[Dislocation-dissociation of a bipolar hip prosthesis].

The incidence of hip prosthesis dislocation ranges from 0.4% to 15% depending on the series (1, 6). In classical dislocations of hip prosthesis, the prosthetic femoral head escapes from the natural acetabular cavity or prosthetic acetabulum in case of total hip arthroplasty. In the case presented here, a bipolar hip prosthesis dislocation occurred between the small head of the prosthesis and the polyethylene. A total hip prosthesis restored good function. Only a few cases of this type have been described in the literature. The different causes are discussed.