<prompt> When a patient gets up from sitting position which of the following events takes place in his knee joint?Medial rotation of femur on a fixed tibiaLateral rotation of femur on a fixed tibiaMedial rotation of tibia on a fixed femurLateral rotation of tibia on a fixed femur  <response>: Physiological locking occurs in extension when the femur is internally medially rotated on a fixed tibia.Locking is a mechanism that allows the knee to remain in the position of full extension as in standing without much muscular efforts and is caused by quadriceps femoris. 