Power and data analysis: migration of the Avantage® dual-mobility cups is the primary endpoint. Based on the standard dirivation (SD) of 0.6mm The median maximum total point motion (MTPM) and clinically relevant difference of 0.6mm MTPM, significance level <0.05 and power of 90 the ample size is calculated for 22 patients per group, but because of patient age and risk of death and drop-out inclusion will count 30 patients per group. Secondary endpoints are polyethylene wear, activity, complications, and functional outcome by clinical examination (HHS) and PROM (OHS, EQ5D). All of the applied methodologies are available, accessible and validated at Holstebro Regional Hospital.