Outcomes of revision total hip arthroplasty using the modular dual mobility acetabular system to treat recurrent dislocation

Background: Recurrent dislocation is a difficult complication after total hip arthroplasty (THA). This study aimed to report the clinical and radiographic outcomes of revision THA using the modular dual mobility (MDM) acetabular system to treat recurrent dislocation. Methods: Between March 2015 and February 2019, 34 revision THAs were performed using the MDM system for treating recurrent dislocation in a single institution. Of these, 32 revision THAs (32 patients) that satisfied a minimum follow-up of one year (mean, 4 years) were included in this study. Patient-reported outcomes, complication rates, and radiographic results were evaluated. Results: Seventeen patients (53.1%) had lumbar degenerative kyphosis, and six (18.8%) had surgically fused lumbar spines during the index operation. All acetabular components were revised, whereas femoral stems were retained in 29 patients (90.6%). No redislocation or intraprosthetic dislocation was noted after revision. One additional revision was required for acetabular loosening with periprosthetic joint infection. No additional revision was performed for aseptic loosening. A partial radiolucent line was found in two hips (6.3%) confined to one acetabular zone. Conclusions: Revision THA using the MDM system was effective in treating recurrent dislocation in a group of patients with a high prevalence of lumbar spinal pathology. During a mean follow-up of 4 years, one additional revision THA was performed for septic loosening and none for aseptic loosening.