Midterm Outcomes of a Monoblock Dual-Mobility Cup Cemented into a Fully Porous Acetabular Component in Revision Total Hip Arthroplasty

Abstract

Utilization of dual-mobility (DM) constructs has been a promising management option to address the risk of hip instability after complex revision total hip arthroplasty (rTHA). The aim of this study is to report a minimum 2-year outcome and survivorship of a monoblock DM cup cemented in a fully porous acetabular shell in complex acetabular rTHA cases. A retrospective review of 76 patients who underwent rTHA with a novel construct that utilized an inner DM cup cemented into a fully porous outer acetabular metal shell was conducted. Demographics, radiographic, and clinical outcomes such as readmissions, dislocation, and revisions were collected. Survivorship was analyzed by the Kaplan–Meier (KM) method. Thirty cases with a minimum of 2-year follow-up were included. Patients were, on average, 65.17 ± 10.26 years old with a mean body mass index of 28.55 ± 6.33 kg/m2. Seven patients (23.3%) required reoperations. Four patients underwent acetabular revision (periprosthetic joint infection: n = 2 [6.7%]; dislocation: n = 1 [3.3%]; aseptic loosening [fully porous cup]: n = 1[3.3%]). Three patients underwent reoperation without acetabular implant revision (debridement, antibiotics, and implant retention for prosthetic joint infection: n = 2 [6.7%]; femoral periprosthetic fracture: n = 1 [3.3%]). KM survivorship analysis of all-cause acetabular revision showed survival rates of 96.7% at 6 months, 93.3% at 1 year, and 89.7% at 2 years. KM survivorship of aseptic acetabular revision showed rates of 96.7% at 1 year and 92.9% at 2 years. KM analysis of acetabular cup fixation showed rates of 100% at 1 year and 96.2% at 2 years. The rate of dislocation in our cohort was 3.3% (1 out of 30). The use of a DM acetabular cup cemented into a fully porous acetabular revision shell in complex rTHA cases has a low risk of instability and loosening at 2 years with excellent mid-term implant survivorship. The use of this construct is a good option in patients with complex acetabular reconstruction and an elevated risk for instability. This was a retrospective cohort study with a level III evidence.