John A. Anderson, MD, MRCS; Andrea Baldini, MD; Thomas P. Sculco, MD J Knee Surg. 2008; 21:91 ABSTRACT Knee complications and function were analyzed in patients with 2 different posterior-stabilized total knee arthroplasty (TKA) designs, Optetrak 913 and Insall-Burstein II. Three hundred Insall-Burstein II knees with mean follow-up of 8 years (range: 5-9 years) and 300 Optetrak knees with mean follow-up of 6 years (range: 5-7 years) were studied. Lateral retinacular release was performed in 30% of Insall-Burstein II patients and 16% of Optetrak patients (P=0.001), and patellar clunk was 4% for the Insall-Burstein II prosthesis and 0.3% for the Optetrak prosthesis (P=0.003). No statistically significant differences in dislocation, fracture, or loosening rates were observed between the 2 groups. Knee Society scores were similar in 2 groups of 50 patients brought back to the office. Mean Knee Society knee scores were 92 and 94 for the Insall-Burstein II and Optetrak groups, respectively (P>0.05), and function scores were 80 and 84 for the 2 groups, respectively (P>0.05). At midterm follow-up, Optetrak patients were less likely than Insall-Burstein II patients to require lateral retinacular release and experience patellar clunk.