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Knee flexion means bending your leg at the knee joint, reducing the angle between your lower leg and upper leg.
As the knee is a synovial hinge joint, its function is to permit the flexion and extension of the lower leg relative to the thigh. The range of motion of the knee is limited by the anatomy of the bones and ligaments, but allows around 120 degrees of flexion.A special characteristic of the knee that differentiates it from other hinge joints is that it allows a small degree of medial and lateral rotation when it is moderately flexed.n the anterior surface of the knee, the patella is held in place by the patellar ligament, which extends from the inferior border of the patella to the tibial tuberosity of the tibia. Posteriorly, the oblique popliteal ligament and arcuate popliteal ligament join the femur to the tibia and fibula of the lower leg.