Cerebral microemboli (ME) are frequently generated during major orthopaedic surgery. The primary objective of this study was applying novel transcranial Doppler (TCD) ultrasound software algorithm to quantify (ME load/15 minutes) and qualify (particulate vs. gaseous) ME, detected as high-intensity transient signals (HITS) in both middle cerebral arteries (MCAs) before and after orthopaedic surgery.