In open-chain knee extension (tibia on femur), what happens at the tibiofemoral joint?

• A. Tibia rolls and slides anteriorly
• B. Tibia rolls and slides posteriorly
• C. Tibia slides in place without rolling
• D. Only the menisci move

Answer: (A)

Open-chain knee extension involves the tibiofemoral surfaces moving together as the tibia slides on the femur. The tibial plateau is concave while the femoral condyles are convex, so the contact point moves by rolling and gliding in the same direction. As the knee extends, the tibia rolls anteriorly and glides anteriorly across the femoral condyles. This anterior roll-glide pattern is opposite to what you’d see during flexion, where the tibia would roll and glide posteriorly. The idea that the joint only slides in place or that only the menisci move isn’t accurate—the tibiofemoral surfaces themselves are moving with a coordinated roll and glide.