Can cemented dual-mobility cups be used without a reinforcement device in cases of mild acetabular bone stock alteration in total hip arthroplasty?

Introduction: Cemented versions of dual-mobility cups (DMCs), helpful in cases of bone stock alteration, are usually used in association with a reinforcement device. To simplify the intervention in elderly subjects or those with a poor bone stock, the cups can be cemented directly into the bone, but the long-term result remains uncertain. We conducted a retrospective study in this population so as to: (1) assess whether cemented fixation of a DMC without a reinforcement device leads to a higher loosening rate, (2) confirm its efficacy in preventing dislocations in subjects at high risk of instability, and (3) measure the functional results. Hypothesis: Cemented fixation of a DMC is reliable in cases of moderate alteration of bone stock. Material and methods: Sixty-four patients (66 hips) undergoing implantation of a cemented DMC(Saturne) without a reinforcement device were included in this single-center retrospective study. Theirmean age was 79.8 years (range, 40-95 years). The indications varied: hip osteoarthritis (30.3%), prosthesis revision (44.0%), and trauma (25.8%). The patients were evaluated radiologically and clinically at followup. The main evaluation criterion was the revision rate for aseptic loosening. Dislocations, the infection rate, and the Postel Merle d'Aubign (PMA) score were noted. Results: At the mean follow-up of 4.2 years, three (4.6%) patients had been lost to follow-up and 22(33.3%) had died. There was one case of aseptic loosening (1.5%). Cup survival was 98% at 5 years (95% CI[ 94-100]). There were no dislocations. There was one revision for infection. The mean PMA score was 15.5 (range, 9-18). Discussion: The frequency of acetabular loosening was comparable to the frequency in cemented DMCs with a reinforcement device. A cemented DMC without a reinforcement device is possible and is a simple and viable option when there is moderate bone stock alteration. Level of evidence: IV, retrospective cohort study. (C) 2015 Elsevier Masson SAS. All rights reserved.