During open-chain knee extension, which statement correctly describes tibial movement relative to the femur?

During open-chain knee extension, which statement correctly describes tibial movement relative to the femur?

• A. The tibia rolls and slides anteriorly during open-chain extension
• B. The tibia rolls posteriorly and slides anteriorly
• C. The patella tilts during knee flexion
• D. The tibia remains stationary during extension

Answer: (A)

In open-chain knee extension, the lower leg (tibia) moves on a relatively fixed femur. The tibial plateau is concave while the femoral condyles are convex, so when a concave surface moves on a convex surface, roll and glide occur in the same direction. As the knee extends from flexion, the tibia rolls anteriorly and glides anteriorly relative to the femur, producing anterior tibial translation. That’s why extending the knee involves the tibia moving forward on the femur. The other ideas don’t fit: posterior rolling would occur with flexion, the tibia does move (it isn’t stationary), and patellar tilting relates to the patellofemoral joint during flexion, not the tibiofemoral movement described here.

In open-chain knee extension, the lower leg (tibia) moves on a relatively fixed femur. The tibial plateau is concave while the femoral condyles are convex, so when a concave surface moves on a convex surface, roll and glide occur in the same direction. As the knee extends from flexion, the tibia rolls anteriorly and glides anteriorly relative to the femur, producing anterior tibial translation.

That’s why extending the knee involves the tibia moving forward on the femur. The other ideas don’t fit: posterior rolling would occur with flexion, the tibia does move (it isn’t stationary), and patellar tilting relates to the patellofemoral joint during flexion, not the tibiofemoral movement described here.