Cognitive function and cerebral emboli after primary hip arthroplasty

Transcranial Doppler ultrasound has been used to detect cerebral emboli after hip arthroplasty. The cognitive effects of these embolic events are unclear. The aim of this study was to assess cognitive change after primary cemented hip arthroplasty using a range of neuropsychological tests and to measure intraoperative cerebral embolic load. Twenty primary cemented total hip arthroplasties underwent a series of cognitive tests before and at four days after surgery. A range of validated tests assessed: global cognitive function; verbal fluency and speed; immediate and delayed memory recall; attention and mental processing speeds. Intra-operative transcranial Doppler ultrasound monitoring of the middle cerebral artery for embolic signals was also performed. A one-sample Wilcoxon signed-rank test compared median cognitive results post-pre surgery and a Mann-Whitney U test established if there was a cognitive difference between those patients who had detectable cerebral emboli and those who did not. Scatter plot graphs were also used to establish any correlation between the embolic load and clinical cognitive dysfunction. A significant (p<0.01) difference was noted in specific tests assessing mental processing speed, visual searching and sustained and divided attention following surgery. Intra-operative cerebral embolic signals were detected in 11 out of 20 patients and the majority occurred with femoral component cementation and hip reduction. There was no difference in cognitive dysfunction between those patients who had detectable cerebral embolic signals and those who did not and there appeared to be no direct correlation between the size of the embolic load and the level of cognitive dysfunction.