Abstract
Study Purpose To assess clinical cognitive function and measure cerebral embolic load following primary cemented hip arthroplasty.
Methods 34 primary cemented hip arthroplasty patients (mean age 69.9 (SD 11.0)0 and no history of cerebrovascular disease, underwent cognitive assessment before and after (day 4) surgery. Testing included: Verbal fluency and speed (Control Oral Word Association Test); Working memory to assess immediate and delayed recall (Weschler Memory Scale III); Attention and mental processing speeds (Colour Trails 1& 2). A one sample Wilcoxon signed rank test compared median differences before and after surgery. A sub-group of 20 patients had intra-operative transcranial Doppler ultrasound monitoring of the middle cerebral artery for embolic signals. A marker of neuronal injury (S-100B protein) was measured pre-operatively and at 0, 24 and 48 hours following surgery.
Results A significant difference was noted in Colour Trails tests 1& 2 following hip arthroplasty with P values (C.I.) of 0.002 (−21, −4) and 0.023 (−15.5, −1.0) respectively.
Using established emboli criteria 10 (50%) patients had true cerebral emboli with a range from 1 to 550 signals (median 2.5 interquartile range (IQ) 2 to 12.5). S-100B levels increased from a pre-operative median (IQ) of 0.15 microg/L (0.12 to 0.20) to a peak immediately following surgery of 1.88(1.36 to 4.24) returning to 0.26(0.18 to 0.37) by 48 hours (normal range: 0.03–0.15). Plotted scatter charts indicated no correlation between embolic load and cognitive dysfunction or with S-100B levels following surgery.
Conclusion Cognitive testing indicates deterioration in early measured attention, visual searching and mental processing speed shortly following hip arthroplasty. No direct correlation was found between cognitive dysfunction and cerebral embolic load.
Editoral Secretary Mr Peter Howard. Correspondence should be addressed to BHS at the Royal College of Surgeons, 35 - 43 Lincoln’s Inn Fields, London WC2A 3PN.
