Radiostereometric measurement of polyethylene deformation pattern in meniscal bearing TKR at 5 years follow-up.

To determine polyethylene deformation in well-functioning meniscal bearing PCL-retaining total knee prosthesis a quantitative stereophotogrammetric analysis was carried out over 5 years' follow-up. Polyethylene plastic deformation was obtained by tracking the intermarker distance variations of five tantalum beads inserted into the polyethylene prior to surgery in a known position. Plastic deformation occurred in the posteromedial part of the meniscal bearing. Radiostereometric analysis was a useful tool to monitor the load distribution in vivo on the polyethylene of this meniscal bearing prosthesis. This analysis revealed a very similar pattern of plastic deformation in the polyethylene insert of this prosthesis design to the wear pattern revealed with different methodologies in PCL-retaining fixed-bearing prosthesis.