Introduction: Total hip arthroplasty (THA) in patients with acetabular bone defects is associated with a high risk of dislocation and aseptic loosening. No studies to date have examined the use of uncemented and augmented dual mobility cups (DMC) in patients with acetabular defects. We hypothesized that the use of augmented DMC under these conditions would reduce the dislocation rate and lead to satisfactory bone integration in the medium term despite acetabular bone defects.
Materials and methods: This continuous multicenter study included all cases of augmented DMC performed between 2010 and 2017 in patients with acetabular bone loss (Paprosky 2A: 46%, 2B: 32%, 2C: 15% and 3A: 6%). The indications for implantation were revisions for cup aseptic loosening (AL) (n=45), femoral stem AL (n=3), bipolar AL (n=11), septic loosening (n=10), periprosthetic fracture (n=5), chronic dislocation (n=4), intraprosthetic dislocation (n=2), cup impingement (n=1), primary posttraumatic arthroplasty (n=8), and acetabular dysplasia (n=4). The clinical assessment consisted of the Harris hip score (HHS) and Merle d'Aubigné Postel score (MDP), along with preoperative and final follow-up radiographs. The primary endpoint was surgical revision for aseptic acetabular loosening or the occurrence of dislocation.
Results: Overall, 93 patients were reviewed at a mean follow-up of 5.3 ± 2.3 years [0, 10]. As of the last follow-up, the acetabular cup had been changed in five cases: 3 AL (3.2%) and 2 infections (2.1%). Thus the overall survivorship of the cup was 94.6% and the survivorship for AL was 96.8%. Three patients (3%) suffered a dislocation. At the last follow-up visit, the mean MDP and HHS scores were 14.75 and 72.15, respectively, which reflected significant improvements relative to the preoperative scores (p < 0.05).
Conclusion: Use of an uncemented and augmented DMC in cases of acetabular bone defect leads to satisfactory medium-term results with low dislocation and loosening rates. We recommend its use in these cases.