Comparing Outcomes of Total Hip Arthroplasty for Displaced Neck of Femur Fractures in Elderly Patients Utilizing Dual Mobility Cups and Conventional Implants: A Single Center Retrospective Study of 129 Patients.

Introduction: Studies comparing the use of total hip arthroplasty (THA) with conventional implants and hemiarthroplasty for displaced femoral neck fractures (DFNF) have reported better patient satisfaction scores and outcomes in the former, but also significant dislocation rates (6.9-13%).The total hip arthroplasty with dual mobility cup (THA-DMC) design is mechanically proven to increase the hip range of motion and jump distance to dislocation relative to conventional implants. Despite its potential benefit, clinical studies analyzing the use of THA-DMC in the treatment of DFNF in comparison to conventional THA within the Asian population are still limited. Our study aims to compare the rate of complications and functional outcomes between the 2 implants in the treatment of DFNF. Materials and Methods: This was a retrospective cohort study conducted in a single tertiary care institution. From January 2015 to May 2020, data from 129 consecutive patients who satisfied the inclusion criteria and underwent either a THA or THA-DMC for DFNF were collected and divided into 2 groups. All patients received a standardized post-operative treatment and follow-up regime. Both groups of patients were assessed for post-operative complications such as dislocation, peri-prosthetic fractures, surgical site infections, medical complications. Their functional outcomes as well as patient-reported outcome scores were also assessed via the SF-36 score and Oxford hip score questionnaires at 6 months and 1 year. Results: A total of 42 patients with dual mobility implants and 87 patients with conventional implants were recruited. There was no dislocation in the THA-DMC group while there were 4 cases (4/87, 4.6%) of dislocation in the THA group. Regarding post-operative function, both groups had comparable functional outcomes. There were no statistically significant differences between the patient-reported outcome scores (Oxford hip score and SF-36) at 6 months and 1 year. Conclusion: We report promising short-term outcomes utilizing dual mobility implants in total hip arthroplasty for the treatment of DFNFs.