In case of knee effusion, the first step is to reduce the effusion through medication and physical therapy, followed by exercises, mainly squatting exercises, straight leg raising exercises and quadriceps isometric contraction exercises. The common causes of knee effusion are joint injury and synovitis, which are first treated with anti-inflammation and swelling reduction through medications such as ibuprofen and diclofenac, as well as physical therapy such as ultrashort wave and laser. When the inflammatory response is reduced, there is often a decrease in muscle strength around the knee joint, which can be improved through training. 1. Static squatting exercise: take an upright position, feet shoulder-width apart, straighten your hands and then squat, keep flexing at 90 degrees, keep it for five to ten minutes, and repeat several times. 2. Straight leg raising exercises: take the supine position, straighten the legs, and then raise the legs upward about 30 degrees, keep about ten seconds, practice a few times a day, to help maintain the stability of the knee. 3. Quadriceps isometric contraction exercise: lie on your back on the bed, straighten both lower limbs, and then force the quadriceps to contract, driving the patella to move up and down, through this exercise, you can exercise the quadriceps strength. It is recommended that patients seek medical treatment in time, under the guidance of the doctor or rehabilitation therapist to carry out rehabilitation exercises.