1.Training to enhance muscle strength Mainly applicable to the stage when the knee joint cannot move with a large range of motion and the braking stage. Prevent muscle atrophy and promote muscle strength recovery. 1) Lie on your back with the healthy leg flexed, the affected knee extended, the ankle dorsally extended, while the N fossa forcefully presses down on the bed, consciously contracting the quadriceps muscle to pull the patella toward the centripetal end, and then relaxing. The main purpose is to enhance the muscle strength of the quadriceps. 2) Lie on your back, bend the knee of the healthy leg, extend the affected knee, dorsal extension of the ankle, contract the posterior femoral muscles to press the heel to the bed, gradually increase the force, and then relax. The main purpose is to enhance the muscle strength of the femoral flexors. 3) Supine or sitting position, both knees straight, a soft pillow is placed between the two knees, both knees contract the medial femoral muscles at the same time, and gradually squeeze the soft pillow with force, then relax. 4) straight leg raise exercise sitting or supine position, the healthy leg flexion, the affected limb joint extension, ankle dorsal extension, for straight leg raise, the height of about heel from the bed about 15CM, adhere to 5-9 wonderful, slowly put down. 2, maintenance of joint mobility training 1) foot along the wall slide training method: the patient’s head to the direction of the end of the bed, supine on the bed, body and bed vertical, flexion of the hip about 90 °, the affected foot stirrup on the wall, the use of limb gravity, the affected foot slowly slide down until the affected knee has a sense of tension, so repeatedly, 5-10 times each time, twice a day. 2) Bedside knee flexion training method: The patient sits on the edge of the bed with both lower limbs naturally hanging down and the upper body upright, holding the edge of the bed with both hands. The affected foot is flexed and the affected knee is slowly flexed until the affected knee feels taut, then the knee is gradually straightened while the affected toe is dorsally extended. 3) Supine two-handed knee training method: supine position, the healthy limb knee extension, the affected limb hip flexion and knee flexion, the patient’s hands around the affected knee, the affected foot Tsuge flexion, knee joint gradually flexion. Then gradually extend. 3.Passive activities There are two main types of passive activities, one is the passive activities of the joint with the help of the rehabilitation physiotherapist. The other is the joint mobility training by the patient himself using his own gravity. This section introduces the passive training using the patient’s own gravity and equipment. 1) Foot slide along the wall training method: the patient’s head towards the end of the bed, lying supine on the bed, the body is perpendicular to the bed, flexion of the hip about 90 °, the affected foot on the wall, the healthy ankle behind the affected ankle on top, using the gravity of the limb and the force of the healthy side of the limb, so that the affected foot slowly slide until the affected knee has a sense of tension, so repeated. Purpose: To increase knee flexion. 2) Bedside knee flexion training method: The patient sits on the bedside with both lower limbs naturally hanging down and the upper body upright, holding the edge of the bed with both hands. The back of the ankle on the healthy side is placed in front of the ankle on the affected side and slowly flexed until the affected knee feels taut. Purpose: To increase the flexion of the knee joint. 3) Prone position training method: lie prone, try to flex the affected knee, place the healthy ankle cross in front of the affected ankle and use the strength of the healthy limb to slowly pull the affected knee to flex gradually near the hip. Objective: To increase the flexion of the knee joint. 4) Supine training method: Lie on your back, try your best to flex the affected knee, cross the ankle on the healthy side in front of the affected ankle, and use the strength of the healthy limb to slowly pull the affected knee to flex gradually closer to the hip. Purpose: To increase the flexion of the knee joint. 5) Prone extension training: Lie prone with the front of the healthy ankle crossed over the back of the diseased ankle and gently push the diseased knee straight until the affected knee feels a sense of tension. Purpose: To increase the extension of the knee joint. 6) Passive exercise with the help of apparatus (CPM): CPM machine is an effective passive exercise method to prevent the limitation of joint movement and promote the regeneration and repair of articular cartilage.