Early Catastrophic Failure of Highly-Cross-Linked Polyethylene Liner Due to Acetabular Shell Screw Placement: A Case Report.

Highly cross-linked polyethylene (HXLPE) has become the standard acetabular liner material in total hip arthroplasty (THA) because it has markedly reduced wear-related osteolysis and aseptic loosening. However, cross-linking also reduces resistance to fatigue and crack propagation, which may lead to failure in areas of concentrated stress. Acetabular liner failure remains rare and most commonly occurs following trauma. We report an atraumatic early catastrophic failure of an HXLPE acetabular liner in a 62-year-old woman, 20 months after primary THA at an outside institution. She presented with groin and lateral hip pain, joint squeaking, and an inability to flex the hip past 90 degrees. Radiographs demonstrated eccentric positioning of the femoral head within the acetabular shell and displacement of the acetabular locking ring. During revision, the liner was found fractured into multiple fragments with surrounding metallosis. An eccentrically placed acetabular shell screw protruded into the inner surface of the shell, and the location of the screw head corresponded with backside liner wear. The rim screw was removed and the liner was exchanged. At telephone follow-up over eight years later, the patient reported ambulating without difficulty and denied pain or subsequent revision. This case describes a preventable, technique-dependent mechanism of early HXLPE liner failure and supports routinely confirming flush seating of the acetabular screw before liner insertion during THA.