Dislocation of the polyethylene liner in hip arthroplasty: 6 patients with dislocation within 3 years.

We revised 6 patients with early destruction of the liner in a cementless press-fit acetabular cup. They had no signs of infection or evidence of trauma. The failures were probably due to rotation of the liner inside the metal shell and destruction of the polyethylene by the cutting edge of the metal. This early complication may be difficult to diagnose because of normal radiographs. We suggest that the manufacturer should provide the insert with a metal marker to make this complication easier to detect.