Anatomy General 7246836b Locking of knee joint occurs due to - A Lateral rotation of femur during last degrees of extension. B Medial rotation of femur during last degrees of extension C Lateral rotation of femur during last degrees of flexion D Medial rotation of femur during last degrees of flexion High-Yield Explanation During last stages of extension, femur rotates medially on tibia due to quadriceps femoris to lock the knee joint.