Femoral Implant Design Modification Decreases the Incidence of Patellar Crepitus in Total Knee Arthroplasty

Abstract

BackgroundPatellar crepitus is a complication most commonly seen in patients implanted with a posterior-stabilized total knee arthroplasty (TKA). Recently, design changes in the patellofemoral geometry and the intercondylar box ratio have been optimized in newer TKA designs. A comparative study was performed to analyze the incidence of patellar crepitus between a historical vs modern TKA design. MethodsA retrospective review of all patients at our institution that underwent a primary TKA with either a PFC Sigma or Attune posterior-stabilized TKA (DePuy, Inc, Warsaw, IN), with a minimum of 1-year follow-up duration was performed. A total of 1165 participants implanted with the PFC Sigma and 728 with the Attune design were analyzed. Patellar crepitus incidence, functional scores, and range of motion were recorded at each follow-up appointment. Statistical analyses were performed between the 2 groups to determine if there were differences in clinical outcomes. ResultsThe incidence of crepitus in participants implanted with the Attune was 0.55% vs 6.26% in the PFC Sigma cohort (P < .001) at 1 year vs. 0.83% vs 9.4%, respectively at 2 years post operatively (P < .001). There were small differences in extension, flexion, and Knee Society Scores between the 2 groups that were not clinically meaningful. ConclusionThe Attune posterior-stabilized TKA demonstrated substantially less patellofemoral crepitus incidence than the historical control. We hypothesize that these findings are related to femoral component changes including a thinner and narrower anterior flange and a reduced femoral intercondylar box ratio.