Intraprosthetic Dislocation Following Dual-Mobility Total Hip Arthroplasty: A Case Report

Dual-mobility total hip arthroplasty has been increasingly adopted to improve joint stability and reduce postoperative dislocation. Despite these advantages, this implant design is associated with specific modes of failure. One such complication is intraprosthetic dislocation, which occurs when the femoral head disengages from the polyethylene liner. Although uncommon, this condition is clinically important and may not be readily identified at initial presentation. We report a case involving a 67-year-old woman who presented with sudden onset of hip pain and mechanical restriction of movement two years after undergoing dual-mobility total hip arthroplasty for a fracture neck of femur. Radiographic assessment revealed abnormal positioning of the femoral head within the acetabular component, suggesting dissociation of the polyethylene liner. Computed tomography further supported this diagnosis, and inflammatory markers were within normal limits. Surgical exploration confirmed intraprosthetic dislocation of the liner, while both the femoral stem and acetabular shell were well fixed. Management consisted of removing the mobile bearing and converting the articulation to a fixed polyethylene liner within the existing acetabular cup. Postoperatively, the patient recovered without complications and demonstrated sustained functional improvement without recurrent instability at one year. This case underscores that intraprosthetic dislocation remains a potential cause of mechanical failure even with contemporary dual-mobility implants. Because clinical symptoms may be subtle, careful attention to characteristic imaging findings is essential to avoid diagnostic delay. When implant fixation is preserved, selective exchange of modular components can provide a successful and less invasive treatment option. Prompt recognition and appropriate surgical intervention are crucial to prevent further prosthetic damage and to achieve satisfactory functional outcomes.