Concentration of metal elements in the blood and urine in the patients with cementless total knee arthroplasty

Titanium (Ti), cobalt (Co) and chromium (Cr) element concentrations in the whole blood and urine specimen in 40 patients with cementless total knee ar throplasty were determined by the electrothermal atomic absorption spectrop hotometry. Their ages ranged from 55 to 78 years (mean, 65 years). Twenty o f them had loosening of prosthesis and underwent revision surgery, includin g 4 subjects with Ti-6Al-4V alloy prosthesis and 16 subjects with Co-Cr-Mo alloy prosthesis. The other 20 patients had well-functioning stable prosthe sis, including 5 subjects with TI-6Al-4V alloy prosthesis and 15 subjects w ith Co-Cr-Mo alloy prosthesis. The mean duration of prostheses implantation in patients with loosened or well-functioning prostheses mere 6.5 and 4.0 years, respectively. The control group consisted of 20 age-matched normal s ubjects who did not undergo any metal implant surgery. Analysis of variance showed that the metal element concentrations in the whole blood, either Co , Cr or Ti, was statistically higher in the patients with loosened prosthes is than the other two groups. However, the metal element concentrations in the urine did not show any difference. The linear regression analysis showe d a moderate positive relationship between the metal element concentrations , either Co or Cr elements, in whole blood and urine only in the patients w ith loosened prostheses. In conclusion, elevated concentration of metal ele ments may indicate a loosening of prosthesis while the clinical significanc e of the metal element concentration in the urine needs further investigati on.