Abstract
Background: It is still controversial to resurface the patella during total knee arthroplasty (TKA). In this study, we focused on the configuration of the femoral component and the shape of the patella.
Methods: Four different trial femoral components were inserted into a saw-bone of the femur. In each femur, a K wire of 2.0 mm in diameter was inserted through the medial and lateral epicondyles. The saw-bone was attached to a specially designed measuring device so that the femur could be rotated around the K wire. The femur was rotated to express flexion of the knee in 15° increments up to 130° of flexion. A picture of the femoral condyle was taken in each angle of flexion. On each image, the contour of the component was drawn and the configuration of the patellar groove was compared among the systems.
Results: The results showed that the patellar groove of the Zimmer LPS has a wide and deep shape, and the Stryker NRG has the almost the same configuration of the patellar groove with the normal knee. The differences of the patellar groove configuration would induce different clinical results after TKA regardless of the resurfacing of the patella. The shape of the patella is one factor for resurfacing. The patellar groove of Stryker NRG matches the shape of the normal femur. Therefore, the patella with an abnormal shape should be resurfaced even though the cartilage is intact.
Conclusion: Resurfacing of the patella should be decided according to several conditions such as patellar cartilage damage, the shape of the patella and the configuration of the femoral component used in TKA.
