**6.5 Hydroxyproline determination**

Mean value of hydroxyproline in both groups was 13.9 mg/g (±10.2 SD), and in controls, 55.6 mg/g (±38.6 SD) ( p<0.013).

#### p<0.001

Fig. 6. The concentration of lipid peroxidation product - malondialdehyde in joint fluid. Values were measured in nmol/L. The lower and upper lines in the boxes represent the 25th and 75th percentiles, respectively, with the median marked in the box.

## **6.6 Metal particle analysis**

The tissue concentrations of the different metals for the Co-Cr and Ti-alloy prostheses are shown in Table 2. The mean level of MDA in the 23 implants made of titanium alloy was 0.059 µg/mg, and of the 9 implants made of Co-Cr alloy, 0.023 µg/mg. However, this difference was not significant (p=0.145).


\* p<0.013 in comparison between groups

Table 2. Concentrations of various metals in periprosthetic tissues from Co-Cr alloy and titanium alloy prostheses. Values measured in µg/g wet tissue. Data represented as mean ±SD.
