Introduction and purpose: This study analyzes the clinical and radiographic results of two generations of the same uncemented acetabular component.

Materials and methods: The analysis comprised 83 Harris-Galante I (HGI) shells (with a 32 mm femoral head) and 93 Harris-Galante II shells (HGII) (with a 28 mm femoral head. Mean follow-up was 12.5 + 2.52 years for the HGI shells and 7.8 + years for the HGII ones. PE wear was assessed by means of image digitalization and computer software (AutoCAD).

Results: There were two cases of loosening amongst the HGI shells (Kaplan-Meier 96.9%) and one among the HGII ones (98.3%) (p = 0.7107). 4 PE replacements had to be performed due to wear in the HGI (90.7%). There were three dislocations of the PE insert in the HGI shells ( 79.7%) and one in the HGII ones (97.9%) (p = 0.883). Acetabular osteolysis was observed in 7 cases, out of which 5 were HGI and 2 HGII,. The osteolysis was related to a higher initial settling on the PE (position zero) ( p = 0.0062), a higher mean wear rate (p = 0.001), and a higher wear rate at the end of follow-up (p = 0.002). Position zero was 0.15 + 0.04 mm for HGI shells and 0.11 + 0.02 for HGII ones (p < 0.001). The mean wear rate was 0.13 + 0.23 mm/year and 0.11 + 0.09 respectively (p = 0.740). PE insert dislocation appeared after an average of 117 + 60.3 months, with a position zero of 0.15 mm for dislocated shells and y 0.13 mm for non-dislocated ones. The respective mean wear rates were 0.94 mm and 0.10 mm (p = 0.001).

Conclusions: Stable radiographical fixation was observed in the majority of shells of both generations. Osteolysis was related with higher wear. The second generation shows a lower position zero which leads to less wear at the end of follow-up, but not to a lower mean wear rate.