Table 2.

Risk, risk ratio, and risk difference for dislocation within 6 months according to type of cup

Dislocation	Dual-mobility (n = 150)	Unipolar (n = 166)	Unadjusted risk ratio (95% CI)	p-value	Adjusted risk ratio (95% CI)	p-value	Unadjusted risk difference (95% CI)	p-value	Number needed to treat
Within 6 months (%)	4 (2.7)	13 (7.8)	0.34 (0.11–1.02)	0.06	0.28 (0.09–0.87)	0.03	−5.1 (−9.9 to −0.3)	0.04	19