title: Dissociation of mobile-bearing patellar component in low contact stress patellofemoral arthroplasty, its mechanism and management: two case reports.
abstract: BACKGROUND
  Isolated patellofemoral osteoarthritis can be treated with patellofemoral arthroplasty.
  
  
  METHODS
  We present two cases of isolated patellofemoral osteoarthritis treated with Low Contact Stress patellofemoral arthroplasty; in both cases the polyethylene mobile-bearing of the patellar component dissociated from the metal backing. One patient had a revision to a Richards patellofemoral prosthesis, and in the second patient the arthroplasty was converted to a total knee prosthesis because of clinically important femorotibial osteoarthritis.
  
  
  CONCLUSIONS
  The possible failure mechanisms are described. We suggest avoiding the use of a metal-backed mobile-bearing patellar component due to the risk of dissociation.
authors.affiliation: Department of Orthopaedic Surgery, Deventer Hospital Nico Bolkesteinlaan 75, 7416 SE Deventer The Netherlands. vanjonbergen@dz.nl
authors.forename: Hans-Peter W
authors.initials: HP
authors.lastname: van Jonbergen
authors.forename: Dirk M
authors.initials: DM
authors.lastname: Werkman
authors.forename: Alexander Fw
authors.initials: AF
authors.lastname: Barnaart