A COMPARISON OF CEMENTED DUAL MOBILITY VERSUS CEMENTED MONOBLOC POLYETHYLENE CUPS IN ACETABULAR REVISION SURGERY WITH IMPACTION BONE GRAFTING

In revision hip surgery, a dual mobility (DM) construct aims to improve stability, however there are concerns about torque transmission to the implant-bone interface which may cause failure due to loosening. The use of cemented dual mobility cups in acetabular revisions with impaction bone grafting has not been well studied. We aimed to compare cemented DM versus cemented monobloc polyethylene (PE) cups. Between 1/12/2014 – 30/1/2023, 1,949 acetabular revisions were performed at our Trust. Of these, we included cemented revisions (SERF; DM and Marathon; PE) that used impaction bone grafting, for Paprosky 1, 2a, 2b and 2c defects, with no more than one augment, and a minimum one year follow up. Due to differences in demographics, we used propensity score matching to ensure both groups were matched for age, gender, BMI, ASA, reason for revision and Paprosky classification. Our outcomes of interest were loosening, presence of radiolucent lines, dislocation, periprosthetic fracture, re-revisions and mortality. We compared 82 DM with 329 PE cups. Mean follow up was 43±27 months. There was no statistically significant difference in loosening (3/82 versus 32/329; p=0.1184), presence of radiolucent lines (15/79 versus 70/297; p=0.3869), dislocation (3/82 versus 12329; p=1.0000), periprosthetic fracture (1/82 versus 8/329; p=0.6947) or re-revision (3/82 versus 28/329; p=0.1649). 3-year and 5-year mortality were significantly higher in the PE group. Following propensity score matching, we compared 62 DM with 194 PE. There was no statistically significant difference in any of our outcomes of interest following matching. At a mean follow up of 43 months there was no difference in loosening, radiolucency, dislocation, periprosthetic fracture, re-revision rates or mortality when comparing matched cohorts of cemented DM cups to cemented PE cups, in acetabular revisions with the use of impacting bone grafting.