Patellar component size effects patellar tilt in total knee arthroplasty with patellar resurfacing

PURPOSE: Patellar component positioning and patellofemoral kinematics are of great importance in total knee arthroplasty (TKA). The factors influencing patellar tilt are femoral rotation and lateral patellar release. However, the effect of patellar component size remains unknown. The aim of this study was to evaluate the intra-operative risk factors for patellar tilt, particularly the effect of the patellar component size. The hypothesis was that increasing the patellar component size would reduce the risk of patellar tilt. METHODS: 878 primary TKAs with patellar resurfacing were included between January 2015 and October 2018.Analysis was performed at 1-year postoperatively on patients categorized into two groups: patellar tilt (PT) and no patellar tilt (NPT). A multivariate analysis was performed for the effect of patellar component size, femoral rotation, femoral overbuilding, patellar thickness and lateral release on patellar tilt risk. Secondary analysis was performed for any difference in clinical outcomes and revision rates between groups. RESULTS: Multivariate analysis showed that increasing the patellar component size decreased the risk of patellar tilt by 37% (