Background Displaced femoral neck fractures (DFNFs) are increasingly common in elderly patients. Hip arthroplasty, the recommended treatment of DFNF, consists of the total hip arthroplasty (THA) and hemiarthroplasty (HA). THA is superior to HA in younger patients. However, there are concerns whether the more substantial surgical trauma and higher dislocation rate would trade off the advantages of THA due to frailty and lower physical demands in the elderly over 75 years. Objective This study was designed to compare the clinical score, dislocation rate, and functional outcome between the dual mobility total hip replacement and the bipolar hemiarthroplasty (BHA) in the treatment of FNFs and which of them is more successful. Patients and methods A comparative randomized prospective study was conducted on 50 patients with DFNFs. All cases were operated upon in Helwan University Hospitals, divided them into two equal groups: the first group was treated by total hip replacement with a dual mobility cup (DMC) and the second group was treated by BHA. Full analysis of history detailed examination and primarily samples are taken during the period study from February 2020 to April 2021. Results There is a statistically significant improvement in modified Harris hip score (MHHS) in the last follow-up at 9 months later in favor to DMC group compared with BHA group (P<0.001). The postoperative MHHS in the last follow-up of DMC ranged from 68 to 92 with the mean of 85.96±5.47, whereas in BHA group, ranged from 60 to 89 with the mean of 78.04±8.40. Conclusion THA may be a preferred management option for active elderly patients over 75 years, which can provide superior hip function and life quality with acceptable risks. Strict management should be followed to prevent dislocation after a THA, especially within the first 6 months.