The main form of training for postoperative bending after comminuted patella fracture surgery is knee flexion training, which usually requires active knee flexion to 90 degrees by one month postoperatively. The specific training method is as follows: The next day after surgery, you can use foot dorsiflexion plantarflexion to carry out isometric contraction functional exercise of quadriceps muscle; straight leg raising training and standing out of bed after 48-72 hours after surgery; 3 weeks after surgery, start knee flexion activities. 1. Patients can first use the strength of the knee to bend the knee, or they can squat slowly by holding the railing to practice knee bending. 2. If the patient is unable to practice slow squatting, he/she can use the tension band to put on the ankle joint, pull the ankle back with the strength of both hands, and bend the knee joint with the help of external force. 3. The patient sits on the edge of the bed and slowly drops down to bend the knee with the help of the strength of the lower leg. Resistance can be increased appropriately to help bend the knee. After the condition of comminuted fracture of the patella is stabilized, it is necessary to start the knee bending exercise as early as possible, and the exercise should be gradual, avoiding violent bending of the knee joint, so as to avoid re-injury. It is recommended that postoperative knee bending training for comminuted patella fracture should be carried out under the guidance of professional physicians or rehabilitation therapists.