Modern cementless acetabular cups in total hip arthroplasty performed for primary osteoarthritis: a comparative registry study.

Introduction: Comparative studies evaluating the different material and surface finishing of acetabular components in total hip arthroplasty (THA) are lacking. Using a regional arthroplasty registry, the survival rates and the hazard ratios of different cups in THA performed for primary osteoarthritis were assessed, using endpoints: (1) every cup failure, (2) cup aseptic loosening, (3) periprosthetic infection.

Materials and methods: The inclusion criteria were: residing patients, THA for primary osteoarthritis, Delta-on-Delta bearings, head sizes 32 mm and 36 mm. Only the most implanted cementless cups were considered and were grouped according to material and surface finishing into three cohorts: 3D printed cups (I), ultraporous tantalum or titanium- coated cups (II), second-generation cups (III). 15,737 cups were included in the study: 9,862 cups (62.7%) in cohort I, 2,067 implants (13.1%) in cohort II, 3,808 implants (24.2%) in cohort III.

Results: The three cohorts achieved comparable general 10-year survival rates (p = 0.62). In I and II cohorts, the survival rates of the cup types within cohorts were analogous (p = 0.86 and p = 0.31), but not in cohort III (p = 0.004). The hazard ratios for overall failure adjusted for age and sex were similar among the cohorts. Regarding cup aseptic loosening, the three cohorts had similar rates (p = 0.48) and similar adjusted hazard ratios. With periprosthetic hip infection as endpoint, the survival rates and the adjusted hazard ratios of the three cohorts were comparable (p = 0.68).

Conclusions: 3D printed cups provided similar 10-year outcomes compared to ultraporous cups and second-generation cups, with no additional risks of aseptic loosening and infection.

Level of evidence: IV (therapeutic study).

Take home message: - 3D printed cups provided similar 10-year outcomes compared to ultraporous cups and second-generation cups. - There is no additional risks of aseptic loosening and infection.