Outcomes of total hip arthroplasty using dualmobility cups for femoral neck fractures: a systematic review and meta-analysis

Objectives: Femoral neck fractures (FNFs), with up to 15% mortality, are prominent orthopaedic emergencies. After treating FNFs, dislocation is another challenge increasing morbidity, mortality and treatment costs substantially. The emerging dual-mobility cup (DMC) may decrease dislocation rates following total hip arthroplasty (THA) for FNFs. We performed a systematic review of literature reporting dislocation and mortality rates with DMC-THA for the treatment of FNFs. Methods: 2 authors independently searched PubMed (MEDLINE), Google Scholar and Cochrane library for studies reporting dislocation and mortality rates for FNFs treated with DMC-THA since inception up to January 2019. Data on outcomes of interest was extracted from all studies and assessed for eligibility for a meta-analysis. Results: Out of 522 search results, 18 studies were included in the systematic review and 4 in the meta-analysis. The mean rate of dislocation following DMC-THA for FNFs was found to be 1.87% +/- 2.11, with a 1-year mortality rate of 14.0% +/- 10.55. Results of meta-analysis showed that dislocation and 1-year postoperative mortality rates were significantly lower for DMC-THA with a risk ratio 0.31 (95% CI, 0.16-0.59;I-2 = 0%,p = 0.0003) and 0.55 (0.40, 0.77;I-2 = 0%,p = 0.003) respectively when compared to biploar hemiathroplasty (BHA). Conclusions: The mean dislocation and mortality rates in DMC-THA are lower than previously reported rates for THA with single cup and comparable to unipolar and bipolar hemiarthroplasty. Further research involving randomised control trials to assess differences in outcomes, longevity and cost-effectiveness needs to be conducted to make recommendations for the use of DMC in treating FNFs.