Comparison Between the Attune and PFC Sigma in Total Knee Arthroplasty: No Difference in Patellar Clunk and Crepitus or Anterior Knee Pain

Patellar crepitus and clunk (PCC) is a known complication in total knee arthroplasty (TKA) and the cause of dissatisfaction. Patellofemoral articulations have reportedly been optimized in newer TKAs. This study compared the incidence of PCC between a historical and modern TKA design. A single-surgeon retrospective review of primary PFC Sigma (DePuy Synthes, Warsaw, Indiana) or Attune TKA (DePuy Synthes) was performed. A total of 114 PFC Sigma and 103 Attune implants were analyzed at a mean 3.2 years follow-up for overall PCC, painful PCC, anterior knee pain (regardless of crepitus), and PCC necessitating revision. Similar rates of overall PCC (14.6% vs 20.2%, P=.803), painful PCC (8.7% vs 6.1%, P=.605), and anterior knee pain (15.5% vs 9.7%, P=.219) were observed in the Attune and PFC Sigma groups, respectively. No clinically significant differences in range of motion, pain, or Knee Society Scores were found between groups. Subgroup analyses of mobile vs fixed bearing PFC Sigma implants demonstrated higher rates of overall PCC (32.4% vs 15.0%, P=.043), painful PCC (20.6% vs 5.0%, P=.016), anterior knee pain (17.6% vs 1.3%, P=.003), and crepitus requiring revision surgery (17.6% vs 1.3%, P=.003) for mobile bearing PFC Sigma implants. No difference was found in the rates of anterior knee pain or PCC between the PFC Sigma and Attune implants. Subgroup analysis suggests that a mobile bearing PFC Sigma implant results in higher PCC. The authors believe the true incidence of anterior knee pain and PCC is underreported in the literature because many outcome measures do not capture these complications.