Evaluation of echogenic emboli during total knee arthroplasty using transthoracic echocardiography

PURPOSE: Tranesophageal echocardiography or direct sampling of arterial and/or right atrial blood with histological evaluation are invasive techniques used to evaluate embolic material entering the heart during total knee arthroplasty (TKA). The aim of this study was to develop a non-invasive method of detecting and quantifying the embolic matter using transthoracic echocardiography and to apply this method to compare the incidence and severity of embolism between computer-navigated (N) and conventional (C) TKA done under tourniquet. METHODS: Twenty-eight patients (15 N-TKA and 13 C-TKA) were enrolled. Transthoracic echocardiography was performed in all standard views prior to surgery and continuously after the tourniquet release for monitoring the echodense particulates appearing in the right atrium. To estimate the severity of echogenic embolization, maximum absolute increase in luminosity after tourniquet release (peak embolic load) and area under the curve (AUC; total embolic load) were both calculated. RESULTS: Twenty-four (85%) had significant particulate matter in right atrium (median time from release of thigh tourniquet to peak embolization in right atrium: 18.0 s). Peak embolic load was lower in N-TKA than C-TKA [17.0 versus 35.0 arbitrary luminosity units, p = 0.03]. Total embolic load, by area under the curve, was lower in the N-TKA group. CONCLUSIONS: Perioperative particulate embolization during TKA can be quantified non-invasively with the use of transthoracic echocardiography and off-line image analysis. N-TKA, by virtue of avoiding intramedullary guides, causes lesser total embolic load and hence can lead to decreased the severity and incidence of this potentially fatal phenomenon. LEVEL OF EVIDENCE: II.