Minimum 7-Year Outcomes of Dual Mobility Acetabular Cups in Total Hip Arthroplasty Patients

Abstract

Abstract Modular dual mobility cups have been developed to potentially address postoperative hip instability, which can occur in nearly 20% of all revision total hip arthroplasty (THA) patients. By having a prosthetic construct that contains two points of articulation between the femoral head and liner and between the liner and shell, joint stability can be increased. The purpose of this study was to report on dual mobility cup survivorships, patient satisfaction outcomes, complications, and radiographic outcomes at a minimum 7-year follow-up. A high-volume academic surgeon performed a total of 143 consecutive dual mobility primary THAs on patients who had a minimum follow-up of 7 years (range, 7–8.5 years). The study cohort consisted of 77 females (54%) and 66 males (46%) who had a mean age of 65 years (range, 34–90 years). Aseptic, septic, and all-cause survivorship was determined by Kaplan-Meier analysis. Harris Hip Scores (HHS), postoperative complications, and radiographs were also assessed. No cup failures were observed. Overall, septic survivorship was 99.3% (95% confidence interval [CI]: 0.98–1.0) and all-cause survivorship was 98.6% (95% CI: 0.97–1.0). Two patients (1.4%) required revision surgery unrelated to the use of a modular dual mobility cup. Of these, one patient experienced femoral stem loosening and the other developed a periprosthetic infection that was treated with a two-stage revision. The mean total HHS was above 95 points at the most recent follow-up. Three patients (2.3%) experienced medical complications, including two deep vein thromboses and one for nonfatal pulmonary embolism. Radiographic evidence revealed incomplete seating of the metallic liner in one patient. Dual mobility cups were developed in an attempt to decrease the rate of instability following THA. The results from this study indicate that excellent clinical and patient-reported outcomes can be achieved at 7-year follow-up in patients who undergo THA with a dual mobility cup. Therefore, dual mobility cups appear to be an appropriate treatment option for primary THA.