[Dislocation of the polyethylene in a patello-femoral replacement with a movable patella].

Patellofemoral arthroplasty is an infrequently used surgical technique because of its controversial results. In an attempt to improve the results, a design with a mobile-bearing poliethylene patellar component has been developed. We describe a clinical case with an unusual complication: the dislocation of poliethylene from the metal backing; and accordingly, we carried out a literature review of this complication.