Use of a monoblock dual-mobility acetabular component in primary total hip arthroplasty in patients at high risk of dislocation.

INTRODUCTION Dislocation is amongst the most common complications following total hip arthroplasty (THA). Dual-mobility bearings have been suggested as one way to reduce the risk of dislocation, particularly among patients at increased risk. The purpose of this study was to determine the outcomes of a monoblock dual-mobility shell for patients at high risk for dislocation following primary THA. METHODS A total of 155 primary THAs with a monoblock, cementless dual-mobility acetabular component were performed in patients at high risk for dislocation. Two patients died prior to their two-year follow-up. The remaining 153 THAs were followed for a mean of 5.1 years (range: 2.1 to 9.3). RESULTS There were no dislocations; however, four patients underwent revision surgery: one for an early periprosthetic acetabular fracture, one for an early periprosthetic femoral fracture, one for a late periprosthetic femoral fracture, and one for leg-length discrepancy. Intraoperative complications included one periprosthetic acetabular fracture treated with protected weight-bearing and one intraoperative proximal femoral fracture treated with cerclage wiring. Harris Hip Scores improved from a mean of 42.4 points preoperatively to a mean of 82.4 points postoperatively (p < 0.001). No cups were radiographically loose. At a mean follow-up of 5.1 years, survivorship of the acetabular component was 99.3% (95% CI, 98.1-100%) and survivorship without any reoperation was 97.4% (95% CI, 95.9-100%). DISCUSSION Although there were no dislocations in this high-risk population, periprosthetic fractures of the femur and acetabulum were common with the implants utilised.