[Dynamic in vitro measurement of retropatellar pressure after knee arthroplasty]

The purpose of this study was to examine the contact pressure between the patellofemoral interface of the physiologic, native, and prosthetic patella and the femoral component in total knee arthroplasty. An electronic sensor was used to measure contact pressure in five cadaver knees. The average peak contact pressure measured on the prosthetic patella was 9.8 MPa and was significantly higher than the physiologic and native patella. Average peak contact pressures increased with flexion. Although contact pressure reflects only a part of the dynamics of the patellofemoral articulation, these data support the selective retention of the native patella in total knee arthroplasty. Nevertheless, besides the indication for prosthetic replacement of the patella, design and operative techniques should also be part of the discussion.