the internal carotid artery (ICA).