TRANSESOPHAGEAL ECHOCARDIOGRAPHIC MONITORED EVENTS DURING TOTAL KNEE ARTHROPLASTY

Although the risk of pulmonary embolism or other embolic events associ ated with total joint arthroplasty have been recorded for some time, t o date no direct means of monitoring these events in human arthroplast y have been reported. The authors used transesophageal echocardiograph y to monitor directly the release of embolic particles into the circul atory system during the course of total knee arthroplasty. The transes ophageal echocardiography, in conjunction with intramedullary instrume ntation, revealed that showers of embolic particles entered the heart in repeated and unpredictable patterns during the course of convention al intramedullary instrumented total knee procedures. In response to t he presence of these embolic showers in the heart, an extramedullary p neumatically positioned system of instrumentation permitting automatic and accurate alignment of the knee with the mechanical axis of the fe mur has been developed. This new instrumentation establishes proper kn ee kinematics by semiautomatically determining and maintaining accurat e positioning of the femoral component along the mechanical axis of th e knee. Qualitative and quantitative monitoring of embolic events usin g transesophageal echocardiography in conjunction with conventional in tramedullary and the new instrumentation suggests that the embolic ris k is substantially reduced using the new procedure. Furthermore, the n ew extramedullary instrumentation was able to align the femoral knee c omponent to within 1 degrees of the mechanical axis in an initial seri es of 25 procedures. Excellent component alignment in conjunction with a substantially reduced quantity of embolic particles in the right he art as seen using transesophageal echocardiography was achieved using the newly developed extramedullary positioning and alignment arm.