Acute Intraprosthetic Dissociation of a Dual-Mobility Hip in the United States.

After decades of use in Europe, dual-mobility (DM) components for total hip arthroplasty (THA) were approved by the US Food and Drug Administration (FDA) in 2011 for use in the United States. DM-THAs are designed with an inner articulation between the femoral head and a larger polyethylene insert, and an outer articulation between the mobile polyethylene and a highly polished metal insert, to increase motion and minimize impingement. Intraprosthetic dissociation (IPD), defined as separation of the femoral head from the inner polyethylene articulation, is usually caused by polyethylene wear, and occurs 3 to 10 years after implantation. Early recognition of this complication is important for appropriate treatment. Late chronic IPD is caused by polyethylene wear, blocked motion of the outer bearing, or acetabular loosening. Acute IPD (AIPD), which occurs within 1 year after implantation, is rare and poorly understood. Only 2 cases of this early complication have been reported in the United States. The exact mechanism of injury is unknown, but AIPD may be associated with closed reduction maneuvers or neck impingement (large-diameter femoral neck, femoral head with skirted neck). In this article, we report the case of a nondemented 63-year-old man who developed AIPD 3 months after implantation of a DM component for recurrent dislocation.