Traumatic Disassembly of a Bipolar Hip Prosthesis - A Case Report -

We report a rare case of a complete disassembly of the inner head from the bipolar cup without polyethylene wear and locking system failure. An 84-year-old man who had a femur neck fracture of the right hip underwent a replacement of the bipolar prosthesis 4 months ago. He fell down from a height of a chair and felt a sudden sharp pain in the right hip. Roentgenograms revealed that the inner head was dislocated from the outer cup; subsequently, a revision surgery was carried out. When the outer head was removed from the acetabulum, the bearing insert and locking ring were not deformed. Because there was no evidence of loosening of the femoral stem, identicallysized bipolar cup and metal head replacement was performed. At a 6 months follow-up, he had mild hip pain but had returned fully to daily living.