Table 2.

RSA results: head penetration (linear wear) at ten years in mm (95% CI), cup movements as translations in mm (95% CI) and rotations in degrees (95% CI). Precisions as mean difference between double examinations and level of significance

Wear results	Cobalt-chrome		Alumina		Precision (SD)	Significance
Proximal (y-axis)	0.96 (0.68–1.23)		0.42 (0.30–0.53)		0.08 (0.1)	P < 0.001
3D (x + y + z-axis)	1.07 (0.79–1.35)		0.53 (0.38–0.63)			P < 0.001
Subgroup	SHP	SP2	Cemex	Palacos
Proximal (y-axis)	1.10 (0.74–1.47)	0.78 (0.31–1.25)	0.40 (0.23–0.57)	0.43 (0.25–0.62)
3D (x + y + z-axis)	1.17 (0.80–1.53)	0.96 (0.44–1.47)	0.49 (0.32–0.65)	0.52 (0.33–0.72)
Cup movements
Translation x-axis	0.43 (0.17–0.69)		0.28 (0.17–0.40)		0.04 (0.05)	P = 0.19
Translation y-axis	0.71 (0.27–1.14)		0.33 (0.22–0.44)		0.03 (0.06)	P = 0.63
Translation z-axis	0.35 (0.20–0.51)		0.27 (0.16–0.39)		0.08 (0.13)	P = 0.32
Rotation x-axis	0.82 (0.36–1.29)		0.46 (0.27–0.64)		0.28 (0.74)	P = 0.05
Rotation y-axis	0.83 (0.34–1.32)		0.47 (0.24–0.70)		0.28 (0.46)	P = 0.06
Rotation z-axis	1.43 (0.18–2.68)		0.66 (0.41–0.92)		0.15 (0.40)	P = 0.36

RSA radiostereometry, CI confidence interval, SD standard deviation