Implant Design and Effects on Patellofemoral Crepitus.

Abstract

<b>Background</b> Patellofemoral crepitus is a known complication of posterior stabilized (PS) total knee arthroplasty (TKA). This study compared the incidence of patellofemoral crepitus between two femoral components designs. <b>Materials and Methods</b> Between January 2005 and August 2010, 1,120 patients with complete 2-year follow-up had a PS TKA with two different prosthetic designs (group A, 553 patients; group B, 567 patients). Records were reviewed to identify the incidence of total, symptomatic, and operative patellofemoral crepitus. <b>Results</b> No statistical differences were observed in the incidence of total patellofemoral crepitus (group A 14.1%, group B 14.5%; <i>p</i> = 0.932) or symptomatic patellofemoral crepitus (group A 5.6%, group B 4.2%; <i>p</i> = 0.334). The incidence of operative crepitus was greater in group A (3.3%) than in group B (1.3%; <i>p</i> = 0.026). Analysis of mobile versus fixed bearing designs showed a higher incidence of total patellofemoral crepitus in mobile bearing TKA (16.04 vs. 4.93%; <i>p</i> = 0.006) within group B only. <b>Conclusion</b> Femoral component design with a smoother intercondylar box transition zone resulted in a lower incidence of operative patellofemoral crepitus. No statistical differences were noted regarding the incidence of total and symptomatic patellofemoral crepitus. Mobile bearing TKA exhibited greater total crepitus within group B. <b>Level of Evidence</b> Level III.