Knee stiffness is divided into two methods of exercise, one is passive activity, the other is active activity exercise, as follows: 1, passive activity: take hip flexion, knee flexion exercise knee function with the help of a doctor, the doctor grasps one calf with one hand, the other hand grasps the thigh, then knee flexion, knee flexion exercise, also passive activity. If there is no doctor, the CPM machine in the ward can be used, and the machine can be put to carry out passive activities of hip flexion and knee flexion, and functional exercises can be carried out with the assistance of the machine to improve knee stiffness. 2. Active activities: For patients whose functional stiffness is not particularly obvious, they can rehabilitate themselves at home, that is, active activities, and hip flexion and knee flexion exercises can be given after prone position. Sitting position is also possible, the calf can be straightened and the patient can sit on a chair for knee flexion exercises. If the exercises are not particularly effective, physical therapy can only be requested from a rehabilitator.