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 5years. 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.