Dissociation of mobile-bearing patellar component in low contact stress patellofemoral arthroplasty, its mechanism and management: two case reports.
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.
van Jonbergen
Hans-Peter W
HP
Department of Orthopaedic Surgery, Deventer Hospital Nico Bolkesteinlaan 75, 7416 SE Deventer The Netherlands. vanjonbergen@dz.nl
Werkman
Dirk M
DM
Barnaart
Alexander Fw
AF