Penetration of a metallic femoral head through the acetabular shell

Extensive wear of a metal-on-polyethylene total hip arthroplasty may rarely result in erosion of the metal-backed acetabular shell and penetration of the femoral head. We report on the case of an 85-year-old man who presented to the emergency department with an apparent dislocated total hip. He subsequently was discovered to have a periprosthetic fracture after an attempt at closed reduction of what was only discovered intraoperatively to be an irreducible transacetabular component central dislocation. Recognition of this rare complication may change clinical outcome.