Table IV.

Cox regression hazard ratios for revision due to aseptic loosening in socket and stem.

Parameter	Hazard ratio (95% CI) socket	Hazard ratio (95% CI) stem
Age, yrs
< 55	1.00 (reference)	1.00 (reference)
55 to < 64	0.68 (0.53 to 0.87)	0.91 (0.65 to 1.27)
65 to < 75	0.40 (0.31 to 0.50)	0.51 (0.37 to 0.70)
≥ 75	0.17 (0.13 to 0.22)	0.21 (0.15 to 0.29)
Sex
Female	1.00 (reference)	1.00 (reference)
Male	0.99 (0.87 to 1.11)	1.88 (1.63 to 2.17)
Head composition
Metal	1.00 (reference)	1.00 (reference)
Ceramic*	0.57 (0.46 to 0.71)	0.55 (0.42 to 0.71)
Total radiation (Mrad)
G1: no radiation	1.00 (reference)	1.00 (reference)
G2: < 5	0.62 (0.51 to 0.75)	0.75 (0.58 to 0.98)
G3: ≥ 5	0.32 (0.22 to 0.45)	0.46 (0.31 to 0.69)
Stem implantation
Cemented	1.00 (reference)	1.0 (reference)
Cementless	1.16	1.76 (1.36 to 2.28)

^*Includes femoral heads made of ceramicized metal (Oxinium).

CI, confidence interval.