Study of 4 Cases of Intraprosthetic Dislocation in the Dual-Mobility Cup

Introduction: The occurrence of intraprosthetic dislocation, a complication specific to the dual-mobility cup, is a concern for practitioners. The objective of this study is to determine whether a varus femoral stem is a risk factor for the occurrence of this type of dislocation.

Patients and Methods: This was a prospective study of 4 cases of intraprosthetic dislocations in total hip arthroplasties with dual-mobility cups, collected over a period of 6 months at the Orthopedic and Traumatology Department of the Metropole Savoie Hospital Center. The patients included were aged 63 years and older, had presented with an intraprosthetic dislocation, and required surgical revision.

Results: The average age of the patients was 74 years. The circumstances surrounding the occurrence of these intraprosthetic dislocations were marked by domestic accidents from falling from their height (50% of cases), followed by ski accidents and falls in the mountains (25% each). Three out of the four femoral stems were varus.

Conclusion: Intraprosthetic dislocation in the dual-mobility cup is becoming an increasingly rare accident, and the varus femoral stem may, among other factors, constitute a contributing factor.

Keywords: Intraprosthetic Dislocation, Dual Mobility, Varus Femoral Stem, Total Hip Arthroplasty.