60 elderly patients with dementia and a displaced femoral neck fracture were randomized to receive a Quattro dual mobility cup in a total hip arthroplasty procedure or a hemi-arthroplasty procedure. The primary outcome of interest was dislocation rate at 1 year post-operation. Secondary outcomes of interest included reoperation rate, time to surgery, operative time, length of stay and the incidence of mortality at 30 days and 1 year post-operation. Whilst operative time was significantly longer in the total hip arthroplasty group, the incidence of dislocation was significantly lower compared to the hemi-arthroplasty group. No significant differences were observed between the two groups in the remaining outcomes.