Dual mobility cup as a treatment of displaced femoral neck fractures in elderly: stability and function

Background The main goal in the treatment of femoral neck fractures in the elderly is to enable early mobilization. Hemiarthroplasty is considered the gold standard line of treatment. In the past decade, total hip replacement (THR) was introduced to the orthopedic community with the advantage of better pain relief and functional outcome. However, the reported dislocation rates after THR in femoral neck fractures remained higher than the rates after hemiarthroplasty. Nowadays, there is renewed interest in dual mobility cups to solve the problems of hip instabilities for various reasons. Dual mobility cups aim to decrease the dislocation rate by associating two articular surfaces: one with a larger diameter situated between a metallic cup and a polyethylene insert, thus utilizing the concept of a large head size to reduce dislocation, and the other one with a smaller diameter situated between the femoral head and the retentive polyethylene insert to achieve more mobility. The authors believe that the results of the dual mobility concept after femoral neck fractures are under-reported, with few papers discussing the outcome specifically in the Egyptian population. Aim This study was carried out to assess the dislocation rate and clinical results for cemented THR with a dual mobility cup as the treatment of femoral neck fractures in elderly patients, after a minimum period of 1 year. Settings and design A prospective case series study was carried out at El Hadara University Hospital, Alexandria University. Patients and methods This study included 31 patients (32 hips) with displaced femoral neck fractures who were admitted to El Hadara University Hospital, Alexandria, Egypt. Their mean age was 66.6±6.3 years. There were 15 females and 16 males. All the patients were treated using a cemented dual mobility cup for THR using the standard posterior approach. Functional assessment was performed using the Harris hip score (HHS) with the assistance of physiotherapists to avoid bias. Results No dislocations were encountered in this series over 1 year of follow-up. The mean operative time was 136.9 min. The average blood loss was 756.3 ml. The mean HHS improved over the follow-up period from 80.3±7.9 (95% confidence interval: 74–86) at 12 weeks to an average of 92.6±11.1 (95% confidence interval: 88.7–96.5) at the 1-year follow-up. This increase in HHS was not statistically significant (P=0.143). Conclusions Dual mobility cup THR is a good method for the treatment of displaced femoral neck fractures in the elderly as it provides good stability, pain relief, and good function.