Condylar-stabilizing tibial inserts do not restore anteroposterior stability after total knee arthroplasty

The Triathlon condylar-stabilizing (CS) lipped insert is designed to provide anteroposterior (AP) stability of the posterior-stabilized (PS) insert, without a post. The purpose of this study was to compare the AP stability of the knee in patients with Triathlon CS and PS total knee arthroplasty (TKA) with midterm follow-up. Thirty-one patients received a Triathlon PS TKA in one knee and a Triathlon CS TKA in the contralateral knee, and 28 patients were followed up with a minimum duration of 5. years. Although there was no difference in functional outcomes, the posterior displacement was significantly greater in the CS TKA group than in the PS TKA group (P < 0.001). The Triathlon CS lipped insert could not restore posterior stability with PCL sacrifice.