title: Complete polyethylene wear-through and secondary breakage of the expansion cup in a ceramic-polyethylene total hip.
abstract: BACKGROUND
  Catastrophic polyethylene failure is an uncommon complication of ceramic-on-polyethylene total hip arthroplasty (THA) because of the favourable tribological characteristics of these implants. We present a case of a 50-year-old woman who formerly underwent bilateral ceramic-on-polyethylene THA with expansion acetabular cups and eleven years later presented with unilateral THA dislocation, secondary to catastrophic polyethylene failure and metal shell fracture.
  
  
  METHODS
  The patient came to our hospital for worsening pain in her left hip and an acute incapacity to bear weight on her left lower limb. Twelve and eleven years earlier she had undergone bilateral ceramic-on-polyethylene THA with acetabular expansion components of identical size on both sides. Radiographically, the left femoral head appeared superiorly dislocated and severe polyethylene wear was detected. The inclination angles of the left and right cups were 60° and 44°, respectively. The patient underwent left acetabular revision, and complete polyethylene wear-through with fracture of a cranial lobe of the expansion metal shell was noted at surgery. One large osteolytic lesion in the roof of the acetabulum and diffuse periarticular metallosis were also present. These findings required the use of a Burch–Schneider reinforcement cage. Two years later the patient is functioning well and has full autonomy in her activities of daily living.
  
  
  CONCLUSIONS
  The correct inclination of the acetabular component is necessary to prevent accelerated polyethylene wear in THA, even though favourable articular bearing surfaces have been used (e.g., ceramic-on-polyethylene coupling). Should the cup appear well fixed and fairly oriented on follow-up radiographies, the early detection of severe polyethylene wear may permit a revision of only the femoral head and acetabular liner.
authors.affiliation: Department of Orthopaedic Surgery and Traumatology, University of Naples Federico II School of Medicine, Naples, Italy. maricond@unina.it
authors.forename: Massimo
authors.initials: M
authors.lastname: Mariconda
authors.forename: Alessandro
authors.initials: A
authors.lastname: Silvestro
authors.forename: Gelsomina
authors.initials: G
authors.lastname: Mansueto
authors.forename: Domenico
authors.initials: D
authors.lastname: Marinò
mesh_terms: D019644:Arthroplasty, Replacement, Hip / Q000295:instrumentation*; D002516:Ceramics; D005260:Female; D006622:Hip Prosthesis / Q000009:adverse effects*; D006801:Humans; D008875:Middle Aged; D020959:Polyethylene; D011475:Prosthesis Failure; D012086:Reoperation
chemical_list: D020959:Polyethylene