Patellar clunk syndrome in total knee arthroplasty without patellar resurfacing.

In a series of 647 total knee arthroplasties, the patella was not resurfaced if bony geometry of the patella was good enough to maintain good congruency of the patella undersurface to the femoral component and the patella was tracking normally at the femoral component groove at the time of surgery. Three hundred seventy-two total knee arthroplasties were done with a femoral component that had the same geometry as the original total condylar prosthesis. None of these knees resulted in patellar catching, whether the patella was resurfaced or not. Two hundred seventy-five total knee arthroplasties were done with a more contemporary femoral component with wider intercondylar space and shorter posterior extension of the intercondylar notch. Eleven of these 275 knees demonstrated catching of the patella at 60 degrees to 90 degrees of flexion when the knee was tested from flexion to extension during the surgery. All of these 11 knees did not have patellar resurfacing during surgery at first. Of these 11 knees with patellar catching noted during surgery, at first, patellar catching was eliminated with patellar resurfacing in 4 and by shaving of the superior pole of the patella in 7. None of the knees with the patella resurfacing in this series showed patellar catching.