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Dual-Mobility Total Hip Arthroplasty to Decrease the Risk of Dislocation

March 01, 2020

Contributors: Antonio Moroni; Salvatore Mosca; Riccardo Orsini, MD; Giovanni Micera, MD

Keywords: bearing surfaces; Dislocations; Outcomes; Radiographic Analysis

Introduction Dual-mobility acetabular cups were designed to decrease prosthetic instability, and the use of dual-mobility acetabular cups for primary and revision total hip arthroplasty (THA) has increased in popularity. Instability accounts for more than 20% of all revision THA procedures. Dual-mobility implants are associated with many advantages, including decreased risk of dislocation with a posterolateral approach, increased range of motion, decreased wear because of low friction, and decreased shear forces at the bone-implant interface. Dual-mobility acetabular cups typically are indicated in patients with a femoral neck fracture. In primary THA, dual-mobility acetabular cups are useful in elderly patients, noncompliant patients, patients with a bone tumor, patients with joint laxity, patients with rheumatoid arthritis, and patients with a congenital hip dysplasia. In revision THA, dual-mobility acetabular cups are useful in patients with recurrent dislocation and patients in whom THA fails because of bone deficiency or muscle injury. Objective This video analyzes the midterm radiographic and functional results (minimum follow-up of 6 years) of our series of patients who underwent THA with the use of a dual-mobility cup. Study Design and Methods The series included 91 consecutive patients who underwent THA via a posterolateral approach between June 2011 and January 2014. Of the 91 patients, 49 were female (53.85%) and 42 were male (46.15%). Of the 91 patients, 75 had end-stage hip osteoarthritis (82.4%), nine had rheumatoid arthritis, four had DCA, and three had a history of poliomyelitis. A Polarcup dual-mobility hip system (Smith & Nephew) was used. The mean patient age at the time of surgery was 70 years (range, 29 years to 89 years). Implants included 14 cemented dual-mobility cups, 77 noncemented dual-mobility cups, 55 cemented stems, and 36 noncemented stems. The mean preoperative Harris hip score was 42.7 (range, 32.2 to 68.2). We assessed patients at 1 month, 6 months, and 1 year postoperatively and every subsequent 2 years, obtaining radiographs and performing a clinical examination. Results Three patients were lost to follow-up. Death from causes unrelated to the study occurred in four patients. The mean Harris hip score obtained at a follow-up of 1 year was 78.7. No signs of periprosthetic bone rarefaction were observed. No major complications occurred, and no implant revision surgeries were performed. Discussion This study confirms good midterm clinical and radiographic results in patients who undergo dual-mobility THA. We believe that dual-mobility THA is an effective solution to decrease the risk of dislocation, and several studies have reported similar good results.