Severe polyethylene wear in uncemented acetabular cup system components - A report of 5 cases

We report 5 cases of severe failure of the polyethylene liner at 4 to 7.4 y ears after uncemented anatomic medullary locking (AML) total hip arthroplas ty, using the acetabular cup system (ACS). The mode of failure was by a com bination of wear-through to the metal backing and liner fracture. Four of t he 5 cases were associated with a 32-mm head. The ACS design is flawed beca use of a lack of hemispherical geometry resulting in rim loading on a regio n of the liner that has the thinnest polyethylene. All patients with this t ype of implant should be monitored for evidence of excessive polyethylene w ear.