After the cast is removed, you should gradually transition from passive to active knee flexion with the help of a rehabilitation physician and physical therapy. After removing the cast, long-term braking will cause muscle adhesion, which will lead to stiffness of the joint and inability to bend the knee. You should go to the rehabilitation department for rehabilitation treatment in time. Firstly, you should gradually open the mobility of the knee joint with the assistance of the rehabilitator and carry out passive movement, and you can carry out straight leg raising training at the bedside. Afterwards, you can gradually use towels, tension ropes and other external forces to help move the knee joint, stand against the wall, and gradually bend the knee until the transition to actively complete the action of bending the knee. It should be noted that when opening the knee joint mobility should be within the tolerance range to avoid secondary injuries. In addition to joint mobility training, you should also gradually enhance the strength of the surrounding joint muscles to help stabilize the knee joint, but also with massage, infrared therapy. How to practice knee flexion after removing the plaster, specifically can consult the professional doctor’s opinion, under the guidance of the doctor to carry out rehabilitation exercises, in order to prevent the improper exercise caused by the body injury.