The squat is one of the most convenient and effective ways to exercise quadriceps strength, and after knee surgery, proper practice of the squat can greatly accelerate the progress of recovery. The method and precautions for squatting are as follows: lean back against the wall, legs apart, feet shoulder-width apart, body remains upright, not leaning forward, at this time both knees begin to bend squatting, the long axis of the lower leg as vertical as possible with the ground. Both knees bend at different angles according to the patient’s physical condition and muscle strength. Generally the first practitioners quadriceps strength is weak, you can start practicing from 30 degrees of flexion, later as the exercise proceeds, muscle strength increases, and then increase the angle of knee flexion (the maximum can be up to 90 degrees, but do not exceed, otherwise damage to the knee joint is large). The duration of the static squat varies greatly from person to person, and is generally squatted until it cannot be held. Rest for about 2 minutes between squats, then repeat. Arrange the exercise program according to tolerance, for example, 20 minutes per exercise is considered a group (continuous squat + 2 minutes rest), repeated 3-4 times a day. Squats can be divided into different angles for better exercise of the quadriceps. The recommended angles are 30, 60, and 90 degrees. All exercise methods should not cause severe pain, otherwise it is often harmful, and the same applies to the squat. Squatting should be done at an angle that does not cause significant pain. Sometimes, practitioners have a painful angle when squatting, some squatting to 30 degrees pain, some squatting to 40 degrees or 60 degrees pain, practice to avoid their specific pain angle, for example, if squatting to 30 degrees pain, you can continue to squat down to 45 degrees, and so on.