Abstract
BACKGROUND: With the increase in life expectancy and the rising number of total hip arthroplasty (THA) cases, the rate of complications is also expected to increase. One of the most challenging complications is dislocation, which is the leading cause of revision surgery within the first year after THA. This study aimed to assess hip instability rates in high-risk patients who underwent dual mobility cup (DMC) implantation. METHODS: This retrospective study reviewed all patients who underwent THA with DMC at Rasul-e-Akram Hospital between 2014 and 2021. DMC was used in high-risk patients for dislocation, including those with neuromuscular diseases (e.g., Parkinson's disease, poliomyelitis) and intracapsular femoral neck fractures (FNF), instead of the standard cup. Clinical outcomes, instability, and other complications were recorded. All data was analyzed using SPSS software version 27.0.1. The chi-squared test was used to compare binary variables, and the student's t-test was used to compare numerical variables after checking for normal distribution. RESULTS: A total of 163 patients (168 hips) underwent THA with DMC, with a mean age of 58 ± 5.3 years. Five patients had bilateral total hip surgery. The average follow-up time was 48 ± 5.8 months. The average BMI of patients was 28.3 ± 3.1. The preoperative Harris Hip Score (HHS) was 49 ± 8.5, while the postoperative HHS at the four-year follow-up was 89 ± 2.4. None of the patients experienced a dislocation requiring revision, and One case of severe wear on the polyethylene's inner surface and intraprosthetic dislocation, without a dislocated metal head, was identified and revised. No cases of component loosening or significant osteolysis were observed. CONCLUSION: The use of DMC can significantly reduce the dislocation rate in patients with risk factors such as femoral neck fractures while improving patient satisfaction and restoring near-normal function. We recommend greater consideration of this cup in patients at risk of dislocation.