Fig. 1.

a The Logic PS implant shows a reduction in metal on either side of the trochlear groove, which allows for less retinacular tension (arrows). In addition, the bony overhang is anteriorly reduced by the left and right specific femoral component and the use of half sizes. b The Optetrak PS implant has noticeably more metal on either side of the trochlear groove (arrows) and is less smooth than the Logic PS. In addition, the bony overhang is greater due to the lack of femoral-specific components.