For a small amount of fluid in the knee joint, it usually takes 2-4 weeks to be absorbed. The synovial membrane of the knee joint secretes joint fluid and also resorbs joint fluid so that it completes its circulation and metabolism within the joint. When inflammation of the synovial membrane occurs, the synovial membrane’s ability to reabsorb is reduced, resulting in increased secretion and fluid accumulation in the joint. Therefore, in order to promote rapid absorption of joint fluid, treatment should be directed at synovitis. Treatment includes resting the knee joint, reducing weight bearing and activity, local heat application or microwave therapy, and oral non-steroidal anti-inflammatory drugs such as celecoxib, as well as muscle exercises around the knee joint, such as static contraction of the quadriceps. With these comprehensive treatments, the knee joint fluid can be rapidly absorbed within 2-4 weeks. It is recommended to protect the knee from cold and humidity, not to walk with weight, and to avoid heavy physical work and strenuous activities. Elevate the affected limb and rest properly.