Polyethylene wear characteristics in vivo and in a knee stimulator.

Validation of a wear simulator requires that the device produce a similar type and amount of wear and particles of a comparable morphology as occurs clinically. Using techniques previously established to compare polyethylene particles from hip simulators to those from retrieved tissues, particles isolated from six revised posterior stabilized knee replacements were characterized and compared to particles generated from the same knee design worn in a knee simulator. The particles produced in the knee simulator were of comparable size but had less variability in their form factor compared to the particles produced in vivo. Comparable wear features were seen on the articulating surfaces in both groups. These results indicate that this knee joint simulator is able to reproduce a baseline type of wear that is similar to that in vivo and should encourage further use of this device to better understand knee component wear and function.